Transformations in the properties of low-moisture dough products (cookies and crackers) during baking have been studied under idealized conditions in pilot facilities and laboratories. However, little research is published that describes dough development within the context of complex industrial baking processes. A process mapping approach was adopted, in which oven parameters were profiled and matched against changes in dough. In cookies, changes to starch A-granules, including loss of granule birefringence, disruption to granule borders and increased gel viscosity were observed. Development of acrylamide in cookies was seen to trail colour development, suggesting options for mediating acrylamide content. In crackers, the presence of additional water allowed significant changes to starch A-granules to occur, including: swelling similar to the early stages of gelatinization in bread, reduced pasting ability, a drop in enthalpy, and a loss of crystallinity. Emulation of low-moisture dough baking at the benchtop level, based upon internal product temperature data from industrial processes, was found to be limited in its ability to produce crackers having appropriate leavening and internal structure development. The determination of isosteric heat of desorption values for cookies and crackers, modeled on industrial processes at temperatures > 100°C, gave values of 44.3 and 42.7 kJ/mol, respectively. This data will be useful for establishing energy requirements in industrial baking processes / MITACS, OMAFRA

Salmonella and Cronobacter sakazakii are two leading causes of foodborne illness associated with low-moisture foods, including infant formula. Both causative organisms can persist in food manufacturing processing environments and contaminate finished product if programs are not in place to limit their introduction and control their spread. An environmental sampling and monitoring program is an important tool that food manufacturers use to determine the effectiveness of their sanitation practices and pathogen control efforts. Guidance for initiating an environmental sampling plan and evaluating the plan is lacking. The objective of this study was to develop microbiological environmental sampling plans based on the answers to a series of questions related to product hazards, processing risks and controls, and knowledge of appropriate microbiological sampling and testing protocols. Furthermore, these initial sampling plans were related to the volume of product and size of the processing facility.  An interactive spreadsheet tool for designing sampling monitoring plans for an infant formula process was developed using Microsoft Excel. Additionally, the tool can be used to record qualitative and quantitative sample test results, and to alert the user how the upcoming sampling plan will be changed, if necessary, based on monthly test summaries. The sampling tool provides a simple method for selecting an appropriate environmental sampling plan (samples per zone per month) and provides a rationale and guidance for creating and modifying these plans.  Effective sampling plans and trend analysis of sample test results support the food processors decisions for implementing controls to enhance food safety. / Master of Science in Life Sciences

Master of Science / Department of Animal Sciences and Industry / J.S. Drouillard / Three studies were conducted to investigate alternative ingredients and processing methods for manufacturing low-moisture blocks. Study 1 was designed to determine if ruminal lactate could be transiently increased by feeding fructose-based blocks to heifers fed prairie hay, thus providing substrate for establishment of lactate utilizing microbes. Low-moisture blocks comprised of 96% fructose and 4% vegetable oil (DM basis) were manufactured and dosed via ruminal fistulas. Administration of fructose blocks resulted in transient increases in ruminal lactate (P < 0.05), accompanied by transient decreases in pH (P < 0.05). Ruminal fluid incubated with semi-defined lactate medium became more turbid (P < 0.05) as a result of prior exposure to fructose blocks suggesting greater capacity for lactate metabolism. In study 2 a portion of the molasses was replaced by corn steep liquor (CSL) or condensed corn distiller’s solubles (CCDS). Heifers were fed a forage-based diet and supplemented with 1 of 4 supplement blocks. Supplements were a 30% CP molasses block manufactured at ambient pressure and high temperatures (Mol-30). The remaining treatments were manufactured at reduced pressure and temperature and were a 30% CP block with 36% CSL (CSL-30); a 40% CP block with 40% CSL (CSL-40); or a 40% CP block with 25% CCDS (CCDS-40). Supplementing with Mol-30 and CSL-40 resulted in greater DMI (%BW) than with CCDS-40 (P < 0.05). Supplementing with CSL-30 improved efficiency and ADG compared to Mol-30 (P < 0.01). Study 3 evaluated the affect of cooking temperature on blocks containing CSL fed to heifers receiving a forage-based diet. Heifers were offered no supplement (Control) or a 15% CSL block manufactured at ambient pressure and high temperature (HT-15). The remaining treatments were manufactured at reduced pressure and temperature and were a 15% CSL block (LT-15); or 40% CSL block (LT-40). Control heifers had the lowest DMI and LT-40 had the greatest (P < 0.05). Feeding heifers LT-15 or LT-40 improved ADG compared to heifers fed HT-15 or no supplement (P < 0.05). Heifers fed LT-40 tended to be more efficient than those fed HT-15 and Control (P = 0.07).

