The overall aim of this thesis is to determine if the interactions between normal and waxy rice starch and milk proteins from four milk protein ingredients, namely skim milk powder (SMP), milk protein concentrate (MPC), sodium caseinate (NaCAS) and whey protein isolate (WPI) do occur, and to identify the mechanisms underlying these interactions. Different milk protein ingredients at various concentrations (0 to 10%, w/w) affected markedly and differently the pasting behaviour of 10% (w/w) rice starches. SMP delayed the pasting of both rice starches by increasing the onset temperature (Tonset) and the peak viscosity temperature (Tpeak) of pasting. This was mainly due to the presence of lactose and ions, which was further supported by the investigation of the effects of UFSMP (a solution of salts and lactose present in SMP at their proper concentration) and lactose. The addition of NaCAS also delayed the pasting of rice starch; Tpeak in the case of both starches was increased. For normal rice starch paste, MPC and WPI decreased the Tpeak. MPC had no affect on Tpeak of waxy rice starch paste. The qualitative viscoelastic behaviour of rice starch/milk protein ingredient gels obtained from the above pastes was dominated by the continuous phase made of the starch molecules. There was evidence, as indicated by confocal microscopy, of phase separation between the milk proteins of SMP and MPC and the two starches. The phase separation was not observed in the addition of either NaCAS or WPI. Studies on the thermal behaviour of rice starch/milk protein ingredient mixtures by differential scanning calorimetry (DSC) showed that SMP, similarly to UFSMP, delayed the gelatinization of both starches. NaCAS also delayed the gelatinisation of both starches but had a greater effect on waxy than normal rice starch. The addition of NaCAS did not affect Tonset but increased Tpeak for normal rice starch, whereas the gelatinisation temperature of waxy rice starch was highly affected by the addition of NaCAS with both Tonset and Tpeak shifted to higher temperatures. MPC had no affect on the gelatinization temperature of normal rice starch, whereas the gelatinization temperature of waxy rice starch was increased by the addition of MPC. The addition of WPI to both rice starches showed two thermal transitions. The first of these was due to the gelatinisation of the starches and the second to the denaturation of ß-lactoglobulin (ß-lg). The addition of WPI to normal rice starch showed that the thermal behaviour of normal starch and protein were independent from each other. In contrast, the thermal behaviour of waxy rice starch was modified by the addition of WPI; both Tonset and Tpeak were increased. SMP decreased the Tonset of swelling, swelling ratio and the amount of starch leaching from both starches. These observed changes were due to the presence of lactose and ions in SMP. NaCAS slightly increased Tonset of swelling but the amount of starch leaching was reduced for both rice starches. The rigidity of both starches tended to increase in the presence of NaCAS. MPC and WPI affected the swelling behaviour of normal and waxy rice starch differently. A dramatic increase in the swelling of normal rice starch/MPC or WPI mixtures was observed, whereas this trend was not evident for waxy rice starch/ MPC or WPI mixtures. The difference in the water holding ability and gelatinization peak temperatures of the two starches over the temperature range at which whey proteins denature and form gels are believed to be responsible for the observed differences. The results from confocal microscopy showed that milk proteins, such as a-casein, ß- casein, ß-lg and a-lactalbumin (a-la), were adsorbed onto the granule surface of both normal and waxy rice starch. The mechanism for this adsorption is the hydrophilic interactions; hydrogen bonds between hydroxyl group from terminated glucan molecule that protrude around starch granule surface-hydroxyl; amino, or other electron-donation or electron-accepting groups of the added proteins. Using sodium dodecyl sulfatepolyacrylamide gel electrophoresis (SDS-PAGE) it was found that for SMP and MPC the adsorbed as- to ß-casein ratio on both starches was similar to the as-casein to ß- casein ratio in the casein micelle at low SMP and MPC concentrations. But at high concentrations of SMP or MPC, this ratio decreased indicating that more ß-casein was adsorbed preferentially to as-casein. In the case of NaCAS, as-casein was adsorbed preferentially to ß-casein. Moreover, there was evidence of multilayer adsorption of ascasein into the surface of rice starch granules. Compared to the other milk protein ingredients, very small amounts of the ß-lg and a-la from WPI were adsorbed onto starch granules. However, the adsorbed amounts of ß-lg and a-la from WPI continuously increased with increasing WPI concentration, suggesting that these two proteins, particularly ß-lg, adsorbed in multilayers too.

