Ultrasound-assisted enzymatic hydrolysis of goat milk casein: Effects on hydrolysis kinetics and on the solubility and antioxidant activity of hydrolysates.

This study evaluated the ability of ultrasound (US) bath to improve the hydrolysis of goat milk casein (GMC) by three commercial proteases (Alcalase, Brauzyn and Flavourzyme) using assisted reactions at 60 °C for up to 300 min. Process performance was evaluated based on the rate reaction, final hydrolysis degree, solubility, and antioxidant activity of the hydrolysates. For all enzymes, the US-assisted reaction increased the rate of GMC hydrolysis (up to 120%), the hydrolysis degree (23-48%), and the small peptides formed, i.e., those soluble in trichloroacetic acid (TCA) (up to 40%). Consequently, US-assisted GMC hydrolysis improved the solubility of the hydrolyzed product (up to a 35.7% increase after 300 min of reaction) and, compared to conventional hydrolysis, reduced the time to achieve the maximum solubility by up to 10 times. Regarding the in vitro antioxidant activity, especially for Alcalase, the technology promoted a higher scavenging capacity of 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) (p < 0.05), thus 10-fold accelerating the production of antioxidant peptides, according to ABTS assays (p < 0.05). In conclusion, the US-assisted enzymatic reaction is a promising technology to improve the hydrolysis rate and yield of the process of obtaining hydrolysates from GMC. Moreover, these hydrolysates showed high solubility and good in vitro antioxidant activity, which demonstrates the potential to be used as food ingredient with nutritional and techno-functional appeal.

Influence of Homogenization in the Physicochemical Quality of Human Milk and Fat Retention in Gastric Tubes.

BACKGROUND: The retention of human milk nutrients in gastric tubes used to feed premature infants is a challenge to be overcome. RESEARCH AIMS: To evaluate (1) the performance of six homogenizers (mixing processor, piston valve, ultrasonic bath, ultraturrax, stirring mixer, and ultrasound probe) for the fat retention reduction in gastric tubes; (2) the influence of the best homogenization conditions on the fatty acid and protein profiles of human milk; and (3) the cost/benefit ratio for the inclusion of homogenization as a new step in human milk processing. METHODS: The influence of different levels and times of homogenization on reducing fat retention of human milk in probes was evaluated in this comparative prospective cross-sectional study. After homogenization, human milk flowed through a gavage and infusion pump apparatus used for feeding. Fat content was quantified before and after feeding. The techniques that reduced fat globule sizes and/or promoted a lower percentage of fat holding were evaluated for efficiency, variations in the fatty acid and protein profiles, and energy density and operating costs. RESULTS: Homogenization led to a reduction in fat retention in feeding probes. The mixer processor and the ultrasound probe reduced fat retention by 99.23% (SD = 0.07) and 99.95% (SD = 0.02), respectively, and did not negatively influence fatty acid and protein profiles. The mixer processor demonstrated low energy density and low cost for human milk processing. CONCLUSION: Homogenization promoted reduced fat retention in the feed probe and could help maintain fat nutrients of human milk during enteral feeding.

Nanostructured conjugates from tara gum and α-lactalbumin. Part 1. Structural characterization.

Nanostructures from conjugates of tara gum and α-lactalbumin were obtained via the heat-gelation process with pH adjustment. The conjugates were produced by Maillard reaction using the dry-heating method in lyophilized or spray-dried mixtures of TG and α-la and were characterized by browning index (BI) and percentage of free amino groups (% FAG). Nanostructured systems were characterized by dynamic light scattering, ζ-potential, circular dichroism, and intrinsic fluorescence to evaluate the structures. The most appropriate time of conjugation was 2 days. The spray-dried and lyophilized mixtures presented different values of BI and % FAG (p < 0.05), indicating that the glycosylation was more intense in lyophilized mixtures. Nanostructures with average sizes lower than 300 nm were formed under different conditions of temperature, pH, and heating time. Analyses of circular dichroism and intrinsic fluorescence showed conformational changes in the nanostructures, mainly a decrease in the α-helix content in spray-dried systems. The characteristics presented by the studied systems showed that it is possible to obtain nanostructures from conjugates of tara gum and α-lactalbumin.

Teor de vitamina C, β-caroteno e minerais em camu-camu cultivado em diferentes ambientes / Levels of vitamin C, β-carotene and minerals in camu-camu cultivated in different environments

RESUMO: O objetivo deste trabalho foi avaliar a influência do tipo de cultivo (ambiente seco e alagado) sobre o teor de vitamina C, β-caroteno e minerais (cálcio, magnésio, enxofre, zinco, ferro, manganês, cobre, boro, nitrogênio, fósforo e potássio) de camu-camu. As vitaminas citadas foram determinadas por cromatografia líquida de alta eficiência, enquanto que os minerais cálcio, magnésio, zinco, cobre, manganês e ferro por espectrometria de absorção atômica, o potássio por fotometria de chama e o fósforo, boro e enxofre por espectrofotometria, nos comprimentos de onda 725 e 420nm, respectivamente. O fruto cultivado em ambiente seco apresentou maior (P<0,05) teor de vitamina C (13.756,79mg 100g1/peso seco) e da maioria dos minerais investigados (cálcio, magnésio, enxofre, ferro, cobre, nitrogênio, fósforo e potássio). Os teores de β-caroteno não variaram (P>0,05) em função dos diferentes ambientes.

ABSTRACT: The aim of this study was to evaluate the influence of crop type (dry and flooded environment) on vitamin C, β-carotene and minerals (calcium, magnesium, sulfur, zinc, iron, manganese, copper, boron, nitrogen, phosphorus and potassium), of camu-camu content. Vitamins were determined by high performance liquid chromatography, calcium, magnesium, zinc, copper, manganese and iron by atomic absorption spectrometry, potassium by flame photometry and phosphorous, boron and sulfur by spectrophotometry in wave lengths 725 and 420nm, respectively. Fruit grown in a dry environment showed higher (P<0.05) vitamin C content (13756.79mg 100g-1/dry weight) and generally higher mineral content (calcium, magnesium, sulfur, iron, copper, nitrogen, phosphorus and potassium). β-carotene content was not influenced (P>0.05) by different environments.