进口大豆储运温度和含水量对大豆发生热损伤的影响北大核心CSCD

通过模拟进口大豆在海运中的环境,结合生物调查统计中被害指数的原理,引入指标热损伤平均级值,探讨进口大豆在不同的储运温度和含水量下发生热损伤的情况。结果表明:进口大豆的含水量和储运温度是热损伤发生的直接影响因素,在30、40、50、55℃下储藏28 d,含水量小于等于13%的大豆发生热损伤的进程较慢,试验样品的热损伤平均级值均未达到热损伤粒程度的级值,说明大豆含水量小于等于13%,温度低于55℃的条件下,短期储存中大豆发生热损伤的程度较低,进程较慢;破碎粒大豆比完整粒大豆容易发生热损伤,并且发生热损伤的程度也相对高;巴西大豆比美国和阿根廷大豆容易发生热损伤,且发生程度也相对较高。     

不同水分含量大豆在模拟储运期间的品质变化

以巴西大豆为试验材料,模拟海上货轮舱内环境,对大豆热损伤粒率、霉变粒率、粗蛋白质含量、粗脂肪含量、蛋白质溶解度和脂肪酸值进行测定,监测不同水分含量大豆在50 d模拟储运期间的品质变化。结果表明,大豆水分含量越高,对豆堆温度的影响越大,进而对大豆的品质影响越大。当大豆水分含量小于等于12%时,各项指标均未发生明显变化,可长期安全储存;当水分含量为13%时,储存时间超过20 d后品质指标开始发生较明显变化;大豆水分含量大于等于14%时,短期内大豆各项指标发生显著变化,不耐储存。高水分导致豆堆温度升高,进而引起大豆霉菌滋生,热损伤粒率、霉变粒率、脂肪酸值增加,蛋白质溶解度降低,粗蛋白质和粗脂肪含量轻微下降。研究结果可为科学阐述进口大豆海上运输过程中品质变化和客观评估经济损失提供理论依据。     

进口大豆对国内市场影响

分析了进口大豆快速增长的因素及国产大豆不敌洋大豆的原因即：①流通成本高；②没有资金优势；③补贴低；④进口关税低，并阐述了不能限制大豆进口的理由，指出了进口大豆没有对油脂行业造成影响。     

进口大豆热损贬值的因素分析与评估

随着大宗油料国际贸易的发展,进口油料货损难以避免,其中又以油料热损最为突出。油料热损与运输业、保险业、油脂加工业等多个行业的权益相关,如何正确认识并计算热损所造成的经济损失被各方高度关注。基于近年来参与进口大豆若干热损案例的经验,针对热损大豆原料和油、粕产品,分析其品质受损的原因和主要因素,为热损贬值评估提供理论和技术依据。在通常情况下,建议通过蛋白溶解度的损失率和毛油酸价的升高分别计算豆粕和大豆油的损失,进而反映热损大豆的贬值情况;也可将粕和油的损失分别折算成热损大豆的量,以反映贬值情况,但此时应避免重复计算。     

我国大豆进口对大豆产业安全带来的影响及对策分析

在探讨我国大豆种植业发展的现状和存在的问题基础上,分析了大豆产业供需结构和国际资本冲击对我国大豆产业安全的影响。提出了包括种植补贴、非转基因扶持、技术提升、定价权以及绿箱政策在内的农业政策和贸易政策相结合的大豆产业综合安全政策,对缓解我国大豆产业危机和保障粮食安全都具有非常重要的现实意义。     

蜂蜜含水量,贮存温度对其结晶的影响

本文研究了蜂蜜贮存过程中影响结晶的环境温度，水分含量及蜂蜜成分等因素。结果表明，蜂蜜在４￣２７℃变温的条件下，水分含量小于２３％时最易形成结晶，在恒温环境下，１２℃时蜂蜜也易形结晶。     

通风对进口大豆货损的影响

除了水分和温度是影响进口大豆货损的重要原因之外,海上运输期间船舱通风也是争论的焦点。对运输大豆的船舱构造进行模拟,通过持续通风储存和不通风储存的对比,考察通风对进口大豆货损的影响。结果表明:水分含量为9.9%的大豆,无论通风与否,在储存期间均不会发生霉变;水分含量为14%~16%的大豆,即使储存期间不间断通风,也会在短时间内迅速发生霉变,与不通风条件下储存相比大豆霉变速度和程度相同。因此,通风与否和大豆货损无直接关系。     

