玉米胚芽油辅助降血脂效果临床观察

为研究玉米胚芽油的辅助降血脂作用,将162名高脂血症志愿者随机分为试验组、阳性对照组、阴性对照组等3组,其中,试验组采用玉米胚芽油替代午餐、晚餐烹调用油(每餐10ml);阳性对照组采用XX牌玉米胚芽油胶囊每日午餐、晚餐后各1粒;阴性对照组只做体检,不进行任何干预,观察期45d。通过试验组自身比较及试验组与空白对照组组间比较可得,血清胆固醇、甘油三酯均存在显著性差异(P0.01),血清高密度脂蛋白未见显著性差异(P0.05)。试验组与阳性对照组比较发现,血清总胆固醇、甘油三酯降低幅度略大,但未见显著性差异。试验组血清胆固醇有效率、甘油三酯有效率及总有效率明显高于空白对照组,差异均存在显著性(P0.01);高于阳性对照组,但未见显著性差异(P0.05)。在试验期间受试者的精神、睡眠、饮食、大小便、血压、各项临床指标等均未见异常,也未见其它不良反应。     

Impact of moisture content and maize weevils on maize quality during hermetic and non-hermetic storage

The objective of this study was to determine the impact of moisture content and Sitophilus zeamais Motschulsky on maize quality during hermetic and non-hermetic storage conditions. Commercial Channel 211-97 hybrid maize kernels were conditioned to 14, 16, 18, and 20% moisture content (wet basis), and then three replications of 300 g of maize grain were stored in glass jars or triple Ziploc^® slider 66-μm(2.6-mil) polyethylene bags at four conditions: hermetic with weevils, hermetic no-weevils, non-hermetic with weevils, non-hermetic no-weevils. All jars and bags were stored in an environmental chamber at 27 °C and 70% relative humidity for either 30 or 60 d. At the end of each storage period, jars and bags were assessed for visual mold growth, mycotoxin levels, gas concentrations, pH level, the numbers of live and dead S. zeamais, and maize moisture content. The maize stored in non-hermetic conditions with weevils at 18 and 20% exhibited high levels of mold growth and aflatoxin contamination (>150 ppb). Conversely, very little mold growth was observed in maize stored in hermetic, and no aflatoxins were detected in any moisture level. CO₂ increased and O₂ gradually decreased as storage time increased for maize stored in hermetic conditions (with or without weevils) in all moisture level. No significant difference in pH was observed in any storage conditions (P < 0.05). Total mortality (100%) of S. zeamais was observed in all hermetically stored samples at the end of 60 days storage. Moisture content for hermetically stored maize was relatively constant. A positive correlation between moisture content and storage time was observed for maize stored in non-hermetic with weevils (r = 0.96, P < 0.05). The results indicate that moisture content and the number of S. zeamais weevils plays a significant role in maize storage, both under hermetic and non-hermetic conditions.     

Comparative effects of hermetic and traditional storage devices on maize grain: Mycotoxin development,insect infestation and grain quality

A large-scale study was conducted to assess which of the five most accessible hermetic storage devices on the Kenyan market fulfill the needs of smallholder farmers by positively impacting three major areas of concern: insect infestation, grain quality, and mycotoxin (aflatoxin and fumonisin) contamination. Efficacy of two hermetic silos (plastic and metal) and three hermetic bags (PICS, GrainPro's GrainSafe™, and Super Grain) was directly compared to current maize storage in polypropylene (PP) bags under local environmental conditions using representative storage volumes during a 6-month storage period. Impact of maize grain stored at typical (∼15%) and recommended (<13.5%) moisture levels and potential efficacy losses through frequent interruption of the underlying hermetic principals was assessed. Hermetic storage significantly reduced the increase in aflatoxin compared to PP bags regardless of the moisture level of the grain. An <5% per month aflatoxin increase was achieved by three of the five devices tested: Metal silo, PICS and GrainSafe™ bag. A strong correlation between grain moisture, storage time and aflatoxin development was found in PP bags, but not in any of the hermetic devices. The same result was not obtained for fumonisin development in stored maize. The rate of Fumonisin increase was similar in all tested devices, including the polypropylene bags, and conditions. The periodic opening of the hermetic devices had no significant effect on the efficacy of the hermetic devices but the repeated disturbance of the PP bags led to a significant increase in aflatoxin levels. The maize weevil Sitophilus spp. was most commonly found with a total incidence of 72%. Grain storage under hermetic conditions reduced insect infestation, grain weight loss and discoloration. However, maize storage above recommended moisture levels led to a distinct odor development in all hermetic devices but not the PP bags. Hence, proper grain drying is a prerequisite for maize storage in airtight conditions.     

