低温等离子体对糙米蒸煮品质和物化特性的影响

本文以糙米为原料,探究了低温等离子体对糙米的营养成分、蒸煮品质、感官品质、质构特性、糊化特性、微观结构、结晶度和近红外图谱的影响。结果表明,相比较于对照组糙米,低温等离子体处理后糙米的加热吸水率、体积膨胀率和固形物损失率显著增加到236.10%、268.25%和19.18 mg/g (P<0.05);直链淀粉、蛋白质、膳食纤维和非必需氨基酸的含量也有一定程度的增加。低温等离子体处理改善了糙米饭的糊化特性、质构特性和感官品质,有利于糙米饭品质的提升。通过对低温等离子体处理后糙米皮层微观结构的观察分析,糙米皮层遭到破坏,表面出现凹陷和裂缝;X射线衍射和近红外数据分析得出,糙米经低温等离子体处理后亲水基团增加,结晶度降低,淀粉的晶体结构被破坏,从而有助于吸水速率提升。综上,低温等离子体可以有效地改善糙米的蒸煮和食用品质,研究结果可为低温等离子在糙米生产中提供参数指导。     

Multivariate analysis of the conditions of temperature,moisture and storage time in the technological,chemical, nutritional parameters and phytochemical of green lentils

The aim of this study was to determine appropriate conditions of temperature and moisture during a storage period of several months in the technological, chemical, nutritional parameters and phytochemical of green lentils. For this the experimental design adopted was completely randomized in a split-split plot scheme, with three replications. In the main plot, temperatures (15, 25 and 35 °C) were allocated; in the split plot the moisture (10, 12 and 14%); and, in the split-split plot, storage times (0, 60, 120, 180, 240, 300 and 360 days). At the end of 360 days of storage, it was observed that the grains maintained appropriate quality parameters at 15 °C/10% (temperature/moisture), followed by 25 °C/10% and 25 °C/12%. The storage time was proportional to the stress suffered by the grain, because in the three longest storage times (240, 300 and 360 days) in the three moistures, was observed a higher content of simple and total phenols, tannins and anion capture action evaluated by DPPH, as well as, greater darkening and brown tint. Significant reduction in nutritional compounds such as protein and lipid was also observed with the increase in storage time at all temperatures and moisture. In this way, this research also makes a significant contribution to producers and industries, so that in practice they can have appropriate storage conditions, reducing the technological, nutritional and economic depreciation of the grain, opening the horizon for a market that still needs to be better explored.     

旋转通风干燥仓高水分玉米降水实验研究

采用自主研发的旋转通风干燥仓,进行高水分玉米降水工艺研究。实验期间,对仓内粮堆不同位置的温度和湿度,及环境温湿度进行定时监测,并定时取样检测玉米水分和真菌孢子。结果表明:粮堆中各监测点的温湿度随环境变化而变化,相同层或相同列的检测点温湿度基本一致;在有降雪的情况下(实验第6天,雨转雪),18天内玉米水分由27.12%降至14.60%;玉米携带真菌孢子数保持在真菌生长的临界范围内,达到短期安全储存目标。因此,采用旋转通风干燥仓对高水分玉米进行降水的工艺是可行的,降水效果均匀、高效,有效保证粮食不发热霉变。同时,旋转通风干燥的方法不使用燃煤、燃气,符合我国当前环境保护和可持续发展的新要求,有显著的经济社会效益,可在大农户玉米干燥和短期安全储存中推广应用。     

基于免疫磁珠黄曲霉毒素全自动净化方法适用性评价

对基于免疫磁珠黄曲霉毒素全自动净化的方法适用性进行研究。结果表明:免疫磁珠试剂盒平均回收率均在95%以上,相对标准偏差小于3.3%。质控样品的测定结果均在给参考值范围内。通过t检验可知,sig.(双侧)=0.533,两台净化仪的检测结果没有显著性差异。通过62名检测人员对黄曲霉毒素免疫磁珠自动化处理方法与传统的免疫亲和柱净化法的评测,通过t-检验可知,99%的置信区间内,P值≥0.01,说明两种方法的测定值没有显著性差异,但是免疫磁珠自动化处理法测定结果的离散程度小于免疫亲和柱法,且全部的检测结果的|Z|均≤2。     