进口热损大豆生产成本分析

进口巴西大豆常会出现不同程度的热损,为明确热损大豆在生产加工时所增加的成本和带来的多项问题,对热损大豆加工大豆脱胶油和精炼大豆油的成本进行分析。结果发现,热损大豆生产大豆脱胶油的成本比正常大豆增加6.2元/t,精炼成本增加14.33元/t。热损大豆加工制备精炼大豆油,油脂得率下降,所得油脂品质和豆粕品质下降,皂脚和脱臭馏出物等副产品产量增加。可通过将热损大豆和正常大豆按一定比例混合,或保障所购大豆在运输和加工过程中的环境条件以保证大豆品质,还可在采购、海运、保险合同中签订相关条款,以降低热损大豆对企业造成的损失。     

我国大豆压榨行业对进口大豆的依赖性将持续增强

近年来我国对豆油和豆粕的需求量不断增加，进而带动国内大豆压榨量逐年提高．在国内大豆产量供不足需的情况下，大豆压榨行业对进口大豆的需求持续大幅增加，1995／1996年度我国首次从大豆净出口国变成大豆净进口国．当时年度大豆进口量只有79．5万t．到2005／2006年度我国大豆进口量已经达到2831．7万t，10年间大豆进口量增加了34．6倍。1999／2000年度我国进口大豆压榨量首次超过国产大豆压榨量．     

高温储藏条件下不同水分含量小麦品质变化研究

以开麦21为原料,对其进行鼓风干燥和调质处理,使其水分含量分别为12.5%,9.5%,7.7%和5.9%,在35℃下密封储藏,研究其储藏过程中生活力、电导率、过氧化氢酶活动度、湿面筋含量、干面筋含量和面筋吸水率的变化,探讨高温密闭储藏下小麦的水分含量与其储藏品质变化的规律。结果表明:35℃条件下,水分含量高的小麦其生活力、过氧化氢酶活动度、湿面筋含量和面筋吸水率降幅大;水分含量为7.7%的小麦电导率增幅最小。     

Influences of storage time and temperature on the xanthophyll content of freeze-dried egg yolk

The influences of storage time, temperature (−18 or +20 °C, both in the dark), and prior pasteurisation on the xanthophyll content of freeze-dried egg yolk were investigated. After six months of storage, the synthetic xanthophylls all-E-canthaxanthin and β-apo-8-carotenoic acid ethyl ester showed considerably higher stability (with losses of 19–34%) than did the natural pigments all-E-lutein and all-E-zeaxanthin (losses of 59–69%). At all stages of storage, the xanthophyll contents of unpasteurised and previously pasteurised samples did not differ significantly, and no obvious influence of storage temperature was observed. With respect to xanthophyll content, the results suggest that there is no necessity for low-temperature storage of freeze-dried egg yolk.     

稻谷储存水分和温度对真菌生长和稻谷主要品质的影响

研究水分、温度对稻谷储存过程中真菌生长和主要储存品质的影响。将稻谷设为含水量分别为12.1%、13.1%、14.0%、15.1%、16.0%的样品,分别置于10、15、20、25、30、35℃温度条件下模拟储存180 d后,检测稻谷样品中真菌生长、发芽率和脂肪酸值的变化。结果表明,水分是真菌生长的决定因素,13.1%水分处于真菌生长临界水分以下,即使温度适宜真菌也不生长;14.0%处于真菌生长临界水分以上,水分越高越利于真菌孢子萌发生长,温度越高真菌生长速度越快;脂肪酸值受真菌生长的影响程度要大于水分和温度,13.1%以下水分稻谷,没有真菌生长,脂肪酸值上升缓慢。14.0%以上水分稻谷,一旦真菌生长,就会加速脂肪酸值的升高;发芽率受温度影响程度最大,高温储存半年,无论是否有真菌生长,发芽率基本降为0,低温储存不仅能抑制真菌生长还利于保持种子发芽率。     

Determination of safe storage moisture content of soybean expeller by means of sorption isotherms and product respiration

Soybean expeller (SBE) is rich in protein and has a relatively high and variable oil composition (7–15%). With the increasing use of the SBE for animal nutrition there arose a need for understanding the quality deterioration during storage. The goal of this research was to determine the storability of SBE by developing a model for predicting its equilibrium moisture content (EMC), using the EMC model to determine its safe storage moisture content (SSMC), and by measuring dry matter loss (DML) for SBE incubated at 10 °C and 20 °C for 46 days. Samples of SBE with different residual oil contents were collected and an EMC experiment was carried out to determine the sorption isotherms at 65, 70, 75 and 80% RH; at 10 and 20 °C for samples with 6.2, 9.6 and 15.3% oil content. A second set of samples was used for determining the respiration rate at 20 °C. The Enhanced Halsey model was fitted to the SBE EMC/equilibrium relative humidity (ERH) data and it was established that the residual oil content significantly affected the sorption isotherms. By considering an ERH of 67% or below to be a safe storage condition, the SBE should be stored at or below 12.2% moisture content (m.c.) if the temperature is at or below 20 °C and an the oil content is 7%. However, according to the respiration experiments it would be safe to store SBE up to 16% m.c. (equivalent to 75% ERH). Considering a DML limit of 0.1%, the allowable storage time of SBE at a m.c. lower than 15.4% (ERH of 75%) was at least 46 days. The widely accepted practice of incorporating the gums present in the extracted oil, diluted in water, back into the SBE should be avoided since it increases the m.c. of the product and substantially reduces the allowable storage time.     

