Mechanism for Inhibition of Folic Acid Photodecomposition by Various Antioxidants.

Folic acid, a synthetic form of folate, is a water-soluble vitamin that is essential during periods of rapid cell division and growth. However, it decomposes upon ultraviolet irradiation to form inactive photoproducts. In this study, the protective effect and mechanisms of antioxidants, including cinnamic acids, flavonoids, catechol and its derivatives, stilbenes, p-benzoquinone and its derivatives, isoprenoids, curcumin, oleic acid, and linoleic acid, against folic acid photodecomposition were investigated by using fluorescence and absorbance spectroscopy, high-performance liquid chromatography, and antioxidant assay. It was found that antioxidants could inhibit or delay the folic acid decomposition in varying degrees, among which caffeic acid was the most effective. The increase in its remarkable antioxidant efficiency and absorbance in the UVA region during irradiation contributed to its effective protection. This finding could be useful for the protection of photolabile components in food and other uses.

Effects of Chinese pickled and dried mustard on nutritional quality, sensory quality, and shelf life of steamed pork belly.

Steamed pork with pickled and dried mustard (PDM) is a famous Chinese dish. Here, we examined the effects of PDM on nutritional quality, sensory quality, and shelf life of steamed pork belly. Proximate composition, lipid oxidation, fatty acid profiles, protein hydrolysis and oxidation, sensory evaluation, and induction period (IP) of steamed pork belly were determined after addition of different levels (0-100%, WPDM/Wpork belly) of PDM. The results demonstrated that PDM could significantly (p < .05) enhance the loss of moisture and fat, increase the ratio of unsaturated to saturated fatty acids, and decrease lipid and protein oxidation in steamed pork belly. Additionally, IP values and steamed pork belly preservation times increased as the amount of added PDM increased. Best sensory quality was achieved when moderate levels of PDM (40%) were added to steamed pork belly. These findings provide insights into the beneficial effects of PDM on steamed pork belly.

Protein oxidation and proteolysis during roasting and in vitro digestion of fish (Acipenser gueldenstaedtii).

BACKGROUND: Roasted fish enjoys great popularity in Asia, but how roasting and subsequent digestion influence the oxidation and proteolysis of fish meat is unknown. This study aimed to investigate the effect of roasting time on lipid and protein oxidation and their evolution and consequence on proteolysis during simulated digestion of fish fillets. RESULTS: Several oxidation markers (thiobarbituric acid-reactive substances (TBARS), free thiols, total carbonyls and Schiff bases) were employed to assess the oxidation of fish. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and the 2,4,6-trinitrobenzenesulfonic acid (TNBS) assay for free amino groups were used to study the proteolysis during gastrointestinal digestion. The results showed that significant lipid and protein oxidative changes occurring in roasted fish fillets were reinforced after gastric digestion and were much more intense after intestinal digestion. Throughout roasting and digestion, a close interconnection between lipid and protein was also manifested as the levels of total carbonyls and Schiff bases rose while TBARS fell. Furthermore, free amino groups decreased with prolonged roasting time, signifying that protein oxidation before digestion resulted in impaired proteolysis during digestion. CONCLUSION: This study indicated that the lipid and protein oxidation of fish fillets could be dependent on time of roasting, and the oxidation continued to develop and have an impact on proteolysis during in vitro digestion. © 2018 Society of Chemical Industry.

Protection of resveratrol against the photodecomposition of folic acid and photodecomposition-induced structural change of beta-lactoglobulin.

Folic acid is a synthetic form of the B-group vitamin known as folate and essential for a variety of physiological processes. However, it decomposes under UV irradiation, causing indirect oxidation and structural change of protein. In this study, the protective effect of resveratrol against the photodecomposition of folic acid and its caused protein structural change was investigated by using fluorescence and absorbance spectroscopy, high performance liquid chromatography and ABTS assay. It was found that resveratrol could inhibit the folic acid decomposition and control the decomposition process, depending on the polyphenol concentration and addition time. Transformation of resveratrol was accelerated by photodecomposition of folic acid. Antioxidant activity of resveratrol was important for the protective effect. Moreover, resveratrol could also inhibit the unfolding of beta-lactoglobulin caused by the folic acid decomposition by using circular dichroism.