Heating milk to high temperatures such as 140 ºC, as used in ultra high temperature (UHT) processing, causes physical and chemical changes in the milk. The production of a cooked flavour is a major change which reduces consumer acceptance of the UHT milk. It has been correlated with the formation of volatile sulphur compounds (VSCs) that result from milk proteins, principally the whey proteins β-lactoglobulin, containing the the sulphur amino acids cystine, cysteine and methionine. The VSCs in milk, whose concentrations are in the parts per billion to parts per million range, are highly reactive, easily oxidised, and sensitive to heat during thermal processing and analysis; this makes them a challenge to analyse. A sensitive method based on gas chromatography with pulsed flame photometric detection coupled with headspace sampling by solid phase microextraction (SPME/GC/PFPD) was developed to detect these compounds in commercial UHT milk and to investigate their production and disappearance during heating and storage. The SPME/GC/PFPD procedure was optimised using different extraction time (15 min, 30 min, & 60 min) – temperature (30 oC, 45 oC & 60 oC) combinations with CAR/PDMS fibre to obtain maximum sensitivity. A short extraction time (15 min) at low temperature (30 oC) was chosen to provide high sensitivity for detecting all VSCs in UHT milk without introducing artefactual VSCs. The extraction method and GC run time (16 min) make this method simple and fast. Nine VSCs were detected in commercial indirectly processed UHT milk, skim and whole. These are hydrogen sulphide (H2S), carbonyl sulphide (COS), methanethiol (MeSH), dimethyl sulphide (DMS), carbon disulphide (CS2), dimethyl disulphide (DMDS), dimethyl sulphoxide (DMSO), dimethyl sulphone (Me2SO2) and dimethyl trisulphide (DMTS). An additional unknown compound was detected but could not be identified by GC/MS because its concentration was below the detection limit of the MS detector. The concentrations of H2S, DMS and DMTS were higher than their threshold values indicating their importance in milk flavour, especially cooked flavour. Several attempts have been made to reduce the cooked flavour in UHT milk. In the current research, the use of hydrogen peroxide (H2O2) to oxidise the VSCs and thereby reduce cooked flavour was investigated. H2O2 is used as a milk preservative and is generally recognised as safe (GRAS) in USA. Several concentrations of H2O2 (0.001%, 0.005%, 0.01%, 0.02% & 0.03%) were added to milk to assess its effects on VSCs and on whey proteins denaturation in UHT milk. H2O2 effectively reduced the concentration of all VSCs, except DMDS which was increased, presumably by oxidation of MeSH. H2S was completely oxidised or reduced below its threshold value. Low concentrations of H2O2 (0.001% & 0.005%) had no effect on, or decreased, the extent of denaturation of β-lactoglobulin when added after or before processing, respectively. Some UHT plants use severe heating conditions, leading to high levels of denaturation of whey proteins, particularly β-Lg, the main source of the VSCs in milk. Correlations between heat severity, β-Lg denaturation and individual VSC generation were investigated in milk batch-heated at 80 oC and 90 oC, and UHT milk processed at 120-150 oC. In accordance with previous reports, β-Lg was more heat-sensitive than α-La. Only five VSCs were detected. The concentrations of H2S and MeSH correlated well with denaturation of β-Lg and α-La. DMS concentration correlated well with β-Lg in UHT milk but not in the batch-heated milk. CS2 did not show a good correlation with heat intensity and appeared to plateau out after a certain level of heating. Conversely, COS and MeSH seemed to require a certain minimum amount of heat before generation commenced; this corresponded to denaturation of β-Lg above 49% and 89% respectively at 80 oC. The higher concentrations of DMS and H2S in UHT milk compared with batch-heated samples having similar degrees of denaturation suggested other possible sources for their production and the importance of the heat severity in generating them. For example, at high heat intensity, S-methylmethionine and thiamine could be sources of DMS and H2S respectively. Furthermore, in whole milk as used in this work, milk fat globule membrane proteins are another source of VSCs. The outcome of this study will help UHT manufacturers to understand the production and disappearance of the VSCs in commercial UHT milk and how to adjust the processing conditions to avoid generation of cooked flavour. Additionally, the promising results of using low concentrations of H2O2 to oxidise the VSCs will provide the industry with another means of reducing cooked flavour. Before H2O2 use is implemented in UHT processing, future studies are required to evaluate all of its effects, including sporicidal effects. Overall, this study makes a contribution to finding a solution to the cooked flavour problem in UHT milk, thereby increasing market share of this milk in countries such as Australia, the UK and North America where cooked flavour is the main barrier to its consumer acceptance.

The overall aim of this thesis is to determine if the interactions between normal and waxy rice starch and milk proteins from four milk protein ingredients, namely skim milk powder (SMP), milk protein concentrate (MPC), sodium caseinate (NaCAS) and whey protein isolate (WPI) do occur, and to identify the mechanisms underlying these interactions. Different milk protein ingredients at various concentrations (0 to 10%, w/w) affected markedly and differently the pasting behaviour of 10% (w/w) rice starches. SMP delayed the pasting of both rice starches by increasing the onset temperature (Tonset) and the peak viscosity temperature (Tpeak) of pasting. This was mainly due to the presence of lactose and ions, which was further supported by the investigation of the effects of UFSMP (a solution of salts and lactose present in SMP at their proper concentration) and lactose. The addition of NaCAS also delayed the pasting of rice starch; Tpeak in the case of both starches was increased. For normal rice starch paste, MPC and WPI decreased the Tpeak. MPC had no affect on Tpeak of waxy rice starch paste. The qualitative viscoelastic behaviour of rice starch/milk protein ingredient gels obtained from the above pastes was dominated by the continuous phase made of the starch molecules. There was evidence, as indicated by confocal microscopy, of phase separation between the milk proteins of SMP and MPC and the two starches. The phase separation was not observed in the addition of either NaCAS or WPI. Studies on the thermal behaviour of rice starch/milk protein ingredient mixtures by differential scanning calorimetry (DSC) showed that SMP, similarly to UFSMP, delayed the gelatinization of both starches. NaCAS also delayed the gelatinisation of both starches but had a greater effect on waxy than normal rice starch. The addition of NaCAS did not affect Tonset but increased Tpeak for normal rice starch, whereas the gelatinisation temperature of waxy rice starch was highly affected by the addition of NaCAS with both Tonset and Tpeak shifted to higher temperatures. MPC had no affect on the gelatinization temperature of normal rice starch, whereas the gelatinization temperature of waxy rice starch was increased by the addition of MPC. The addition of WPI to both rice starches showed two thermal transitions. The first of these was due to the gelatinisation of the starches and the