Effects of microwave heating on the chemical composition and bioactivity of orange juice-milk beverages.

The effect of microwave heating (MH, 65 and 75 °C for 15, 30, and 60 s) on the bioactive compounds, fatty acid profile, and volatile compounds of orange juice-milk beverage (OJMB) was evaluated during 28 days of refrigerated (4 °C) storage. Conventionally pasteurized (75 °C/15 s) and untreated beverages were used as controls. MH-OJMB presented a lower browning index and higher levels of ascorbic acid, total phenolics, and carotenoids, higher antioxidant activity, and greater α-amylase, α-glucosidase, and ACE inhibitory activity than the pasteurized product, similar to the untreated beverage. No significant differences were observed in the volatile organic compounds and fatty acids levels. Lower temperatures (65 °C) and longer process times (60 s) resulted in higher retention of bioactive compounds. MH can be an alternative to conventional pasteurization for OJMB processing.

Microwave Processing: Current Background and Effects on the Physicochemical and Microbiological Aspects of Dairy Products.

Overheating is still a major problem in the use of conventional heating for milk and various dairy products, because it leads to the lowering of quality and sensory and nutritional values. Microwave (MW) heating has been credited with providing superior-quality dairy-based products with extended shelf-life, representing a good alternative to conventional heat treatment. The main drawback of MW heating refers to nonuniform temperature distribution, resulting in hot and cold spots mainly in solid and semisolid products; however, MW heating has been shown to be suitable for liquid foods, especially in a continuous fluid system. This review aims to describe the main factors and parameters necessary for the application of MW heating technology for dairy processing, considering the theoretical fundamentals and its effects on quality and safety aspects of milk and dairy products. MW heating has demonstrated great ability for the destruction of pathogenic/spoilage microorganisms and their spores, and also inactivation of enzymes, thereby preserving fresh characteristics of dairy products.

Chemical, sensory, and functional properties of whey-based popsicles manufactured with watermelon juice concentrated at different temperatures.

The effects of the concentration of watermelon juice at different temperatures (45, 55, or 65 °C) on the physicochemical and sensory characteristics, antioxidant capacity, and volatile organic compounds (VOCs) of whey-based popsicles were investigated. Total phenolic content, lycopene, citrulline, VOCs, melting rate, instrumental colour, antioxidant capacity, and the sensory characteristics (hedonic test and free listing) were determined. The temperature led to a significant decrease in bioactive compounds (total phenolics, lycopene, and citrulline). The popsicle manufactured with reconstituted watermelon juice concentrated to 60 °Brix at 65 °C presented higher antioxidant capacity and was characterized by the presence of alcohols, aldehydes and ketones and presented a similar acceptance to the untreated popsicle (except for flavour). It is possible to combine whey and concentrated watermelon juice for the manufacture of bioactive-rich popsicles, using the concentration temperature of 65 °C as a suitable processing condition for potential industrial applications.

Whey-grape juice drink processed by supercritical carbon dioxide technology: Physicochemical characteristics, bioactive compounds and volatile profile.

The effect of supercritical carbon dioxide technology (SCCD, 14, 16, and 18MPa at 35±2°C for 10min) on whey-grape juice drink characteristics was investigated. Physicochemical characterization (pH, titratable acidity, total soluble solids), bioactive compounds (phenolic compounds, anthocyanin, DPPH and ACE activity) and the volatile compounds were performed. Absence of differences were found among treatments for pH, titratable acidity, soluble solids, total anthocyanin and DPPH activity (p-value>0.05). A direct relationship between SCCD pressure and ACE inhibitory activity was observed, with 34.63, 38.75, and 44.31% (14, 16, and 18MPa, respectively). Regards the volatile compounds, it was noted few differences except by the presence of ketones. The findings confirm the SCCD processing as a potential promising technology to the conventional thermal treatment.