Heat stability of radio frequency dielectric heat treated low heat and high heat nonfat dry milk

Impact of cold plasma on the techno-functional and sensory properties of whey dairy beverage added with xylooligosaccharide

This study aimed to evaluate the impact of cold plasma (0, 5, 10, or 15 min) on the techno-functional and sensory properties of whey dairy beverages added with xylooligosaccharide (XOS, 1.5% p/v). Untreated and pasteurized whey beverages were also evaluated. The products were evaluated for physicochemical characteristics, bioactive compounds, XOS stability, rheological properties, and sensory characteristics. Cold plasma and pasteurized products presented lower color intensity (L*=87.4-87.9, a*=-0.24- -0.60, b*=2.41-5.19), reduced consistency (K = 4.31-42.21 mPa.sⁿ and N = 0.57-0.95), and similar apparent viscosity, XOS chemical stability, and sensory characteristics compared with the untreated product. However, the cold plasma-treated beverages presented lower heat load indicators (hydroxymethylfurfural [HMF] values of 1.91-2.10 µmol/L and whey protein nitrogen index [WPNI] of 6.09-6.66 µmol/L) and a higher concentration of bioactive compounds (antioxidant activity [5.31-9.30%], and inhibition of ACE [14.17-22.53%], α-amylase [18.52-25.67%] and α-glucosidase [22.50-27.50%] activities) than the pasteurized product, being the effects more pronounced for the higher exposure times. Overall, cold plasma has important advantages for the processing of whey beverages added with XOS.

Process development for a novel milk protein concentrate with whey proteins as fibrils

Milk protein concentrate (MPC) is a preferred ingredient to provide nutritional and functional benefits in various dairy and food products. Altering the protein configuration and protein-protein interactions in MPC can provide a novel functionality and may open doors for new applications. The fibrilization process converts the globular structure of whey proteins to fibrils and consequently increases viscosity and water holding capacity compared with the native protein structure. The objective of the current work was to selectively convert the whey proteins in MPC as fibrils. For this purpose, simulated control model MPC was prepared by combining solutions of micellar casein concentrate (MCC) and milk whey protein isolate (mWPI) to give casein and whey protein in an 80:20 ratio. The mWPI solution was converted to fibrils by heating at low pH, neutralized, and combined with MCC solution similar to control model MPC and termed "fibrillated model MPC." Thioflavin T fluorescence value, transmission electron microscopy, and gel electrophoresis confirmed the fibril formation and their survival after neutralization and mixing with MCC. Further, the fibrillated mWPI showed significantly higher viscosity and consistency coefficient than nonfibrillated mWPI. Similarly, fibrillated model MPC showed significantly higher viscosity and consistency coefficient compared with control model MPC. Hence, the fibrillated model MPC can be used as ingredient to increase viscosity. Heat coagulation time was found to be significantly higher for control model MPC compared with fibrillated model MPC.

Application of a dry heat treatment to enhance the functionality of low-heat nonfat dry milk

Nonfat dry milk is a valuable food and ingredient because it contains proteins, fat, carbohydrates, minerals, and vitamins. When manufactured, this product is classified into high heat (HH) or low heat (LH) depending on the pre-heat treatment used in pasteurization. Radio frequency dielectric heating, if used alone or as part of a dry heat technology, may induce component interactions in milk powders, which could alter or improve functionality. To pursue this objective, LH was subjected to radio frequency dielectric heating to 80, 85, and 90°C with a subsequent hold period of 60 or 90 min in an oven, set at the designated temperature, 80, 85, or 90°C, assessed for functionality in liquid and gel systems, cooled, and subsequently compared with LH and HH. The functionality assessment included heat stability and foaming, emulsion, and gelling properties. For foaming, LH presented a statistically lower overrun and foam stability compared with all dry-heated LH. The LH dry-heated at ≥85°C exhibited significantly greater foaming capacity than did the LH. Emulsification properties were not significantly different as a function of dry heating compared with LH. As gels, water-holding capacity was greater and syneresis was significantly less for all gels made with the dry-heated LH at <85°C. Gel firmness and cohesiveness were not affected by dry heating. The heat coagulation time at native pH was significantly greater for LH that were dry-heated for 90 min compared with LH. At adjusted pH (6.4 to 7.2), the heat stability was improved if the LH was dry-heated. The dry-heated LH had significantly less foaming properties, but greater emulsion activity compared with the HH. Overall, the dry heat treatment conditions of this study did not result in acid-induced gels with equivalent properties as gels made with HH. Syneresis was similar for all gels except for those made from the dry-heated LH to 90°C and held for 60 min, as this gel had significantly more syneresis than did the gels made from HH. However, the heat stability of dry-heated LH at native, 6.8, 7.0, and 7.2 pH was greater compared with the heat stability of HH. The application of a dry heat treatment enhanced the functional properties of LH, opening the opportunity to develop food products that can use this modified nonfat dry milk such as ice cream, bakery, and meat products.