second to the denaturation of ß-lactoglobulin (ß-lg). The addition of WPI to normal rice starch showed that the thermal behaviour of normal starch and protein were independent from each other. In contrast, the thermal behaviour of waxy rice starch was modified by the addition of WPI; both Tonset and Tpeak were increased. SMP decreased the Tonset of swelling, swelling ratio and the amount of starch leaching from both starches. These observed changes were due to the presence of lactose and ions in SMP. NaCAS slightly increased Tonset of swelling but the amount of starch leaching was reduced for both rice starches. The rigidity of both starches tended to increase in the presence of NaCAS. MPC and WPI affected the swelling behaviour of normal and waxy rice starch differently. A dramatic increase in the swelling of normal rice starch/MPC or WPI mixtures was observed, whereas this trend was not evident for waxy rice starch/ MPC or WPI mixtures. The difference in the water holding ability and gelatinization peak temperatures of the two starches over the temperature range at which whey proteins denature and form gels are believed to be responsible for the observed differences. The results from confocal microscopy showed that milk proteins, such as a-casein, ß- casein, ß-lg and a-lactalbumin (a-la), were adsorbed onto the granule surface of both normal and waxy rice starch. The mechanism for this adsorption is the hydrophilic interactions; hydrogen bonds between hydroxyl group from terminated glucan molecule that protrude around starch granule surface-hydroxyl; amino, or other electron-donation or electron-accepting groups of the added proteins. Using sodium dodecyl sulfatepolyacrylamide gel electrophoresis (SDS-PAGE) it was found that for SMP and MPC the adsorbed as- to ß-casein ratio on both starches was similar to the as-casein to ß- casein ratio in the casein micelle at low SMP and MPC concentrations. But at high concentrations of SMP or MPC, this ratio decreased indicating that more ß-casein was adsorbed preferentially to as-casein. In the case of NaCAS, as-casein was adsorbed preferentially to ß-casein. Moreover, there was evidence of multilayer adsorption of ascasein into the surface of rice starch granules. Compared to the other milk protein ingredients, very small amounts of the ß-lg and a-la from WPI were adsorbed onto starch granules. However, the adsorbed amounts of ß-lg and a-la from WPI continuously increased with increasing WPI concentration, suggesting that these two proteins, particularly ß-lg, adsorbed in multilayers too.

The overall aim of this thesis is to determine if the interactions between normal and waxy rice starch and milk proteins from four milk protein ingredients, namely skim milk powder (SMP), milk protein concentrate (MPC), sodium caseinate (NaCAS) and whey protein isolate (WPI) do occur, and to identify the mechanisms underlying these interactions. Different milk protein ingredients at various concentrations (0 to 10%, w/w) affected markedly and differently the pasting behaviour of 10% (w/w) rice starches. SMP delayed the pasting of both rice starches by increasing the onset temperature (Tonset) and the peak viscosity temperature (Tpeak) of pasting. This was mainly due to the presence of lactose and ions, which was further supported by the investigation of the effects of UFSMP (a solution of salts and lactose present in SMP at their proper concentration) and lactose. The addition of NaCAS also delayed the pasting of rice starch; Tpeak in the case of both starches was increased. For normal rice starch paste, MPC and WPI decreased the Tpeak. MPC had no affect on Tpeak of waxy rice starch paste. The qualitative viscoelastic behaviour of rice starch/milk protein ingredient gels obtained from the above pastes was dominated by the continuous phase made of the starch molecules. There was evidence, as indicated by confocal microscopy, of phase separation between the milk proteins of SMP and MPC and the two starches. The phase separation was not observed in the addition of either NaCAS or WPI. Studies on the thermal behaviour of rice starch/milk protein ingredient mixtures by differential scanning calorimetry (DSC) showed that SMP, similarly to UFSMP, delayed the gelatinization of both starches. NaCAS also delayed the gelatinisation of both starches but had a greater effect on waxy than normal rice starch. The addition of NaCAS did not affect Tonset but increased Tpeak for normal rice starch, whereas the gelatinisation temperature of waxy rice starch was highly affected by the addition of NaCAS with both Tonset and Tpeak shifted to higher temperatures. MPC had no affect on the gelatinization temperature of normal rice starch, whereas the gelatinization temperature of waxy rice starch was increased by the addition of MPC. The addition of WPI to both rice starches showed two thermal transitions. The first of these was due to the gelatinisation of the starches and the second to the denaturation of ß-lactoglobulin (ß-lg). The addition of WPI to normal rice starch showed that the thermal behaviour of normal starch and protein were independent from each other. In contrast, the thermal behaviour of waxy rice starch was modified by the addition of WPI; both Tonset and Tpeak were increased. SMP decreased the Tonset of swelling, swelling ratio and the amount of starch leaching from both starches. These observed changes were due to the presence of lactose and ions in SMP. NaCAS slightly increased Tonset of swelling but the amount of starch leaching was reduced for both rice starches. The rigidity of both starches tended to increase in the presence of NaCAS. MPC and WPI affected the swelling behaviour of normal and waxy rice starch differently. A dramatic increase in the swelling of normal rice starch/MPC or WPI mixtures was observed, whereas this trend was not evident for waxy rice starch/ MPC or WPI mixtures. The difference in the water holding ability and gelatinization peak temperatures of the two starches over the temperature range at which whey proteins denature and form gels are believed to be responsible for the observed differences. The results from confocal microscopy showed that milk proteins, such as a-casein, ß- casein, ß-lg and a-lactalbumin (a-la), were adsorbed onto the granule surface of both normal and waxy rice starch. The mechanism for this adsorption is the hydrophilic interactions; hydrogen bonds between hydroxyl group from terminated glucan molecule that protrude around starch granule surface-hydroxyl; amino, or other electron-donation or electron-accepting groups of the added proteins. Using sodium dodecyl sulfatepolyacrylamide gel electrophoresis (SDS-PAGE) it was found that for SMP and MPC the adsorbed as- to ß-casein ratio on both starches was similar to the as-casein to ß- casein ratio in the casein micelle at low SMP and MPC concentrations. But at high concentrations of SMP or MPC, this ratio decreased indicating that more ß-casein was adsorbed preferentially to as-casein. In the case of NaCAS, as-casein was adsorbed preferentially to ß-casein. Moreover, there was evidence of multilayer adsorption of ascasein into the surface of rice starch granules. Compared to the other milk protein ingredients, very small amounts of the ß-lg and a-la from WPI were adsorbed onto starch granules. However, the adsorbed amounts of ß-lg and a-la from WPI continuously increased with increasing WPI concentration, suggesting that these two proteins, particularly ß-lg, adsorbed in multilayers too.

