Jonas T. Guimarães

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.

Physicochemical changes and microbial inactivation after high-intensity ultrasound processing of prebiotic whey beverage applying different ultrasonic power levels

In this work, we investigated the effects of the ultrasonic power (0, 200, 400 and 600 W) on non-thermal processing of an inulin-enriched whey beverage. We studied the effects of high-intensity ultrasound (HIUS) on microbial inactivation (aerobic mesophilic heterotrophic bacteria (AMHB), total and thermotolerant coliforms and yeasts and molds), zeta potential, microstructure (optical microscopy, particle size distribution), rheology, kinetic stability and color. The non-thermal processing applying 600 W of ultrasonic power was comparable to high-temperature short-time (HTST) treatment (75 °C for 15 s) concerning the inactivation of AMHB and yeasts and molds (2 vs 2 log and 0.2 vs 0.4 log, respectively), although HIUS has reached a lower output temperature (53 ± 3 °C). The HIUS was better than HTST to improve beverage kinetic stability, avoiding phase separation, which was mainly attributed to the decrease of particles size, denaturation of whey proteins and gelation of polysaccharides (inulin and gellan gum). Thus, non-thermal processing by HIUS seems to be an interesting technology for prebiotic dairy beverages production.

Ultrasound processing of fresh and frozen semi-skimmed sheep milk and its effects on microbiological and physical-chemical quality

The objective of this study was to evaluate the effect of ultrasound treatment on the microbiological quality, protein and free amino acid profile of fresh and frozen stored semi-skimmed sheep milk. Milk was treated as fresh or frozen and stored up to one, three and six months. Output power time and pulse time were the parameters combined to design four different ultrasound (US) treatments: power 78 W and duration 6 min (US1); power 78 W and duration 8 min (US2); power 104 W and duration 4 min (US3) power 104 W and duration 6 min (US4). Pulse duration was of 4 s for each treatment. Sample US1 was discarded due to non effectiveness of US treatment, while other samples showed interesting results. Also, it was verified a frost effect on microorganisms in all samples which were frozen before treatment. No relevant change was reported on amino acid profile. The study showed promising results: the ultrasound treatment inactivated or eliminated the studied contaminant bacteria in semi-skimmed sheep milk, while maintained acceptable amount of lactic bacteria, which could be advantageous for dairy products processing.

Yogurt and whey beverages available in Brazilian market: Mineral and trace contents, daily intake and statistical differentiation

Mineral and trace elements (Ca, Fe, K, Mg, Na, Pb, Cd, Cr, Cu, and Mn) in commercial strawberry-flavored yogurts and fermented whey beverages in Brazil were investigated. K, Ca, Na, Mg and Fe concentrations ranged from 1.6 to 1.4, 1.4 to 1.1, 0.74 to 0.68, 0.16 to 0.11, and 0.01 mg g-1 for yogurts and whey beverages, respectively. Similar concentrations of the minerals were observed for both products, except Mg (0.16 mg g-1 in yogurts and 0.11 mg g-1 in whey beverages). Cd, Cr, Cu, Mn, and Pb was found below the detection limit (21.4 to 94.1 μg g-1), demonstrating safety levels for consumption. Regarding the mineral daily intake, consumption of 100 g of the product has relevance for calcium in infants (>40%) and children between 4 and 8 years (>13%), and a greater contribution of yogurt over whey beverage was observed. PLSDA model suggested that Mg analytical determination should be performed to ensure the identity of the product.