高水分成品大米低温储存及低温解除后品质变化研究

通过对东北高水分粳米低温储存及解除低温后的试验研究,探索高水分大米低温储存品质变化规律。结果表明:大米初始水分为17.54%,在温度低于15℃、相对湿度60%~70%的条件下,储存10个月,大米水分维持在16.0%,脂肪酸值低于25 mgKOH/100 g,大米品质无明显劣变,在宜存范围内。储存过程中大米L值降低,b值升高,a值变化无明显规律。TPA质构分析显示,蒸煮米饭硬度增大,黏性、弹性下降,内聚性增加。储存6个月后,各项指标发生明显变化。低温解除后,在夏季,高水分大米储存1个月后发生霉变,水分、脂肪酸值、色差值均发生明显变化。扫描电镜观测结果表明:随储藏时间延长,米粒表面裂纹空隙增大,淀粉粒裸露,去胚部后形成空洞。胚乳细胞表面小孔增多变大,细胞表面被包裹的复合淀粉体之间的界限变得模糊,蛋白质膜明显翘起。     

Effect of oxygen and storage temperature on intermediate moisture meat products

During storage of glycerol desorbed intermediate moisture meats at 38°C it was found that, for both protein crosslinking and loss of haemoprotein character to occur, oxygen must be present. However, collagen degradation, as monitored by the formation of water-soluble hydroxyproline containing fragments, still occurred in the absence of oxygen although the rate of degradation was slower than that observed in aerobically stored samples. The rates of the various deteriorative reactions also varied with storage temperature, there being the expected decrease in rate with temperature for both the crosslinking and haemoprotein breakdown reactions. However, the temperature dependence of the collagen breakdown reaction was apparently more complex as there was no measurable breakdown, even during several months of storage, at temperatures of 17°C and below.     

Effect of moisture content, storage temperature and storage period on colour, ascorbic acid, lycopene and total flavonoids of dried tomato halves

Dried tomato halves with three storage moisture contents [18%, 24% and 30%, wet basis (wb)], packed in glass jar, plastic container and polyethylene bag were stored in room and cool-chamber environments for 5 months. During storage period average room and cool-chamber temperatures were 20 ± 4 and 5 ± 1 °C respectively. Changes of colour, ascorbic acid, lycopene, total flavonoids and moisture contents were monitored 1-month interval. Significantly higher losses of colour, ascorbic acid, lycopene and total flavonoids were found for room environment than those of cool chamber. A set of regression equations had been developed for colour, ascorbic acid, lycopene and total flavonoids as a function of storage time. No visible microorganisms were detected in the samples during the storage period. Dried tomato with ≤24% (wb) moisture content may be recommended to store in cool chamber (5 °C) and ≤18% (wb) to store in room environment (20 °C) both to be packed in glass jar.     

空调控温技术在偏高水分稻谷储藏中的应用

针对稻谷的储藏不稳定性,利用空调对高大平房仓散存偏高水分稻谷进行仓温控制,把粮堆表层平均粮温控制在20℃以内,创造准低温的储粮环境,有效控制稻谷表层粮温的上升,抑制虫霉繁殖,减少储粮污染,保证储粮品质,减少水分损耗,增加储粮经济效益和社会效益。     

水分对优质稻储藏品质的影响

为改善优质稻储藏入库前含水量,本研究以不同水分梯度(11.5%、12.5%、13.5%、14.5%、15.5%、16.5%)的优质稻为研究对象,通过放入15、20℃进行模拟储藏。研究储藏过程中其整精米率、发芽率、发芽势、脂肪酸值、峰值黏度的变化情况。结果表明:准低温下储藏,含水量为12.5%～14.5%范围内整精米率较好,含水量为14.5%以下,其发芽率、发芽势较好,含水量为12.5%～15.5%都能保证脂肪酸值在较好水平,含水量对稻谷糊化特性影响较显著,含水量较低时峰值黏度较低,含水量升高峰值黏度逐渐升高;准低温以下温度储藏对优质稻整精米率、发芽率、发芽势影响不大,温度越高脂肪酸值、降落数值增加越快,RVA糊化特性受温度影响较大,温度高峰值黏度变化快。