Sucrose esters have an established use in food industry as emulsifiers. Two novel lactose esters (lactose monodecanoate and lactose monomyristate) were synthesized and studied for their antimicrobial and emulsification properties. Lactose is a byproduct in cheese production and is an inexpensive carbohydrate source. The antimicrobial activity of lactose monodecanoate (LMD) and lactose monomyristate (LMM) was tested against the growth of seven different bacteria. Both esters, when dissolved in dimethoxy sulfoxide (DMSO), proved bactericidal against Bacillus cereus, Mycobacteria KMS and Streptococcus suis. LMM/DMSO was bactericidal against B. cereus at concentrations between 1 and 3 mg/ml. LMM/DMSO was bactericidal against M. KMS and S. suis at concentrations between 3 and 5 mg/ml. LMD/DMSO was bactericidal against B. cereus and S. suis at concentrations between 1 and 3 mg/ml and against M. KMS at concentrations between 0.1 and 1 mg/ml. LMM/DMSO and LMD/DMSO were not effective in inhibiting the growth of Listeria monocyotgenes and Enterococcus faecalis. The antimicrobial effects of LMD on the growth of Listeria monocytogenes and Enterococcus faecalis were found to be solvent dependent. LMD, when dissolved in 30% ethanol, was able to inhibit the growth of L. monocytogenes at concentration between 1 and 3 mg/ml and E. faecalis at concentration between 3 and 5 mg/ml. The growth of Streptococcus mutans and Escherichia coli O157:H7 remained unaltered in the presence of LMD/ETOH, LMD/DMSO and LMM/DMSO up to 5 mg/ml. LMM was also analyzed for its emulsification properties. The destabilization rates and droplet size of the emulsion were determined for five consecutive days. At a concentration of 0.5%, LMM produced 20% oil in water emulsion with destabilization rate of 1.1 mm/day, which can be considered a stable emulsion. The droplet size of the emulsion was also within the range of 0-10 μm. Lower droplet size range signifies the effective work of the LMM as an emulsifier. Also the droplet size of the emulsion was found to be consistent over five days, which is indicative of a stable emulsion.

Sugar esters, substances made from bonding fatty acid tails to a sugar head, can play a number of key roles in food systems from antimicrobial agents to emulsifiers. These unique and very useful properties result from their water-loving and water-avoiding ends. Lactose, a sugar found in milk, based esters are important, as they are environmentally friendly and inexpensive, however, they are not very well understood. I created four different types of lactose esters: lactose monooctanoate (LMO), lactose monodecanoate (LMD), lactose monolaurate (LML) and lactose monomyristate (LMM), and then compared them to each other to see which would be the best emulsifier and which would be the best antimicrobial. My previous studies showed that LML was inhibitory against Listeria monocytogenes a common food pathogen. This encouraged us to evaluated the microbial inhibitory (bacterial killing) properties of LMO, LMD, LMM, along with LML, specifically, the influence of the fatty acid chain length in each ester and how that influenced my results. The esters, in order of highest microbial inhibitory properties, were LML, LMD, LMM followed by LMO. LML was inhibitory against all the Gram- positive bacteria tested including Bacillus cereus, Mycobacterium KMS, Streptococcussuis, L. monocytogenes, Enterococcus faecalis, and Streptococcus mutans but not Gram-negative bacteria (Escherichia coli O157:H7). Sugar esters are a large class of emulsifiers used in the food industry, and so my second research objective was to evaluate the influence of the fatty acid chain length on the emulsification properties of LMO, LMD, LML and LMM and compare them to each other and controls (Tween-20 and Ryoto L-1695) in a standard oil-in-water (O/W) emulsion. I did this by observing how long my emulsions lasted after mixing before they would start to separate. I also looked at the actual size of the oil drops in each of my emulsions, the smaller the oil drops remained, the better they stay in the emulsion and thus the more stable the emulsion. My results showed that the best emulsifier was LML, followed by LMD, LMM, and LMO, respectively. Therefore, my lactose esters contained both microbial inhibitory and emulsification activities. L. monocytogenes is an infamous food pathogen and one of the largest sources of food-borne illness from dairy foods in the United States. Addition of LMD and LML previously were shown to have microbial inhibitory effects in my lab so I wanted to see how well they would work in a food: milk. In general, bacterial deaths in the LMD milk samples were great and many times greater than the LML samples. However, both were greatly affected by milk fat content and how warm each of the samples were kept. LMD may play a useful role in increasing the safety of some foods.

Flaxseed (Linum usitatissimum L.) gum (FG) is a material with many potential food and non-food applications. Consistent performance is critical for FG utilization and this is possible through selection of genotype, characterization and optimization of constituents, and chemical modification. Physico-chemical and functional properties of FG aqueous solutions from six Canadian flaxseed cultivars were investigated. FG yield, carbohydrate composition, protein content, and zeta potential (ζ) varied among these cultivars. FG solution properties were also affected by temperature, solution pH, NaCl concentration, and sucrose concentration. Detailed studies were conducted on CDC Bethune FG (FGB) proteins that were separated by 2D-gel electrophoresis. Conlinin was identified as the major protein. Protease treatment decreased FGB solution emulsification properties suggesting that conlinin might enhance emulsification. Formation of BSA-FGB coacervates was monitored by turbidimetric analysis as a function of solution pH, biopolymer mixing ratio, NaCl and urea. Coacervates were stabilized primarily by attractive electrostatic forces and secondarily by hydrogen bonds. Further, anionic carboxymethyl ether moieties were introduced to FGB structure through ether forming reactions using monochloroacetic acid (MCA) to produce products with uniform properties. The highest degree of substitution (DS) was obtained at 70 °C, 7.0 M NaOH, and a molar ratio of MCA to FGB of 10:1 over 3 h. Carboxymethylated FGB (CMFG) exhibited both modified surface morphology and thermal behaviour. Solutions of CMFG demonstrated shear-thinning behaviour and apparent viscosity decreased with increased DS. A more liquid-like flow behaviour was observed for CMFG as DS increased. Findings here will introduce and expand FG applications in food or related fields with targeted performance.