Effects of non-thermal plasma treating wheat kernel on the physicochemical properties of wheat flour and the quality of fresh wet noodles

The effects of non-thermal plasma (NTP) on the physicochemical properties of wheat flour and the quality of fresh wet noodles ( FWN) were investigated. The results showed that NTP effectively decreased the total plate count (TPC), yeast and mould count (YMC) and Bacillus spp. in wheat flour. Wet gluten contents and the stability time reached the maximum when treated for 20 s. The viscosity of starch increased significantly after treatment due to the increased of damaged starch. The contents of secondary structure were altered to some extent, which was because that the ordered network structure of gluten protein broken. Furthermore, compared with the control, texture properties of FWN were enhanced significantly at 20 s, and the darkening rate of FWN was greatly inhibited due to the low polyphenol oxidase (PPO) activity. Consequently, the most suitable treatment was 500 W for 20 s, providing a basis for the application of NTP in flour products.     

Predicting Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae) populations and associated grain damage in smallholder farmers’ maize stores: A machine learning approach

Prostephanus truncatus is a notorious pest of stored-maize grain and its spread throughout sub-Saharan Africa has led to increased levels of grain storage losses. The current study developed models to predict the level of P. truncatus infestation and associated damage of maize grain in smallholder farmer stores. Data were gathered from grain storage trials conducted in Hwedza and Mbire districts of Zimbabwe and correlated with weather data for each site. Insect counts of P. truncatus and other common stored grain insect pests had a strong correlation with time of year with highest recorded numbers from January to May. Correlation analysis showed insect-generated grain dust from boring and feeding activity to be the best indicator of P. truncatus presence in stores (r = 0.70), while a moderate correlation (r = 0.48) was found between P. truncatus numbers and storage insect parasitic wasps, and grain damage levels significantly correlated with the presence of Tribolium castaneum (r = 0.60). Models were developed for predicting P. truncatus infestation and grain damage using parameter selection algorithms and decision-tree machine learning algorithms with 10-fold cross-validation. The P. truncatus population size prediction model performance was weak (r = 0.43) due to the complicated sampling and detection of the pest and eight-week long period between sampling events. The grain damage prediction model had a stronger correlation coefficient (r = 0.93) and is a good estimator for in situ stored grain insect damage. The models were developed for use under southern African climatic conditions and can be improved with more input data to create more precise models for building decision-support tools for smallholder maize-based production systems.     

低温豆粕中磷脂对蛋白提取率的影响

通过3次酸沉的方法从大豆蛋白提取液中分离出7S、11S及磷脂膜蛋白组分,对比了两种低温豆粕所制得的蛋白产品各组分中脂质的含量,分析了磷脂在低温豆粕中的残留情况以及磷脂对低温豆粕中蛋白溶解性的影响,认为残留的磷脂对低温豆粕中蛋白提取是不利的.     

三氟乙酸对几种植物油的显色反应

以三氟乙酸为显色剂,对芝麻香油、二级棉籽油、三级棉籽油、一级菜籽油、菜籽毛油5种植物油进行显色反应,并在350~700 nm波长进行紫外-可见光谱扫描.结果显示用三氟乙酸做显色剂能够很明显地将这5种植物油区分开来,所显示的颜色分别为:黄绿色、黄橙色、暗红橙色、红紫色、暗红橙色;并且上述5种植物油显色反应后的紫外-可见光谱扫描曲线差别很大,容易区分.     

抗性淀粉测定方法的研究

抗性淀粉的测定方法有Berry法、Englys法、Bjorck法、Champ法、Goni法等.以木薯抗性淀粉和抗性淀粉标准品为原料,通过对抗性淀粉的处理方法(AOAC法、Goni法)以及还原糖的测定方法(3,5-二硝基水杨酸法、D-葡萄糖法)进行对比,得到木薯抗性淀粉最适合的测定方法.同时也研究了样品多少对测定结果的影响.结果表明,AOAC-GOPOD法操作简单、准确性高、重复性好,酶用量充足,是测定木薯抗性淀粉的首选方法.     

Detection of the residues of nineteen pesticides in fresh vegetable samples using gas chromatography–mass spectrometry

In this study, we investigated the presence of 19 different agricultural pesticides in 210 samples of eight types of domestic vegetables collected from several vegetable-growing regions in Bangladesh. A multiresidue method was developed to detect the pesticide levels in the collected samples using gas chromatography with mass spectrophotometry (GC–MS). Pesticide residues were detected in 51.30% of the total samples, and among the positive samples, 38.89% contained levels above the maximum residue levels (MRLs). The most frequently detected pesticides were chlorpyrifos (34) followed by carbofuran (17), diazinon (16), carbaryl (14), malathion (11), endosulfan (8), cypermethrin (7) and dimethoate (6). Some (10.47%) of the samples contained multiple residues. It is concluded that the continuous monitoring and strict regulation of pesticide use on food crops, especially vegetables, are necessary.     