The overall aim of this thesis is to determine if the interactions between normal and waxy rice starch and milk proteins from four milk protein ingredients, namely skim milk powder (SMP), milk protein concentrate (MPC), sodium caseinate (NaCAS) and whey protein isolate (WPI) do occur, and to identify the mechanisms underlying these interactions. Different milk protein ingredients at various concentrations (0 to 10%, w/w) affected markedly and differently the pasting behaviour of 10% (w/w) rice starches. SMP delayed the pasting of both rice starches by increasing the onset temperature (Tonset) and the peak viscosity temperature (Tpeak) of pasting. This was mainly due to the presence of lactose and ions, which was further supported by the investigation of the effects of UFSMP (a solution of salts and lactose present in SMP at their proper concentration) and lactose. The addition of NaCAS also delayed the pasting of rice starch; Tpeak in the case of both starches was increased. For normal rice starch paste, MPC and WPI decreased the Tpeak. MPC had no affect on Tpeak of waxy rice starch paste. The qualitative viscoelastic behaviour of rice starch/milk protein ingredient gels obtained from the above pastes was dominated by the continuous phase made of the starch molecules. There was evidence, as indicated by confocal microscopy, of phase separation between the milk proteins of SMP and MPC and the two starches. The phase separation was not observed in the addition of either NaCAS or WPI. Studies on the thermal behaviour of rice starch/milk protein ingredient mixtures by differential scanning calorimetry (DSC) showed that SMP, similarly to UFSMP, delayed the gelatinization of both starches. NaCAS also delayed the gelatinisation of both starches but had a greater effect on waxy than normal rice starch. The addition of NaCAS did not affect Tonset but increased Tpeak for normal rice starch, whereas the gelatinisation temperature of waxy rice starch was highly affected by the addition of NaCAS with both Tonset and Tpeak shifted to higher temperatures. MPC had no affect on the gelatinization temperature of normal rice starch, whereas the gelatinization temperature of waxy rice starch was increased by the addition of MPC. The addition of WPI to both rice starches showed two thermal transitions. The first of these was due to the gelatinisation of the starches and the second to the denaturation of ß-lactoglobulin (ß-lg). The addition of WPI to normal rice starch showed that the thermal behaviour of normal starch and protein were independent from each other. In contrast, the thermal behaviour of waxy rice starch was modified by the addition of WPI; both Tonset and Tpeak were increased. SMP decreased the Tonset of swelling, swelling ratio and the amount of starch leaching from both starches. These observed changes were due to the presence of lactose and ions in SMP. NaCAS slightly increased Tonset of swelling but the amount of starch leaching was reduced for both rice starches. The rigidity of both starches tended to increase in the presence of NaCAS. MPC and WPI affected the swelling behaviour of normal and waxy rice starch differently. A dramatic increase in the swelling of normal rice starch/MPC or WPI mixtures was observed, whereas this trend was not evident for waxy rice starch/ MPC or WPI mixtures. The difference in the water holding ability and gelatinization peak temperatures of the two starches over the temperature range at which whey proteins denature and form gels are believed to be responsible for the observed differences. The results from confocal microscopy showed that milk proteins, such as a-casein, ß- casein, ß-lg and a-lactalbumin (a-la), were adsorbed onto the granule surface of both normal and waxy rice starch. The mechanism for this adsorption is the hydrophilic interactions; hydrogen bonds between hydroxyl group from terminated glucan molecule that protrude around starch granule surface-hydroxyl; amino, or other electron-donation or electron-accepting groups of the added proteins. Using sodium dodecyl sulfatepolyacrylamide gel electrophoresis (SDS-PAGE) it was found that for SMP and MPC the adsorbed as- to ß-casein ratio on both starches was similar to the as-casein to ß- casein ratio in the casein micelle at low SMP and MPC concentrations. But at high concentrations of SMP or MPC, this ratio decreased indicating that more ß-casein was adsorbed preferentially to as-casein. In the case of NaCAS, as-casein was adsorbed preferentially to ß-casein. Moreover, there was evidence of multilayer adsorption of ascasein into the surface of rice starch granules. Compared to the other milk protein ingredients, very small amounts of the ß-lg and a-la from WPI were adsorbed onto starch granules. However, the adsorbed amounts of ß-lg and a-la from WPI continuously increased with increasing WPI concentration, suggesting that these two proteins, particularly ß-lg, adsorbed in multilayers too.

