Characterisation of volatile compounds of farmed soft‐shelled turtle (Pelodiscus sinensis) by solid‐phase microextraction and the influence of matrix pH on the release of volatiles

Although farming and consuming of soft‐shelled turtle has been practised for centuries, the aroma‐impact compounds in the meat have not been determined. Furthermore, matrix pH, usually changing during processing and storage stage, was rarely investigated for the influence on volatile profiles. To these aims, soft‐shelled turtle meat was subjected to different pH conditions and the potential volatile compounds were analysed under different extraction conditions by headspace solid‐phase microextraction (HS‐SPME). A total of forty‐three volatiles were identified; in which, nonanal, (E, E)‐2, 4‐heptadienal, octanal, decanal, hexanal, (E)‐2‐nonenal, heptanal, 1‐octen‐3‐ol and o‐xylene were assigned as aroma‐impact compounds by high relative odour activity value (ROAV). Overly basic or acidic pH significantly (P < 0.05) facilitated the release of volatiles under moderate extraction conditions. The total volatilisation increased by 30.1% to 298% in pH‐shifted samples, while the highest one was found in pH 2 or pH 11. However, the results of principal components analysis (PCA) demonstrated that increased extraction time or temperature hindered the pH enhancement.     

Green recovery of phenolic compounds from rice byproduct (rice bran) using glycerol based on viscosity,conductivity and density

Rice bran, the industry byproduct, contains high levels of phenolic compounds. Based on glycerol, a green recovery of phenolics from rice bran was proposed. Extraction temperature (X₁), glycerol concentration (X₂) and liquid-to-solid ratio (X₃) were optimised by response surface methodology. Basic physical properties, that is, viscosity, conductivity, density were analysed and UPLC-Triple-TOF/MS method was applied for phenolic identification. Results showed the optimum conditions were X₁ = 66.76 °C, X₂ = 19.47% and X₃ = 32.92 mL g⁻¹. Under these conditions, the recovery yield in total polyphenols was 708.58 ± 12.36 mg GAE/100 g DW. Moreover, the recovery capacity of phenolic compounds was significantly correlated with viscosity, conductivity and density of glycerol solution. Under the optimal conditions, totals of thirteen phenolic compounds were identified and phenolic acids (4-hydroxybenzoic acid, vanillic acid, syringic acid, 4-coumaric acid, ferulic acid and salicylic acid) were quantified. These results demonstrate glycerol can serve as an ideal green solvent to recover phenolic compounds from rice bran.     

Preparation and purification of angiotensin‐converting enzyme inhibitory peptides from hydrolysate of shrimp (Litopenaeus vannamei) shell waste

Angiotensin I‐converting enzyme (ACE) inhibitory peptides from the shrimp shell waste (SSW) were isolated using different proteases. The orthogonal test results showed alcalase hydrolysates with ACE inhibitory activity of 67.07% under the optimal hydrolysis conditions of 60 °C hydrolysis temperature, pH = 9.5, 25 g L^?1 substrate and 4000 U g^?1 of enzyme, whereas neutral protease hydrolysates had an ACE inhibitory activity of 84.04% under the hydrolysis temperature of 50 °C at pH = 7.0 with 25 g L^?1 of substrate and in the presence of 2000 U g^?1 of enzyme. Neutral protease was more suitable for the production of ACE inhibitory peptides from SSW, where peptides with MW <5 kDa were recommended. The results of this study indicated that peptides obtained from SSW are as beneficial as antihypertension compounds in the functional food resources.     

Antioxidant and tyrosinase inhibitory activity of Rosa roxburghii fruit and identification of main bioactive phytochemicals by UPLC‐Triple‐TOF/MS

The content of bioactive phytochemicals, antioxidant activity and tyrosinase inhibitory activity of the hydroalcoholic extracts of Rosa roxburghii were determined. Yellow fruits of cultivated R. roxburghii showed the highest phenolic content (154.81 mg gallic acid g^?1), and the green fruits of wild R. roxburghii showed higher content of flavonoid and triterpenoid. Rosa roxburghii fruits from different cultivars and maturity stages all demonstrated as good antioxidant agents and tyrosinase inhibitors, with IC50 value about twice of the positive standard in the DPPH assay and triple of the standard in the tyrosinase inhibitory activity assay. Nineteen compounds, mainly ellagic acids and its derivatives, flavonoids and their glycosides were identified by UPLC‐Triple‐TOF/MS analysis. As the first study of bioactive phytochemicals of R. roxburghii by UPLC‐MS, the present research may provide valuable information for fulfilling the potential of R. roxburghii in the functional food area.     

