Evaluation of microbial toxins,trace elements and sensory properties of a high-theabrownins instant Pu-erh tea produced using Aspergillus tubingensis via submerged fermentation

Theabrownins (TB) are polymeric phenolic compounds associated with the multiple bioactivities of Pu-erh tea, a post-fermented Chinese dark tea. High-TB instant Pu-erh tea was produced via a novel submerged fermentation (SF) using Aspergillus tubingensis and compared with samples produced commercially via the conventional solid-state fermentation (SSF). Viable microorganisms and microbial toxins, especially aflatoxins B₁, G₁, B₂, G₂, cyclopiazonic acid, fumonisins B₁, B₂, B₃ and ochratoxin A, were below the detection limit in all samples. Fewer microbial metabolites were found in SF instant tea compared with the SSF teas. Based on an adult consuming 1 g of instant Pu-erh tea daily, the dietary intake of investigated elements was below the safe limits recommended by various authorities. Tasters viewed the instant tea infusions as very mild, smooth, mellow and full. This suggested that submerged fermentation using A. tubingensis offers a speedy and safe alternative to commercial production of instant Pu-erh tea.     

Efficacy of low concentration neutralised electrolysed water and ultrasound combination for inactivating Escherichia coli ATCC 25922, Pichia pastoris GS115 and Aureobasidium pullulans 2012 on stainless steel coupons

The sanitising effect of low concentration neutralised electrolysed water (LCNEW, pH: 7.0, free available chlorine (FAC): 4 mg/L) combined with ultrasound (37 kHz, 80 W) on food contact surface was evaluated. Stainless steel coupon was chosen as attachment surface for Escherichia coli ATCC 25922, Pichia pastoris GS115 and Aureobasidium pullulans 2012, representing bacteria, yeast and mold, respectively. The results showed that although LCNEW itself could effectively reduce survival population of E. coli ATCC 25922, P. pastoris GS115 and low concentration A. pullulans 2012 in planktonic status, LCNEW combined with ultrasound showed more sanitising efficacy for air-dried cells on coupons, with swift drops: 2.2 and 3.1 log CFU/coupon reductions within 0.2 min for E. coli ATCC 25922 and P. pastoris GS115, respectively and 1.0 log CFU/coupon reductions within 0.1 min for A. pullulans 2012. Air-dried cells after treatment were studied by atomic force microscopy (AFM)/optical microscopy (OM) and protein leakage analyses further. All three strains showed visible cell damage after LCNEW and LCNEW combined with ultrasound treatment and 1.41 and 1.73 μg/mL of protein leakage were observed for E. coli ATCC 25922 and P. pastoris GS115, respectively after 3 min combination treatment, while 6.22 μg/mL of protein leakage for A. pullulans 2012 after 2 min combination treatment. For biofilms, LCNEW combined with ultrasound also significantly reduced the survival cells both on coupons and in suspension for all three strains. The results suggest that LCNEW combined with ultrasound is a promising approach to sanitise food equipment.     

基于代谢组学研究不同花色种类云南白茶的化学成分差异

以云白毫、白牡丹（包括月光白一级和月光白二级）、云寿为云南白茶的代表性样品,采用基于超高效液相色谱-四极杆轨道阱质谱的代谢组学方法对不同花色种类云南白茶的化学成分差异进行研究。共鉴定出120 个化合物,包括儿茶素类、二聚儿茶素类、氨基酸类、生物碱类、酚酸类、有机酸类、香气糖苷类、N-乙基-2-吡咯烷酮取代的儿茶素类、黄酮糖苷类、脂质类等。偏最小二乘法判别分析和热图分析分别表明不同花色种类云南白茶的化学成分存在较大差异,共得到76 个化合物具有组间显著性差异（P＜0.05）,其中儿茶素类、二聚儿茶素类、生物碱类、酚酸类、茶氨酸等化合物随云南白茶原料嫩度的降低,含量下降;部分氨基酸和杨梅素苷在白牡丹中含量相对较高;芹菜素苷、山柰酚苷、槲皮素苷、脂质类化合物在云寿中含量相对较高。本研究可为云南白茶感官品质和营养价值的研究以及等级判别提供理论依据。     