The overall aim of this thesis is to determine if the interactions between normal and waxy rice starch and milk proteins from four milk protein ingredients, namely skim milk powder (SMP), milk protein concentrate (MPC), sodium caseinate (NaCAS) and whey protein isolate (WPI) do occur, and to identify the mechanisms underlying these interactions. Different milk protein ingredients at various concentrations (0 to 10%, w/w) affected markedly and differently the pasting behaviour of 10% (w/w) rice starches. SMP delayed the pasting of both rice starches by increasing the onset temperature (Tonset) and the peak viscosity temperature (Tpeak) of pasting. This was mainly due to the presence of lactose and ions, which was further supported by the investigation of the effects of UFSMP (a solution of salts and lactose present in SMP at their proper concentration) and lactose. The addition of NaCAS also delayed the pasting of rice starch; Tpeak in the case of both starches was increased. For normal rice starch paste, MPC and WPI decreased the Tpeak. MPC had no affect on Tpeak of waxy rice starch paste. The qualitative viscoelastic behaviour of rice starch/milk protein ingredient gels obtained from the above pastes was dominated by the continuous phase made of the starch molecules. There was evidence, as indicated by confocal microscopy, of phase separation between the milk proteins of SMP and MPC and the two starches. The phase separation was not observed in the addition of either NaCAS or WPI. Studies on the thermal behaviour of rice starch/milk protein ingredient mixtures by differential scanning calorimetry (DSC) showed that SMP, similarly to UFSMP, delayed the gelatinization of both starches. NaCAS also delayed the gelatinisation of both starches but had a greater effect on waxy than normal rice starch. The addition of NaCAS did not affect Tonset but increased Tpeak for normal rice starch, whereas the gelatinisation temperature of waxy rice starch was highly affected by the addition of NaCAS with both Tonset and Tpeak shifted to higher temperatures. MPC had no affect on the gelatinization temperature of normal rice starch, whereas the gelatinization temperature of waxy rice starch was increased by the addition of MPC. The addition of WPI to both rice starches showed two thermal transitions. The first of these was due to the gelatinisation of the starches and the second to the denaturation of ß-lactoglobulin (ß-lg). The addition of WPI to normal rice starch showed that the thermal behaviour of normal starch and protein were independent from each other. In contrast, the thermal behaviour of waxy rice starch was modified by the addition of WPI; both Tonset and Tpeak were increased. SMP decreased the Tonset of swelling, swelling ratio and the amount of starch leaching from both starches. These observed changes were due to the presence of lactose and ions in SMP. NaCAS slightly increased Tonset of swelling but the amount of starch leaching was reduced for both rice starches. The rigidity of both starches tended to increase in the presence of NaCAS. MPC and WPI affected the swelling behaviour of normal and waxy rice starch differently. A dramatic increase in the swelling of normal rice starch/MPC or WPI mixtures was observed, whereas this trend was not evident for waxy rice starch/ MPC or WPI mixtures. The difference in the water holding ability and gelatinization peak temperatures of the two starches over the temperature range at which whey proteins denature and form gels are believed to be responsible for the observed differences. The results from confocal microscopy showed that milk proteins, such as a-casein, ß- casein, ß-lg and a-lactalbumin (a-la), were adsorbed onto the granule surface of both normal and waxy rice starch. The mechanism for this adsorption is the hydrophilic interactions; hydrogen bonds between hydroxyl group from terminated glucan molecule that protrude around starch granule surface-hydroxyl; amino, or other electron-donation or electron-accepting groups of the added proteins. Using sodium dodecyl sulfatepolyacrylamide gel electrophoresis (SDS-PAGE) it was found that for SMP and MPC the adsorbed as- to ß-casein ratio on both starches was similar to the as-casein to ß- casein ratio in the casein micelle at low SMP and MPC concentrations. But at high concentrations of SMP or MPC, this ratio decreased indicating that more ß-casein was adsorbed preferentially to as-casein. In the case of NaCAS, as-casein was adsorbed preferentially to ß-casein. Moreover, there was evidence of multilayer adsorption of ascasein into the surface of rice starch granules. Compared to the other milk protein ingredients, very small amounts of the ß-lg and a-la from WPI were adsorbed onto starch granules. However, the adsorbed amounts of ß-lg and a-la from WPI continuously increased with increasing WPI concentration, suggesting that these two proteins, particularly ß-lg, adsorbed in multilayers too.