莲子皮渣中酚类物质的提取优化及抗氧化活性评价

本文以莲子加工副产物-莲子皮渣为实验材料,在单因素实验的基础上,以总酚、总原花色素、DPPH·+清除能力为响应值,通过响应面设计优化莲子皮渣活性成分超声辅助提取条件,建立二次响应面回归模型,模型均显著且拟合性好。最优提取工艺为:丙酮浓度70%,料液比1:25.5 g/mL,提取时间1.6 h,提取温度50℃。该提取条件下,里叶白莲莲子皮渣提取物总酚、总原花色素、DPPH·+清除能力分别为194.54±3.63 mg GAE/g DW,243.15±2.88 mg CE/g DW,238.53±3.07 mg AAE/g DW,与预测值相符,证明实验建立的响应面模型可用于莲子皮渣中总酚、总原花色素、DPPH·+清除能力实验结果预测。对不同品种莲子皮渣植物化学素含量及体外抗氧化活性进行测定,发现莲子皮渣均富含多酚、类黄酮、原花色素、三萜等生物活性物质,且具有较高体外抗氧化活性。研究表明莲子皮渣富含生物活性成分,具有开发利用的巨大潜在价值。     

Lotus Flavonoids and Phenolic Acids: Health Promotion and Safe Consumption Dosages

Nelumbo nucifera Gaertn., also known as the sacred lotus, is extensively cultivated in Southeast Asia, primarily for food and as an herbal medicine. This article reviews studies published between 1995 and 2017, on flavonoid and phenolic acid profiles and contents of 154 different cultivars of lotus. So far, some 12 phenolic acids and 89 to 90 flavonoids (47 flavonols, 25 to 26 flavons, 8 flavan‐3‐ols, 4 flavanons, and 5 anthocyanins) have been isolated from different parts of the lotus plant, including its leaves (whole leaf, leaf pulp, leaf vein, and leaf stalk), seeds (seedpod, epicarp, coat, kernel, and embryo), and flowers (stamen, petal, pistil, and stalk), although not all of them have been quantified. Factors affecting flavonoids and phenolic acid profiles, including types of tissues and extracting factors, are discussed in this review, in order to maximize the application of the lotus and its polyphenols in the food industry. Health promotion activities, attributed to the presence of flavonoids and phenolic acids, are described along with toxicology studies, illustrating appropriate usage and safe consumption dosages of lotus extracts. This review also presents the controversies and discusses the research gaps that limit our ability to obtain a thorough understanding of the bioactivities of lotus extracts.     

Effect of Micro-Perforated Film Packing on Fatty Acid-Derived Volatile Metabolism of “Red Globe” Table Grapes

The present study was aimed at understanding the effect of micro-perforated polyethylene film packing (MPFP) on the metabolism of fatty acid-derived volatiles and physicochemical attributes in “Red Globe” table grapes under storage at 0 °C for 50 days. Physicochemical properties evaluated in grapes were total soluble solids (TSS), texture profile, decay incidence, fatty acid content, and aroma-related enzyme activities including lipoxygenase (LOX), hydroperoxide lyase (HPL), alcohol dehydrogenase (ADH), and volatiles in grape peel and flesh. Aroma-related genes (VvLOX, VvHPL, and VvADH) were also evaluated. Grapes treated with MPFP was found to retain the texture profile and decay incidence was reduced (17.4% of reduction compared with control) significantly (P?≤?0.05). Linoleic acid (LA), the main substrate of LOX/HPL pathway, was the highest in table grapes packed in MPFP, indicating the use of MPFP was able to preserve LA compound. Micro-perforated film packing upregulated VvLOX and VvHPL, downregulated VvADH, increased LOX and HPL activities, and inhibited ADH activity, enhancing C6/C9 compounds. The results indicated that MPFP system was the best choice to improve aroma quality of “Red Globe” table grapes in comparison to polyethylene film packing (PFP) and control (no packing).     

Phytosterols and their derivatives: Potential health‐promoting uses against lipid metabolism and associated diseases,mechanism, and safety issues

Consumption of phytosterols (PSs), the plant‐based analogs of cholesterol, can reduce serum cholesterol levels. This review discusses the current state of the art into the research of the structural features and dietary sources of PSs and their derivatives. The effect of PSs on individual lipid metabolites is summarized in the present review. PS‐related nonalcoholic fatty liver disease (NAFLD), obesity, and the alleviation of inflammatory bowel diseases are discussed. PSs reduce the risk of having NAFLD by improving the blood biochemical parameters related to lipid transport and metabolism. However, current research on the circulating PSs indicates its safety concern regarding fatty liver disease induction. In addition, PS oxidation products exhibit pro‐atherogenic properties, cytotoxicity oxidative stress, apoptosis, and pro‐inflammatory properties. Further research is needed to investigate the bioavailability and safety issues of PSs and their derivatives in animal models and clinical trials.