基于非靶向代谢组学方法探究德昂酸茶与普洱茶（熟茶）之间的成分差异

为了探究使用云南大叶种茶树制作不同种类的发酵茶德昂酸茶和普洱茶（熟茶）（以下简称“普洱熟茶”）之间的代谢产物差异,采用超高效液相色谱-四极杆飞行时间质谱技术,对德昂酸茶和普洱熟茶进行非靶向代谢组学研究。结果发现,德昂酸茶和普洱熟茶虽原料相同但因其加工方式不同,而存在较大的代谢物差异。通过主成分分析和正交偏最小二乘判别分析可以显著区分不同发酵工艺茶叶中的代谢产物,共检测出21 类268 种显著性差异代谢产物,占所有代谢物的63.81%,主要包括49 种氨基酸类、39 种脂肪酸、36 种核苷酸类、29 种有机酸、18 种糖类。其中,麦角硫因、3,4-二甲氧基苯乙酸、3-羟基扁桃酸、氯化乙酰胆碱、2-羟基-4-甲基戊酸、米格列醇、L-脯氨酸、4,6-二氧代庚酸、丙二醇、原花青素B2、N-乙酰甘氨酸等差异代谢产物对于不同发酵工艺的茶叶不同滋味品质的形成可能具有重要贡献。京都基因与基因组百科全书代谢通路分析发现,德昂酸茶和普洱熟茶的氨基酸和核苷酸类物质代谢水平具有显著差异,涉及氨基酸代谢和核苷酸类代谢相关的通路对不同发酵工艺茶叶的滋味品质有重要影响。该研究从植物代谢组学角度揭示德昂酸茶和普洱熟茶的代谢产物差异性。     

Comparison of simplex and duplex real-time PCR for the quantification of GMO in maize and soybean

This paper focuses on the determination of the GMO content of maize and soybean samples using real-time PCR, comparing simplex and duplex PCR. The total DNA content of samples was determined by amplifying part of a maize gene encoding a lipid transfer protein, or part of a soybean lectin gene. The transgenic DNA was quantified by amplifying part of the CaMV 35S promoter. The importance of preparation and conservation of standards as well as the relevance of DNA extraction protocol on the variability of results are discussed. For the determination of low GMO content, limitation in the number of copies of the target gene to be amplified is considered. For samples with a theoretical GMO content of 1%, corresponding to the legal threshold for labelling, the value determined by duplex real-time PCR ranged from 0.85% to 1.20%. Both real-time simplex and duplex PCRs allowed identification of GMO free samples without ambiguity.     

香茅草烤鸡翅的工艺优化及品质分析

目的以香茅草和新鲜鸡翅为主要原料,研制一种香茅草烤鸡新产品。方法采用单因素实验(腌制时间、腌制温度、香茅草添加量)和正交实验确定最佳工艺参数,并通过感官评定和质构仪(textureprofile analysis,TPA)指标,分析烤制温度及时间对香茅草烤鸡翅品质的影响。结果香茅草烤鸡翅的最佳腌制工艺为:腌制时间1.5 h,腌制温度10℃,香茅草添加量0.5 g。温度及时间对香茅草烤鸡翅的硬度、咀嚼性的影响,有显著性差异(P0.05),温度对弹性的影响,差异不显著(P0.05)。发现烤制温度为210℃,时间为22 min时,香茅草烤鸡翅的硬度、咀嚼性测定值最大。结论此工艺下得到的产品,色泽焦黄,鸡肉香味浓郁,柠檬味持久,可以为香茅草烤鸡翅的工艺研究提供一定的借鉴。     