Three serious problems have been experienced in the manufacture of low moisture cheese using ultrafiltration (UF)- high fat-loss, excessive moisture retention, and poor cheese texture. In this work the causes of these problems were identified, and means of overcoming them were developed. Coagulation and cheese-making experiments indicated that UF concentration of milk shifts the control of rennet coagulation toward the casein micelle collision rate and away from rennet activity, resulting in formation of a rough-textured curd structure that resists syneresis. Use of 4x whole milk retentate, instead of 5x, improved rennet curd structure, syneresis, and UF cheese texture without reducing protein retention in the cheese. Use of increased rennet and reduced set temperature (26°C) also improved curd structure, syneresis, and cheese texture. Washing of the rennet curd prepared from 4x milk retentate during cheese-making, instead of diafiltration of retentate, was found to improve cheese texture, and cheese moisture below 39% was achieved. UF retentate was inconsistent as a starter medium because it offered no protection against bacteriophage proliferation, and the growth of some strains of Lactococcus lactis was impaired in UF retentate. Commercial, internally-buffered pH-controlled starter media were more consistent than fermented retentate starter when used for making cheese from 4x retentate. Low-pressure homogenization of milk at a temperature between 37°C and 45°C increased fat recovery in UF cheese made from 4x ultrafiltration concentrated milk with minimal damage to cheese texture and syneresis. A procedure was developed for the manufacture of quality, high-yield, low-moisture cheese from 4 times ultrafiltration concentrated whole milk. Fat retention in the cheese was 95% and protein retention was 85%

In this study, we determined the effect of nutritive sweeteners at 0 to 0.50 moles/kg on lipid oxidation in a model cookie system. Confocal microscopy using Bodipy 493 as a fat soluble dye showed that the fat formed a continuous phase surrounding the starch granules regardless of sugar type. The impact of glucose concentration on lipid oxidation was monitored by lipid hydroperoxides and headspace hexanal during storage at 55°C. Low concentrations of glucose (0.09) were strong inhibitors. At equal molar concentrations, reducing sugars (glucose and fructose) inhibited lipid oxidation, greater than a two months increase in lag phase compared to the control. Sucrose inhibited lipid oxidation, but to a much lesser extent than reducing sugars. The inhibition of lipid oxidation is potentially due to sugar’s ability to bind water. Additionally, reducing sugars may exhibit this effect due to their ability to act as a hydrogen donor which could inactivate free radicals or due to the production of Maillard reaction products (MRPs). For example, the l-values were lower and b-values were higher for cookies with non-reducing sugars compared to cookies with sucrose indicating that there were more MRPs. The addition of cysteine, sulfites, and ascorbic acid acted as a strong browning inhibitors however cysteine was showed to be antioxidative. When compared to synthetic antioxidants, glucose proved to be a strong natural alternative. These results could be utilized to develop effective means of controlling water activity and extending shelf-life of low moisture baked goods.

Unsaturated fats undergo a process known as oxidation by which they are degraded into undesirable compounds. Therefore it is important for food manufacturers to employ antioxidant strategies. Crackers were used as a model in these studies because of their dietary contribution to saturated, and because the properties of crackers are translatable to other low moisture foods. The objective of this thesis was to determine if there was a significant variance in rates of oxidation between surface and total lipids in crackers and how solid fat content, synthetic antioxidants, and reduction of headspace oxygen affect those rates. It was hypothesized that lipids on the surface of a cracker would be more prone to oxidation than those on the interior. Experiments consisted of treatments to monitor total lipid oxidation and surface lipid oxidation. In the first experiment, crackers were formulated with soy oils of varying solid fat content. The second experiment monitored the effects of two synthetic antioxidants, BHT and TBHQ. The third experiment involved flushing the headspace of cracker storage vials with different blends of nitrogen and oxygen to inhibit lipid oxidation. Overall, significant differences did not exist in the rates of oxidation between surface and interior lipids. The lower the solid fat content of an oil, the more prone it was to oxidation. Antioxidants of greater hydrophobicity have increased efficacy in low moisture foods. Greater than 70% oxygen reduction is necessary to impart any antioxidant effect on crackers.

<p>Low moisture baked goods (cookies, biscuits, etc.) are known for their high sugar content, low water content, and characteristic texture. The added sugar in baked goods has been a concern of health advocates due to the negative health implications of overconsumption of sugar. To minimize these health implications and support healthier food products, the replacement of sugar, sucrose, in low moisture baked goods with alternative sweeteners is of interest. The goal of this study was to improve understanding on how sweetener alternatives and dietary fiber interact with cookie ingredients and the subsequent cookie texture compared to sucrose containing cookies to aid in developing health-conscious low moisture baked goods.</p><p> The replacement of sucrose with sucrose replacers (SRs) encompassing a variety of structural and physicochemical properties (high fructose corn syrup (HFCS), amorphous sucrose, maltitol, allulose, isomalt, Benefiber, Miralax, fructooligosaccharides (FOS), and isomalto-oligosacchrides (IMO)) in wire-cut cookies was investigated in terms of starch thermal properties, model cookie formulations, and sensory descriptive analysis. Starch thermal properties were investigated using differential scanning calorimetry (DSC) while wire-cut cookie parameters were analyzed through a_w, color (<i>a, b, L</i>), moisture loss, cookie dimensions (height, width, length), and cookie hardness (N) assays. Sensory descriptive analysis was used to ascertain texture perception of wire-cut cookies through five attributes (hardness, fracturability, pastiness, cohesiveness, and crumbliness).</p> The onset gelatinization temperature (T_gel) was increased to a greater extent than sucrose by Miralax and FOS, and to the same extent by IMO, maltitol, and Benefiber at high concentrations (60%w/w). The SRs which performed similar to sucrose in wire-cut cookie baking (spread, moisture loss, hardness) and texture intensity ratings were amorphous sucrose, maltitol, and allulose. No significant differences in descriptive analysis intensity scores were found in crumbliness, cohesiveness, and pastiness between SRs and sucrose formulated wire-cut cookies. FOS, IMO, and Benefiber displayed significantly larger fracture intensity scores compared so sucrose and isomalt cookies were significantly less hard than sucrose cookies. Principal component analysis (PCA) related SRs effect on starch gelatinization, cookie baking properties, and descriptive analysis intensity scores, and indicated the mostly likely candidates for use in reduced sugar cookies are maltitol and allulose.