The overall aim of this thesis is to determine if the interactions between normal and waxy rice starch and milk proteins from four milk protein ingredients, namely skim milk powder (SMP), milk protein concentrate (MPC), sodium caseinate (NaCAS) and whey protein isolate (WPI) do occur, and to identify the mechanisms underlying these interactions. Different milk protein ingredients at various concentrations (0 to 10%, w/w) affected markedly and differently the pasting behaviour of 10% (w/w) rice starches. SMP delayed the pasting of both rice starches by increasing the onset temperature (Tonset) and the peak viscosity temperature (Tpeak) of pasting. This was mainly due to the presence of lactose and ions, which was further supported by the investigation of the effects of UFSMP (a solution of salts and lactose present in SMP at their proper concentration) and lactose. The addition of NaCAS also delayed the pasting of rice starch; Tpeak in the case of both starches was increased. For normal rice starch paste, MPC and WPI decreased the Tpeak. MPC had no affect on Tpeak of waxy rice starch paste. The qualitative viscoelastic behaviour of rice starch/milk protein ingredient gels obtained from the above pastes was dominated by the continuous phase made of the starch molecules. There was evidence, as indicated by confocal microscopy, of phase separation between the milk proteins of SMP and MPC and the two starches. The phase separation was not observed in the addition of either NaCAS or WPI. Studies on the thermal behaviour of rice starch/milk protein ingredient mixtures by differential scanning calorimetry (DSC) showed that SMP, similarly to UFSMP, delayed the gelatinization of both starches. NaCAS also delayed the gelatinisation of both starches but had a greater effect on waxy than normal rice starch. The addition of NaCAS did not affect Tonset but increased Tpeak for normal rice starch, whereas the gelatinisation temperature of waxy rice starch was highly affected by the addition of NaCAS with both Tonset and Tpeak shifted to higher temperatures. MPC had no affect on the gelatinization temperature of normal rice starch, whereas the gelatinization temperature of waxy rice starch was increased by the addition of MPC. The addition of WPI to both rice starches showed two thermal transitions. The first of these was due to the gelatinisation of the starches and the second to the denaturation of ß-lactoglobulin (ß-lg). The addition of WPI to normal rice starch showed that the thermal behaviour of normal starch and protein were independent from each other. In contrast, the thermal behaviour of waxy rice starch was modified by the addition of WPI; both Tonset and Tpeak were increased. SMP decreased the Tonset of swelling, swelling ratio and the amount of starch leaching from both starches. These observed changes were due to the presence of lactose and ions in SMP. NaCAS slightly increased Tonset of swelling but the amount of starch leaching was reduced for both rice starches. The rigidity of both starches tended to increase in the presence of NaCAS. MPC and WPI affected the swelling behaviour of normal and waxy rice starch differently. A dramatic increase in the swelling of normal rice starch/MPC or WPI mixtures was observed, whereas this trend was not evident for waxy rice starch/ MPC or WPI mixtures. The difference in the water holding ability and gelatinization peak temperatures of the two starches over the temperature range at which whey proteins denature and form gels are believed to be responsible for the observed differences. The results from confocal microscopy showed that milk proteins, such as a-casein, ß- casein, ß-lg and a-lactalbumin (a-la), were adsorbed onto the granule surface of both normal and waxy rice starch. The mechanism for this adsorption is the hydrophilic interactions; hydrogen bonds between hydroxyl group from terminated glucan molecule that protrude around starch granule surface-hydroxyl; amino, or other electron-donation or electron-accepting groups of the added proteins. Using sodium dodecyl sulfatepolyacrylamide gel electrophoresis (SDS-PAGE) it was found that for SMP and MPC the adsorbed as- to ß-casein ratio on both starches was similar to the as-casein to ß- casein ratio in the casein micelle at low SMP and MPC concentrations. But at high concentrations of SMP or MPC, this ratio decreased indicating that more ß-casein was adsorbed preferentially to as-casein. In the case of NaCAS, as-casein was adsorbed preferentially to ß-casein. Moreover, there was evidence of multilayer adsorption of ascasein into the surface of rice starch granules. Compared to the other milk protein ingredients, very small amounts of the ß-lg and a-la from WPI were adsorbed onto starch granules. However, the adsorbed amounts of ß-lg and a-la from WPI continuously increased with increasing WPI concentration, suggesting that these two proteins, particularly ß-lg, adsorbed in multilayers too.

The overall aim of this thesis is to determine if the interactions between normal and waxy rice starch and milk proteins from four milk protein ingredients, namely skim milk powder (SMP), milk protein concentrate (MPC), sodium caseinate (NaCAS) and whey protein isolate (WPI) do occur, and to identify the mechanisms underlying these interactions. Different milk protein ingredients at various concentrations (0 to 10%, w/w) affected markedly and differently the pasting behaviour of 10% (w/w) rice starches. SMP delayed the pasting of both rice starches by increasing the onset temperature (Tonset) and the peak viscosity temperature (Tpeak) of pasting. This was mainly due to the presence of lactose and ions, which was further supported by the investigation of the effects of UFSMP (a solution of salts and lactose present in SMP at their proper concentration) and lactose. The addition of NaCAS also delayed the pasting of rice starch; Tpeak in the case of both starches was increased. For normal rice starch paste, MPC and WPI decreased the Tpeak. MPC had no affect on Tpeak of waxy rice starch paste. The qualitative viscoelastic behaviour of rice starch/milk protein ingredient gels obtained from the above pastes was dominated by the continuous phase made of the starch molecules. There was evidence, as indicated by confocal microscopy, of phase separation between the milk proteins of SMP and MPC and the two starches. The phase separation was not observed in the addition of either NaCAS or WPI. Studies on the thermal behaviour of rice starch/milk protein ingredient mixtures by differential scanning calorimetry (DSC) showed that SMP, similarly to UFSMP, delayed the gelatinization of both starches. NaCAS also delayed the gelatinisation of both starches but had a greater effect on waxy than normal rice starch. The addition of NaCAS did not affect Tonset but increased Tpeak for normal rice starch, whereas the gelatinisation temperature of waxy rice starch was highly affected by the addition of NaCAS with both Tonset and Tpeak shifted to higher temperatures. MPC had no affect on the gelatinization temperature of normal rice starch, whereas the gelatinization temperature of waxy rice starch was increased by the addition of MPC. The addition of WPI to both rice starches showed two thermal transitions. The first of these was due to the gelatinisation of the starches and the second to the denaturation of ß-lactoglobulin (ß-lg). The addition of WPI to normal rice