Effect of preincubation of sorghum flour with enzymes on the digestibility of sorghum gruel

A low-tannin sorghum cultivar M-35-1 was used in this study. Sorghum was germinated for 6 days and protease and amylase activities were measured every 24 h. Results showed that the 5th day germinated sorghum had a higher protease activity and a lower amylase activity. Sorghum flour was incubated for 30 min with the extract from germinated sorghum or with 0.01, 0.05 or 0.1 mg ml⁻¹ papain or trypsin prior to cooking in water. Results showed increase in in vitro protein digestibility (IVPD) with the 5th day germination extract. Pretreatment of sorghum flour with small amounts of papain or trypsin (0.01 mg ml⁻¹) improved the IVPD without affecting the paste viscosity, whereas the germinated sorghum extract led to very low paste viscosity. ©     

甲基纤维素添加量对低盐肉糜凝胶特性的影响

将甲基纤维素(methyl cellulose,MC)作为替代物加入肉糜中等量替代食盐,采用5个不同MC添加量(0％、0.4％、0.8％、1.2％、1.6％)即肉糜中的食盐质量分数分别为2％、1.6％、1.2％、0.8％、0.4％.通过测定肉糜凝胶的蒸煮损失率、色泽、质构、低场核磁共振横向弛豫时间(T2)以及流变特性,...     

Pesticide residues in grapes and during vinification process

Pesticide residues in vinification process of two white and two red grapevine varieties were monitored during the 2007 vintage. Crushed grapes, cake, must, lees and wine were sampled during the vinification process. Additionally, grapes were sampled during the ripening process. All samples were taken in triplicate and analyzed for the presence of 117 pesticides. The pesticide residues were determined by three validated internal analytical methods: the multi-residual GC-MS method (71 pesticides), the multi-residual LC-MS-MS method (45 pesticides) and GC-MS method for the determination of dithiocarbamates (the sum of their concentrations is given as a concentration of carbon disulfide). Boscalid and phosalone were the most persistent pesticides in grapes during ripening. The concentrations of pesticide residues in must and wine were significantly diminished through separations during the solid and liquid phases of the vinification process, particularly the pressing of crushed grapes and wine racking after alcoholic fermentation. The pesticides detected throughout the vinification process were boscalid, cyprodinil, dimethomorph, fenhexamid, metalaxyl and procymidone and their concentrations in the wines were 0.01–0.02, 0.04, 0.01–0.08, 0.12–0.13, 0.09–0.11 and 0.07–0.13 mg L⁻¹ respectively.     

Reviewing the world's edible mushroom species: A new evidence-based classification system

Wild mushrooms are a vital source of income and nutrition for many poor communities and of value to recreational foragers. Literature relating to the edibility of mushroom species continues to expand, driven by an increasing demand for wild mushrooms, a wider interest in foraging, and the study of traditional foods. Although numerous case reports have been published on edible mushrooms, doubt and confusion persist regarding which species are safe and suitable to consume. Case reports often differ, and the evidence supporting the stated properties of mushrooms can be incomplete or ambiguous. The need for greater clarity on edible species is further underlined by increases in mushroom-related poisonings. We propose a system for categorizing mushroom species and assigning a final edibility status. Using this system, we reviewed 2,786 mushroom species from 99 countries, accessing 9,783 case reports, from over 1,100 sources. We identified 2,189 edible species, of which 2,006 can be consumed safely, and a further 183 species which required some form of pretreatment prior to safe consumption or were associated with allergic reactions by some. We identified 471 species of uncertain edibility because of missing or incomplete evidence of consumption, and 76 unconfirmed species because of unresolved, differing opinions on edibility and toxicity. This is the most comprehensive list of edible mushrooms available to date, demonstrating the huge number of mushrooms species consumed. Our review highlights the need for further information on uncertain and clash species, and the need to present evidence in a clear, unambiguous, and consistent manner.