Cronobacter sakazakii is a gram-negative opportunistic pathogen known to survive in dry environments and food matrices, such as infant formula. This foodborne bacterium can cause fatal human infections of the blood, central nervous system, and gastrointestinal tract; it is also problematic in wounds and urinary tract infections. Preterm infants and immunocompromised individuals are in higher risk categories related to necrotizing enterocolitis, neonatal sepsis, and meningitis due to this organism. Therefore, there is a need for increased understanding of how this bacterium is able to persist in thermally treated low-moisture products that do not support growth. The objective of this research is to identify genes and mechanisms in C. sakazakii that contribute to its resistance to desiccation and survival in low-moisture food matrices, including powdered infant formula. C. sakazakii sequence type 4 (ST4) is of particular interest as it is often the cause of neonatal infections originating from contaminated feedings of powder infant formula. The method chosen to explore these genetic patterns is massively parallel transposon insertion sequencing (Tn-seq). The E. coli strain MFDpir was used to facilitate transposon insertional mutagenesis to create a library of mutated C. sakazakii. Three different C. sakazakii ST4 isolates of different origins (clinical, environmental, and infant formula-derived) were selected for this study. Once transposon mutagenesis occurred with the aid of E. coli MFDpir, the three mutant libraries were subjected to desiccation stress in a closed system equilibrated to 11.3% relative humidity. The surviving mutant genomes were analyzed with Tn-seq. The sequencing data revealed that, while transposition events did occur successfully within the genomes of each of the selected C. sakazakii isolates, these events were not dense enough to draw biological conclusions nor statistical inferences concerning which genes contribute to this organism’s uncanny desiccation tolerance. However, we concluded that the Tn-seq method is a promising tool with this organism of interest, despite incomplete results in this first round of experimentation.

No description available.

The chemical composition of milk (specifically casein, fat, and calcium) is known to affect the quality and functional properties of Mozzarella cheese. Therefore, concentrations of total nitrogen, casein nitrogen, non-casein nitrogen, non-protein nitrogen, true nitrogen, casein nitrogen to total nitrogen ratio, casein nitrogen to true nitrogen ratio, fat, total calcium, total solids, somatic cells, and pH were measured in silo milk samples collected weekly over 18-months from a large dairy plant in Central Valley, California from July 2008 to December 2009 to verify changes and correlate to low moisture part skim Mozzarella (LMPS) characteristics. LMPS mozzarella cheese from the same plant was also collected biweekly during the same period and analyzed five days post manufacture for total nitrogen, water soluble nitrogen, total calcium, water soluble calcium, salt, pH, fat in dry matter and total solids and texture properties (i.e., hardness (g), cohesiveness, springiness, chewiness (g), aggregation index (AGI), and percentage cheese loss during shredding). Significant seasonal variations of total nitrogen, non-protein nitrogen, casein nitrogen, casein nitrogen to total nitrogen ratio, casein nitrogen to true nitrogen ratio, and total calcium in milk were explained using a linear model equivalent to a basic single cosinor model with sine and cosine of week (converted into radians) as predictors. Correlation studies were done between milk composition and cheese composition, milk composition and cheese textural characteristics as well as cheese composition and cheese texture, showing that concentration of total calcium and nitrogen fractions in cheese milk significantly affected the texture and composition of LMPS mozzarella. Also, the cheese total nitrogen, total calcium and water soluble calcium affected the cheese texture. The LMPS Mozzarella that was firmer and more cohesive had less loss during shredding and aggregated to a lesser extent. The milk total nitrogen, non-protein nitrogen, casein nitrogen, casein to total protein ratio, casein to true protein ratio, and total calcium had positive correlation with each other. However, the milk non-casein nitrogen did not significantly correlate with other nitrogen fractions and total calcium of milk. In addition, there was a significant increase of water soluble nitrogen, percent loss in shredding and aggregation index, and a significant decrease of hardness, and chewiness of LMPS Mozzarella ripened at 8.90 C in comparison to the cheese ripened at 3.30 C for 21 days.