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Probiotics are beneficial microbes often added to food products to enhance the health and wellness of consumers. A major limitation to producing efficacious functional foods containing probiotic cells is their tendency to lose viability during storage and gastrointestinal transit. In this study, the impact of encapsulating probiotics within food-grade hydrogel particles to mitigate sensitivity to environmental stresses was examined. Confocal fluorescence microscopy confirmed that Lactococcus lactis were trapped within calcium alginate beads formed by dripping a probiotic-alginate mixture into a calcium solution. Encapsulation improved the viability of the probiotics during aerobic storage: after seven days, less than a two-log reduction was observed in encapsulated cells stored at room temperature, demonstrating that a high concentration of cells survived relative to non-encapsulated bacteria. These hydrogel beads may have applications for improving the stability and efficacy of probiotics in functional foods.

The effects of high hydrostatic pressure (HHP) processing (at 200 to 600 MPa, 25 to 55 degrees C, and from 5 to 15 min) on some structural properties of alpha-lactalbumin was studied in a pH range of 3.0 to 9.0. The range of HHP processes produced a variety of molten globules with differences in their surface hydrophobicity and secondary and tertiary structures. At pH values of 3 and 5, there was a decrease in the alpha-helix content concomitant with an increase in beta-strand content as the pressure increased. No changes in molecular size due to HHP-induced aggregation were detected by sodium dodecyl sulfate-PAGE. All samples showed higher thermostability as the severity of the treatment increased, indicating the formation of a less labile structure related to the HHP treatment.

Nanoparticles of bovine α-lactalbumin (α-LA) prepared by desolvation and glutaraldehyde crosslinking are promising carriers for bioactive compounds in foods. The objective of this work was to study the effect of changes in hydrophobic interactions by using different desolvating agents (acetone, ethanol, or isopropanol) and the use of a heat or high-pressure treatment step before the desolvation process on the size, structure, and properties of α-LA nanoparticles. In all cases, a high average particle yield of 99.63% was obtained. Smaller sizes (152.3 nm) can be obtained with the use of acetone as the desolvating agent and without any pretreatment. This is the first time that α-LA nanoparticles in the size range of 100 to 200 nm have been obtained. These nanoparticles, with an isoelectric point of 3.61, are very stable at pH values >4.8, based on their ζ-potential, although their antioxidant activity is weak. The use of the desolvating agent with the smallest polarity index (isopropanol) produced the largest particles (293.4 to 324.9 nm) in all cases. These results support the idea that controlling hydrophobic interactions is a means to control the size of α-LA nanoparticles. No effect of pretreatment on nanoparticle size could be detected. All types of nanoparticles were easily degraded by the proteolytic enzymes assayed.

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It is expected that ITC will continue to be utilized as a means of providing fundamental information about complex materials such as those found in foods. This knowledge may be used to create functional foods designed to behave in the gastrointestinal tract in a manner that will improve human health and well-being.