Influence of yeast growth conditions and proteolytic enzymes on the amino acid profiles of yeast hydrolysates: Implications for taste and nutrition.

This study investigated the effects of aerobic and anaerobic growth and proteolytic enzymes on the amino acid content of yeast hydrolysates in relation to taste and nutrition. Saccharomyces cerevisiae ATCC5574 was grown under fed-batch aerobic or batch anaerobic conditions. Intracellular glutamic acid (Glu) concentrations were 18-fold higher in aerobic yeast. Hydrolysis with papain and alkaline protease released more amino acids (AA) than simple autolysis or hydrolysis with bromelain, most significantly when applied to aerobic yeast (∼2-fold increase). Autolysates and bromelain hydrolysates from aerobic yeast had low levels of bitter and essential AAs, with high levels of umami Glu. Papain and alkaline protease hydrolysates of aerobic yeast had high levels of umami, bitter and essential AAs. Autolysates/hydrolysates from anaerobic yeast had moderate, high, and low levels of bitter, essential and umami AAs. Selection of both yeast growth conditions and hydrolysis enzyme can manipulate the free AA profile and yield of hydrolysates.

Efficacy of flavonoids on biomarkers of type 2 diabetes mellitus: a systematic review and meta-analysis of randomized controlled trials.

A systematic review and meta-analysis of 28 randomized controlled trials (RCTs) to assess the efficacy of flavonoids intake on key biomarkers related to Type 2 diabetes mellitus was conducted. The mean difference (MD) with 95% confidence intervals (95% CI) was pooled using a random-effects model. Significant reduction in fasting glucose (MD: -0.22, 95% CI: -0.34 to -0.09, p = 0.0013), hemoglobin A1c (HbA1c) (MD: -0.26, 95% CI: -0.46 to -0.05, p = 0.021), homeostasis model assessment of insulin resistance (HOMA-IR) (MD: -0.40, 95% CI: -0.66 to -0.15, p = 0.0039), triglyceride (TG) (MD: -0.13, 95% CI: -0.21 to -0.05, p = 0.002), total cholesterol (TC) (MD: -0.14, 95% CI: -0.21 to -0.08, p = 0.0002), and low density lipoprotein-C (LDL-C) (MD: -0.15; 95% CI: -0.24 to -0.07, p = 0.0009) were observed in intervention group compare to placebo at the end of trial. Moreover, flavonoid intake had negative but non-significant effect on insulin (MD: -0.46), 2 h-postprandial glucose (2 h-PPG) (MD: -0.22), homeostasis model assessment of ß-cell function (HOMA-ß) (MD: -2.81), and insignificantly increased high-density lipoprotein-C (HDL-C) (MD: 0.03). In conclusion, flavonoid intake has modest but statistically significant benefits in glucose metabolism, insulin sensitivity, and lipid metabolism, especially for significantly lowing fasting blood glucose, HOMA-IR, HbA1c, TG, TC, and LDL-C.

The effectiveness of dietary polyphenols in obesity management: A systematic review and meta-analysis of human clinical trials.

Dietary polyphenols have been postulated to be effective in preventing obesity through various multitargeted mechanisms of weight loss. A meta-analysis of recent clinical trials was carried out to evaluate the effectiveness of polyphenols in obesity management in adults through assessing obesity-related anthropometric measures. Forty-four articles with 40 randomised clinical trials published between 2010 and 2021 met the eligibility trial criteria. Pooled results showed that polyphenols had a statistically significant reduction in body weight, body mass index and waist circumference. No significant lowering effect on body fat percentage was reported. Subgroup analysis suggested that polyphenol intake significantly changed anthropometric parameters in subjects aged <50 years, in Asian populations, in patients with obesity-related health issues, for periods of ≥ 3 months, and at dosages of <220 mg d-1. Overall, dietary polyphenols show promise in the prevention and management of obesity for certain adults.

Phytochemical profile of differently processed tea: A review.