追氮对夏玉米淀粉含量及其糊化特性的影响

以郑单958为材料,研究玉米随追氮量增加玉米籽粒淀粉含量、淀粉相关酶活性及其淀粉糊化特性的影响,研究结果表明玉米籽粒淀粉及直链淀粉含量随追氮量的增加先升高后略有下降;腺苷二磷酸葡萄糖焦磷酸化酶(ADPG-PPase)、尿苷二磷酸葡萄糖焦磷酸化酶(UDPG-PPase)及束缚态淀粉合成酶(GBSS)的活性随追氮量的增加先升高后降低。可溶性淀粉合成酶(SSS)的活性随追氮量的增加先降低后升高;随追氮量的增加淀粉的峰值黏度、低谷黏度、最终黏度及崩解值先升高后降低,峰值时间以及糊化温度先降低后升高。     

基于改进CBAM注意力机制的MobileNetV2玉米种子品种识别研究

玉米是我国主要粮食作物,有较高的营养价值和经济价值。不同的地域环境适宜种植的玉米品种不同,但由于玉米种子在外形方面存在的差异较小,所以仅凭肉眼很难对其进行快速准确的识别。为实现玉米种子品种的准确识别,本研究采集了9种玉米种子图像共2792张建立数据集,并按照7：2：1的比例随机划分训练集、验证集和测试集。本研究将注意力机制CBAM引入轻量化模型MobileNetV2,对CBAM的串行方式进行改进,构建一个新型注意力模块E_CBAM,并通过对比不同的压缩比,选出效果最佳的压缩比为4,提出了E_CBAM_MobileNetV2模型。实验表明E_CBAM_MobileNetV2的准确率为98.18%,相较于MobileNetV2提高了5.45%。本研究为玉米种子的高效、便捷、快速识别提供了理论依据,同时为推动自动化检测玉米品种的手段提供了技术基础。     

Pasting and rheologic properties of potato starch and maize starch mixtures

This study characterized the pasting and rheologic behavior of potato/maize starch mixtures of various ratios. Pasting analysis using a Brabender Viscograph indicated that most important pasting parameters did not show a linear change that reflected the ratio of starches. A significant effect on final viscosities and setback was evident. The diameter distribution of starch granules that were heated to 70°C was determined by a laser particle size analyzer. The result suggested that the swelling of starch granules in the mixtures was reduced at the onset of gelatinization. Measurement of dynamic viscoelasticity measurement demonstrated that the mixtures showed slightly higher loss modulus than those seen for the control at small measuring frequencies. The mixture pastes with a high proportion of potato starch exhibited more pseudoplasticity and had a more significant thickening effect than either control paste. Nonadditive behavior was found by mixing potato and maize starch. This suggests that an appropriate blend of starches from diverse botanical origins may provide a simple practical avenue for manipulation.     

免疫快速同步检测玉米中五种真菌毒素胶体金试纸条的构建和应用

玉米作为重要的粮食和饲料来源，容易受到多种真菌毒素的污染，给居民健康和养殖业造成严重的危害。本文优化了适合五种真菌毒素（黄曲霉毒素B1、伏马毒素、T-2毒素、脱氧雪腐镰刀菌烯醇和玉米赤霉烯酮）同时提取的样品前处理方法，并构建了五检测线胶体金试纸条，检测结果可以通过肉眼定性，结合Image J软件可以进行定量分析，并应用于实际玉米样品检测。结果表明，最佳提取条件为90%乙腈/水，涡旋20 min，样品的添加回收率为71.9%-113.3%，相对标准偏差为0.9%-7.5%；测定基质添加样品建立标准曲线，通过肉眼判定得到五种真菌毒素的消线值分别为80.0、1000.0、100.0、400.0和200.0 μg/kg；结合Image J 软件提取多重检测试纸条的检测线灰度值，结果表明当AFB1、FB1、T-2、DON和ZEN的浓度为8.0、20.0、10.0、40.0、20.0 μg/kg时，各真菌毒素浓度对应的检测线显色值比空白对照显色值低。最后，通过检测11个实际玉米样品，结果表明部分玉米样品受到了不同程度的AFB1、DON和ZEN的污染。因此，本研究开发的免疫快速同步检测玉米中五种真菌毒素胶体金试纸条可以用于玉米中真菌毒素的现场快速筛查。     

Evaluation of the Degree of Starch Gelatinization by a New Enzymatic Method

In this work, a new enzymatic method is proposed to evaluate the degree of starch gelatinization in starchy food and feed. The procedure developed is based on the fact that the gelatinization process enhances the chemical reactivity of inert starch granules towards amylolytic enzymes. Aqueous suspensions of maize starch were treated at different temperatures to obtain different degrees of gelatinization, from 25 °C (control without gelatinization) until 95 °C. Heated samples were then incubated with a glucoamylase. The enzymatic activity was measured by the glucose released during the digestion time by using a standard glucose oxidase method. The initial velocity value of the enzymatic reaction (V_i) was selected as the parameter to quantify the degree of starch gelatinization (DG). Changes in granule morphology and the starch available for hydrolysis were evaluated by photomicrographs. The new method was standardized and compared with DSC and viscosity measurements in order to check its efficiency, considering the DG observed by photomicrographs. A good agreement was observed between the DG calculated by V_i and by DSC (correlation coefficient r = 0, 97), thus V_i reflect the degree of starch gelatinization as well as DSC. These results show that the developed enzymatic procedure is an effective method to evaluate the DG in starchy foods and feeds.