starch showed that the thermal behaviour of normal starch and protein were independent from each other. In contrast, the thermal behaviour of waxy rice starch was modified by the addition of WPI; both Tonset and Tpeak were increased. SMP decreased the Tonset of swelling, swelling ratio and the amount of starch leaching from both starches. These observed changes were due to the presence of lactose and ions in SMP. NaCAS slightly increased Tonset of swelling but the amount of starch leaching was reduced for both rice starches. The rigidity of both starches tended to increase in the presence of NaCAS. MPC and WPI affected the swelling behaviour of normal and waxy rice starch differently. A dramatic increase in the swelling of normal rice starch/MPC or WPI mixtures was observed, whereas this trend was not evident for waxy rice starch/ MPC or WPI mixtures. The difference in the water holding ability and gelatinization peak temperatures of the two starches over the temperature range at which whey proteins denature and form gels are believed to be responsible for the observed differences. The results from confocal microscopy showed that milk proteins, such as a-casein, ß- casein, ß-lg and a-lactalbumin (a-la), were adsorbed onto the granule surface of both normal and waxy rice starch. The mechanism for this adsorption is the hydrophilic interactions; hydrogen bonds between hydroxyl group from terminated glucan molecule that protrude around starch granule surface-hydroxyl; amino, or other electron-donation or electron-accepting groups of the added proteins. Using sodium dodecyl sulfatepolyacrylamide gel electrophoresis (SDS-PAGE) it was found that for SMP and MPC the adsorbed as- to ß-casein ratio on both starches was similar to the as-casein to ß- casein ratio in the casein micelle at low SMP and MPC concentrations. But at high concentrations of SMP or MPC, this ratio decreased indicating that more ß-casein was adsorbed preferentially to as-casein. In the case of NaCAS, as-casein was adsorbed preferentially to ß-casein. Moreover, there was evidence of multilayer adsorption of ascasein into the surface of rice starch granules. Compared to the other milk protein ingredients, very small amounts of the ß-lg and a-la from WPI were adsorbed onto starch granules. However, the adsorbed amounts of ß-lg and a-la from WPI continuously increased with increasing WPI concentration, suggesting that these two proteins, particularly ß-lg, adsorbed in multilayers too.

The overall aim of this thesis is to determine if the interactions between normal and waxy rice starch and milk proteins from four milk protein ingredients, namely skim milk powder (SMP), milk protein concentrate (MPC), sodium caseinate (NaCAS) and whey protein isolate (WPI) do occur, and to identify the mechanisms underlying these interactions. Different milk protein ingredients at various concentrations (0 to 10%, w/w) affected markedly and differently the pasting behaviour of 10% (w/w) rice starches. SMP delayed the pasting of both rice starches by increasing the onset temperature (Tonset) and the peak viscosity temperature (Tpeak) of pasting. This was mainly due to the presence of lactose and ions, which was further supported by the investigation of the effects of UFSMP (a solution of salts and lactose present in SMP at their proper concentration) and lactose. The addition of NaCAS also delayed the pasting of rice starch; Tpeak in the case of both starches was increased. For normal rice starch paste, MPC and WPI decreased the Tpeak. MPC had no affect on Tpeak of waxy rice starch paste. The qualitative viscoelastic behaviour of rice starch/milk protein ingredient gels obtained from the above pastes was dominated by the continuous phase made of the starch molecules. There was evidence, as indicated by confocal microscopy, of phase separation between the milk proteins of SMP and MPC and the two starches. The phase separation was not observed in the addition of either NaCAS or WPI. Studies on the thermal behaviour of rice starch/milk protein ingredient mixtures by differential scanning calorimetry (DSC) showed that SMP, similarly to UFSMP, delayed the gelatinization of both starches. NaCAS also delayed the gelatinisation of both starches but had a greater effect on waxy than normal rice starch. The addition of NaCAS did not affect Tonset but increased Tpeak for normal rice starch, whereas the gelatinisation temperature of waxy rice starch was highly affected by the addition of NaCAS with both Tonset and Tpeak shifted to higher temperatures. MPC had no affect on the gelatinization temperature of normal rice starch, whereas the gelatinization temperature of waxy rice starch was increased by the addition of MPC. The addition of WPI to both rice starches showed two thermal transitions. The first of these was due to the gelatinisation of the starches and the second to the denaturation of ß-lactoglobulin (ß-lg). The addition of WPI to normal rice starch showed that the thermal behaviour of normal starch and protein were independent from each other. In contrast, the thermal behaviour of waxy rice starch was modified by the addition of WPI; both Tonset and Tpeak were increased. SMP decreased the Tonset of swelling, swelling ratio and the amount of starch leaching from both starches. These observed changes were due to the presence of lactose and ions in SMP. NaCAS slightly increased Tonset of swelling but the amount of starch leaching was reduced for both rice starches. The rigidity of both starches tended to increase in the presence of NaCAS. MPC and WPI affected the swelling behaviour of normal and waxy rice starch differently. A dramatic increase in the swelling of normal rice starch/MPC or WPI mixtures was observed, whereas this trend was not evident for waxy rice starch/ MPC or WPI mixtures. The difference in the water holding ability and gelatinization peak temperatures of the two starches over the temperature range at which whey proteins denature and form gels are believed to be responsible for the observed differences. The results from confocal microscopy showed that milk proteins, such as a-casein, ß- casein, ß-lg and a-lactalbumin (a-la), were adsorbed onto the granule surface of both normal and waxy rice starch. The mechanism for this adsorption is the hydrophilic interactions; hydrogen bonds between hydroxyl group from terminated glucan molecule that protrude around starch granule surface-hydroxyl; amino, or other electron-donation or electron-accepting groups of the added proteins. Using sodium dodecyl sulfatepolyacrylamide gel electrophoresis (SDS-PAGE) it was found that for SMP and MPC the adsorbed as- to ß-casein ratio on both starches was similar to the as-casein to ß- casein ratio in the casein micelle at low SMP and MPC concentrations. But at high concentrations of SMP or MPC, this ratio decreased indicating that more ß-casein was adsorbed preferentially to as-casein. In the case of NaCAS, as-casein was adsorbed preferentially to ß-casein. Moreover, there was evidence of multilayer adsorption of ascasein into the surface of rice starch granules. Compared to the other milk protein ingredients, very small amounts of the ß-lg and a-la from WPI were adsorbed onto starch granules. However, the adsorbed amounts of ß-lg and a-la from WPI continuously increased with increasing WPI concentration, suggesting that these two proteins, particularly ß-lg, adsorbed in multilayers too.