Fresh tea leaves (Camellia sinensis (L.) O. Kuntze) are processed by various techniques to produce different types of tea. The most common way to classify tea types is based on the similarities in processing methods resulting in the five commonly recognized tea types: white, green, oolong, black, and pu-erh teas. The differences in the degree and nature of fermentation of tea leaves lead to different chemical changes depending on the processing method. Understanding the phytochemical profile of differently processed tea is important, as tea types classified by processing methods are currently not well defined because the chemical parameters for these tea types are still not established. Therefore, any significant characteristics found for a tea type due to processing may be helpful in defining tea types. However, the evidence on the impact of tea processing on phytochemical profile and contents in differently processed tea is currently unclear. Therefore, this review aims to examine (1) the processing techniques of white, green, oolong, black, and pu-erh tea, (2) the impact of tea processing on tea phytochemicals, and (3) the key characteristics associated with the phytochemical profiles of differently processed tea. PRACTICAL APPLICATION: Tea (Camellia sinensis (L.) O. Kuntz) is the most widely consumed beverage in the world. Tea consumption has been demonstrated through in-vitro experiments and in animal and human intervention studies to exhibit potential in preventing various oxidative stress-related chronic diseases, such as cardiovascular diseases, Alzheimer.s disease, diabetes and certain cancers. Based on the processing methods, tea is commonly categorized into white, green, oolong, black and pu-er tea. However, there are large overlap in processing methods between some teas and, more importantly, the chemical compositions of differently processed teas are highly variable. This review aims to examine (1) how white, green, oolong, black and Pu-erh tea are processed, (2) what are the effects of tea processing on tea phytochemicals and (3) to identify whether there are key characteristics associated to the phytochemical profiles of differently processed teas. The review will contribute to tea research in collating in one article the state of knowledge on the chemical changes and composition of the differently processed teas, and point to future direction in this area of research.

Beta-glucosidase activity of wine yeasts and its impacts on wine volatiles and phenolics: A mini-review.

Beta-glucosidase is an important enzyme for the hydrolysis of grape glycosides in the course of winemaking. Yeasts are the main producers of ß-glucosidase in winemaking, therefore play an important role in determining wine aroma and flavour. This article discusses common methods for ß-glucosidase evaluation, the ß-glucosidase activity of different Saccharomyces and non- Saccharomyces yeasts and the influences of winemaking conditions, such as glucose and ethanol concentration, low pH environment, fermentation temperature and SO2 level, on their activity. This review further highlights the roles of ß-glucosidase in promoting the release of free volatile compounds especially terpenes and the modification of wine phenolic composition during the winemaking process. Furthermore, this review proposes future research direction in this area and guides wine professionals in yeast selection to improve wine quality.

Characterization of Date (Deglet Nour) Seed Free and Bound Polyphenols by High-Performance Liquid Chromatography-Mass Spectrometry.

Date (Pheonix dactylifera L.) seeds are a valuable and abundant by-product with various potential food applications. Free polyphenols (FPPs) and bound polyphenols (BPPs) of date seeds from Deglet Nour variety grown in Australia were investigated using high-performance liquid chromatography-mass spectrometry. The FPP fraction contained the following main phenolic compounds per gram of date seed powder; procyanidin B1 (499.8 ± 7.8 µg), procyanidin B2 (288.6 ± 6.1 µg), catechin (167.6 ± 2.1 µg), epicatechin (39.44 ± 0.39 µg), and protocatechuic acid (1.77 ± 0.22 µg). Additionally, one of the 2 A-type dimers was confirmed as procyanidin A2 (24.05 ± 0.12 µg/g). A-type dimers have not been reported before in date seeds. The BPP fraction contained epicatechin (52.59 ± 0.76 µg/g) and procyanidin B2 (294.2 ± 3.7 µg/g), while several peaks exhibiting ESI- m/z of 153 indicated dihydroxybenzoic acid isomers including protocatechuic acid (2.138 ± 0.025 µg/g). These findings contributed to our knowledge of date seed phytochemicals and understanding of their contribution to the reported bioactivities.