Sonication as a pre-processing step to alter acid whey generation during Greek yoghurt manufacture.

We investigated sonication as a pre-processing step to reduce acid whey generation during Greek yoghurt manufacture. The generation of a large amount of acid whey during the production of Greek yoghurt is an ongoing problem in the dairy industry and many studies are currently focusing on reducing it. We focused on the use of ultrasonication as a novel approach to minimize the casein fraction in the acid whey stream and simultaneously improve the gel properties. Ultrasound applied before the fermentation modified the structural properties and bonding behaviours of milk proteins, and enhanced the retention of casein in the yoghurt gel after the fermentation and straining steps. Therefore, the use of low-frequency ultrasonication as a pre-processing step may have the potential to provide significant economic benefits to the Greek yoghurt manufacturing process. Moreover, it improved the nutritional and physicochemical properties compared to regular Greek yoghurts.

Encapsulation of Nutraceuticals in Yoghurt and Beverage Products Using the Ultrasound and High-Pressure Processing Technologies.

Dairy and beverage products are considered highly nutritious. The increase demand for added nutritional benefits within the food systems consumed by the consumers paves the pathway towards fortifying nutraceuticals into these products. However, nutraceuticals are highly unstable towards harsh processing conditions. In addition, the safety of dairy and beverage products plays a very important role. Therefore, various heat treatments are in practice. As the heat-treated dairy and beverage products tends to illustrate several alterations in their organoleptic characteristics and nutritional properties, the demand for alternative non-thermal processing technologies has increased extensively within the food industry. Ultrasound and high-pressure processing technologies are desirable for this purpose as well as a safe and non-destructive technology towards encapsulation of nutraceuticals into food systems. There are benefits in implementing these two technologies in the production of dairy and beverage products with encapsulants, such as manufacturing high-quality products with improved nutritional value while simultaneously enhancing the sensory characteristics such as flavour, taste, texture, and colour and attaining the microbial quality. The primary objective of this review is to provide detailed information on the encapsulation of nutraceuticals and mechanisms involved with using US and HPP technologies on producing encapsulated yoghurt and beverage products.

Interfacial and emulsification properties of sono-emulsified grape seed oil emulsions stabilized with milk proteins.

Emulsions were designed under low frequency ultrasound (20 kHz) at energy densities of 11.7-117.0 J/mL using grape seed oil and milk protein solutions containing different casein to whey protein ratios of 80:20, 60:40, 50:50 and 40:60. An increase in energy densities produced emulsions with a smaller droplet size and narrow size distribution at all milk protein ratios. However, the minimum sono-energy density required to produce stable emulsions varied depending on the ratio of caseins (CN) and whey proteins (WP) in the continuous phase. In addition, the composition of the interfacial layer was dependent on the composition of the milk proteins in the continuous phase. The interfacial layer was predominantly covered by the CN and CN-WP aggregates in the presence of equal or greater amounts of caseins than whey proteins (80:20, 60:40 and 50:50), while WP aggregates and CN-WP aggregates were the primary constituents of whey protein-rich emulsions (40:60).

Influence of low-frequency ultrasound on the physico-chemical and structural characteristics of milk systems with varying casein to whey protein ratios.

Casein and whey proteins respond differently to ultrasound treatment depending on the individual protein fraction and the delivered energy density. The main aim of this study was to determine the sonication-induced physiochemical and structural changes of protein solutions with varying casein to whey protein ratios as a function of processing time at 20 kHz ultrasound. Four different casein:whey protein ratios (80:20, 60:40, 50:50, 40:60) were prepared. Upon sonication, there was a reduction in particle size of the 80:20 and 60:40 ratios, but the particle size of 50:50 and 40:60 increased. Milk protein solutions with higher portion of caseins produced more hydrophobically driven aggregates while whey protein-rich milk protein solutions produced more disulphide mediated aggregates during sonication. Primarily, ß-lactoglobulin was involved in the hydrophobic aggregation process and ß-lactoglobulin, bovine serum albumin and κ-casein participated in the disulphide aggregation process at all ratios.