The overall aim of this thesis is to determine if the interactions between normal and waxy rice starch and milk proteins from four milk protein ingredients, namely skim milk powder (SMP), milk protein concentrate (MPC), sodium caseinate (NaCAS) and whey protein isolate (WPI) do occur, and to identify the mechanisms underlying these interactions. Different milk protein ingredients at various concentrations (0 to 10%, w/w) affected markedly and differently the pasting behaviour of 10% (w/w) rice starches. SMP delayed the pasting of both rice starches by increasing the onset temperature (Tonset) and the peak viscosity temperature (Tpeak) of pasting. This was mainly due to the presence of lactose and ions, which was further supported by the investigation of the effects of UFSMP (a solution of salts and lactose present in SMP at their proper concentration) and lactose. The addition of NaCAS also delayed the pasting of rice starch; Tpeak in the case of both starches was increased. For normal rice starch paste, MPC and WPI decreased the Tpeak. MPC had no affect on Tpeak of waxy rice starch paste. The qualitative viscoelastic behaviour of rice starch/milk protein ingredient gels obtained from the above pastes was dominated by the continuous phase made of the starch molecules. There was evidence, as indicated by confocal microscopy, of phase separation between the milk proteins of SMP and MPC and the two starches. The phase separation was not observed in the addition of either NaCAS or WPI. Studies on the thermal behaviour of rice starch/milk protein ingredient mixtures by differential scanning calorimetry (DSC) showed that SMP, similarly to UFSMP, delayed the gelatinization of both starches. NaCAS also delayed the gelatinisation of both starches but had a greater effect on waxy than normal rice starch. The addition of NaCAS did not affect Tonset but increased Tpeak for normal rice starch, whereas the gelatinisation temperature of waxy rice starch was highly affected by the addition of NaCAS with both Tonset and Tpeak shifted to higher temperatures. MPC had no affect on the gelatinization temperature of normal rice starch, whereas the gelatinization temperature of waxy rice starch was increased by the addition of MPC. The addition of WPI to both rice starches showed two thermal transitions. The first of these was due to the gelatinisation of the starches and the second to the denaturation of ß-lactoglobulin (ß-lg). The addition of WPI to normal rice starch showed that the thermal behaviour of normal starch and protein were independent from each other. In contrast, the thermal behaviour of waxy rice starch was modified by the addition of WPI; both Tonset and Tpeak were increased. SMP decreased the Tonset of swelling, swelling ratio and the amount of starch leaching from both starches. These observed changes were due to the presence of lactose and ions in SMP. NaCAS slightly increased Tonset of swelling but the amount of starch leaching was reduced for both rice starches. The rigidity of both starches tended to increase in the presence of NaCAS. MPC and WPI affected the swelling behaviour of normal and waxy rice starch differently. A dramatic increase in the swelling of normal rice starch/MPC or WPI mixtures was observed, whereas this trend was not evident for waxy rice starch/ MPC or WPI mixtures. The difference in the water holding ability and gelatinization peak temperatures of the two starches over the temperature range at which whey proteins denature and form gels are believed to be responsible for the observed differences. The results from confocal microscopy showed that milk proteins, such as a-casein, ß- casein, ß-lg and a-lactalbumin (a-la), were adsorbed onto the granule surface of both normal and waxy rice starch. The mechanism for this adsorption is the hydrophilic interactions; hydrogen bonds between hydroxyl group from terminated glucan molecule that protrude around starch granule surface-hydroxyl; amino, or other electron-donation or electron-accepting groups of the added proteins. Using sodium dodecyl sulfatepolyacrylamide gel electrophoresis (SDS-PAGE) it was found that for SMP and MPC the adsorbed as- to ß-casein ratio on both starches was similar to the as-casein to ß- casein ratio in the casein micelle at low SMP and MPC concentrations. But at high concentrations of SMP or MPC, this ratio decreased indicating that more ß-casein was adsorbed preferentially to as-casein. In the case of NaCAS, as-casein was adsorbed preferentially to ß-casein. Moreover, there was evidence of multilayer adsorption of ascasein into the surface of rice starch granules. Compared to the other milk protein ingredients, very small amounts of the ß-lg and a-la from WPI were adsorbed onto starch granules. However, the adsorbed amounts of ß-lg and a-la from WPI continuously increased with increasing WPI concentration, suggesting that these two proteins, particularly ß-lg, adsorbed in multilayers too.