基于蒙特卡洛法评定花生油脂肪酸组成的不确定度

采用蒙特卡洛法(monte carlo method,简称MCM)评定气相色谱法测定花生油脂肪酸组成的测量不确定度。结果表明:花生油主要脂肪酸组分C16:0的不确定度为10.78%±0.23%,C18:0的不确定度为3.52%±0.08%,C18:1n9c的不确定度为45.75%±0.58%,C18:2n6c的不确定度为32.10%±0.52%,C22:0的不确定度为2.84%±0.07%,MCM法评定测量不确定度,避免对测量模型求偏导数等复杂的测量推导及不确定度的A类评定和B类评定过程,利用MCM软件可简便快速地求出花生油二十一种脂肪酸组分测量的不确定度,该法为提高实验室不确定度评定能力提供了技术支撑。     

酶解制备苷元型大豆异黄酮

以大豆异黄酮糖苷为原料,酶解制备苷元型大豆异黄酮。以水解率和苷元得率为指标对几种来源的β-葡萄糖苷酶、β-半乳糖苷酶、纤维素酶进行筛选,确定最适酶解用酶。通过单因素实验对酶添加量、底物质量浓度、酶解温度、pH、酶解时间进行优化。结果表明,最佳酶解工艺条件为：采用β-葡萄糖苷酶（300 U/g）,酶添加量7%,底物质量浓度1.6 mg/mL,酶解温度56 ℃,pH 4.8,酶解时间6 h。在最佳工艺条件下,大豆异黄酮糖苷的水解率及苷元得率分别达到96.84%和99.74%。     

重金属镉特异性抗体的制备及icELISA检测方法的建立

为检测食品中的重金属镉残留问题,本研究建立了基于重金属镉抗体的酶联免疫分析方法。利用异硫氰酸苄基乙二胺四乙酸(Isothiocyanobenzyl-EDTA,ITCBE)螯合Cd~(2+)并偶联牛血清白蛋白(BSA)和卵清白蛋白(OVA),合成了针对Cd~(2+)的免疫原Cd-ITCBE-BSA和包被原Cd-ITCBE-OVA,通过紫外扫描鉴定说明偶联成功;以Cd-ITCBE-BSA免疫Balb/c小鼠,制备出Cd~(2+)抗血清并对其免疫学特性进行鉴定,进一步说明了抗原合成成功,在此基础上进行了条件优化并建立了针对镉的icELISA检测方法。方法的检测限(IC10)为0.18 ng/mL,IC50为1.15 ng/mL,线性检测范围(IC20～IC80)为0.24～5.54 ng/mL。除了与Hg~(2+)有2.16%的交叉反应率,该方法对Pb~(2+)、Fe~(3+)、Cu~(2+)和Cr3+交叉反应率均小于0.3%,板内变异系数和板间变异系数都低于10%。此抗体特异性强灵敏度高,建立的icELISA方法可应用于食品中重金属镉的快速检测。     

不同全麦粉替代率对冷冻馒头品质的影响研究

目的 探讨不同全麦粉替代率对冷冻馒头品质影响的变化规律.方法 采用不同比例全麦粉(0、10％、20％、30％、40％、50％、60％、70％、80％、90％、100％)替代小麦粉,测定了混合粉的湿面筋含量和流变学特性,对比新鲜馒头,评价全麦粉替代率对冷冻馒头外观、质构和感官品质的影响.结果 随全麦粉替代率增加,面团湿面...     

气相色谱-三重四极杆质谱法测定稻米中27种持久性有机污染物

目的 建立气相色谱-三重四极杆质谱法测定稻米样品中多氯联苯、有机氯农药和多溴联苯醚等27种持久性有机污染物的分析方法.方法 糙米粉样品经水化后,采用乙酸乙酯进行2次直接提取,采用5 g酸性硅胶(44％,m∶m)固相净化柱进行净化后采用气相色谱-三重四极杆质谱在动态多反应离子监测模式进行分析,内标法定量.结果 27种持久...     

Optimization of unconstrained problems using a developed algorithm of spectral conjugate gradient method calculation

This paper presents a numerical investigation of the spectral conjugate directions formulation for optimizing unconstrained problems. A novel modified algorithm is proposed based on the conjugate gradient coefficient method. The algorithm employs the Wolfe inexact line search conditions to determine the optimum step length at each iteration and selects the appropriate conjugate gradient coefficient accordingly. The algorithm is evaluated through several numerical experiments using various unconstrained functions. The results indicate that the algorithm is highly stable, regardless of the starting point, and has better convergence rates and efficiency compared to classical methods in certain cases. Overall, this research provides a promising approach to solving unconstrained optimization problems.