Effects of light exposure on chlorophyll,sugars and vitamin C content of fresh‐cut celery (Apium graveolens var. dulce) petioles

Effects of light exposure (24 μmol m^?2 s^?1) on fresh‐cut celery nutritional quality were evaluated during 8‐day storage at 7 °C using darkness as control. Light exposure preserved 47% chlorophyll a and 48% chlorophyll b contents more than darkness at the end of storage. Sucrose, reducing sugar and glucose contents in light‐stored petioles were 17%, 25% and 67% higher than those in dark‐stored petioles after 8‐day storage, respectively, thus resulting in higher total soluble solids content in light condition. Moreover, l ‐ascorbic acid content increased at 2‐day storage in light condition and was 46% more than in darkness at the end of storage. The fresh weight loss significantly increased in all petioles, and this increase was markedly accelerated by light exposure with a maximum of 1.43% at the end of storage. Dry matter content was induced more by light exposure than by darkness at 2‐day storage.     

Effect of ozone treatment on aflatoxin B1 and safety evaluation of ozonized corn

This paper studies the ozone treatment effect on degradation of aflatoxin B₁ (AFB₁) in corn with different moisture content (MC). The toxicity of the degradation products (DPs) of the ozone-treated AFB₁-Contaminated Corn (ACC) was also evaluated using the human hepatocellular carcinoma cell line (HepG2) as model cells. The degradation rate of AFB₁ in corn increases with ozone concentration and treatment time. The results showed that ACC with 13.47% MC was easier to be degraded by ozone than with 20.37% MC. Treated with 90 mg L⁻¹ ozone for 20 min and 40 min, AFB₁ in corn with 13.47% MC decreased from 83 μg kg⁻¹ to 18.12 μg kg⁻¹ and 9.9 μg kg⁻¹, respectively, well meeting the China National Standard of AFB₁ in corn (20 μg kg⁻¹). In order to evaluate the safety of ozone used on ACC, the impacts of AFB₁ as well as untreated and ozone-treated ACC with the same level of AFB₁ content on HepG2's survival rate, morphology, and apoptosis were studied. The results showed that ACC had high cell toxicity while the toxicity of ozone-treated ACC had no significant difference with that of the AFB₁-free culture solution. It is concluded that ozonation can quickly and effectively degrade AFB₁ in corn and diminish ACC's toxicity, and therefore, ozonation is expected to be an effective, fast, and safe method for AFB₁ degradation in ACC.     

Rapid detection method for aflatoxin B1 in soybean sauce based on fluorescent microspheres probe

Soybean sauce, a Chinese traditional and daily condiment, is often contaminated by aflatoxin B₁. An extract-free immunochromatographic assay was proposed based on fluorescent microspheres probe for the' detection of aflatoxin B₁ in soybean sauce. The probe was prepared by coupling fluorescent microspheres with anti-aflatoxin B₁ antibody by the 1-ethyl-3(3-dimethylaminopropyl) carbodiimides hydrochloride-mediated method. The background from the soybean sauce sample on strip was eliminated because of the optical property of the probe. The sample without extracting procedure was directly detected by diluting with 10% methanol solution. The visible detection limit for the qualitative analysis of aflatoxin B₁ in the proposed method was 2.5 μg/L, which was lower than the maximum level of 5 μg/L set by the Chinese government. The results were well agreed with those obtained by liquid chromatography-mass spectrometry (LC-MS). The method showed satisfactory characteristics, such as rapid detection, easy operation, and high sensitivity, and can thus be applied for the large-scale and on-site screening of soybean sauce contaminated with aflatoxin B₁. To our knowledge, this report is the first one on the qualitative detection of aflatoxin B₁ in dark colored food samples directly by fluorescent microspheres probe-based immunochromatography.     

复合酶法制备小麦面筋蛋白咸味酶解液的工艺优化

为优化小麦面筋蛋白咸味酶解液的制备工艺,并考察其咸度及分子量大小.基于单因素实验,采用Box-Behnken响应面法,以酶添加量、酶解pH、底物浓度以及酶解温度为考察因素,水解度为指标,优化小麦面筋蛋白咸味酶解液的制备工艺,并采用电子舌测定其咸度;高效液相色谱测定其分子量分布.结果表明:制备小麦面筋蛋白咸味酶解液的最优...