储藏温度对稻谷品质和微生物含量的影响

温度直接影响稻谷储藏品质与储藏时间,是稻谷储藏过程中的关键控制因素。实验测定了不同储藏温度下稻谷的水分、容重、出糙率、发芽率、还原糖及脂肪酸值各项品质指标,同时考察了温度对微生物生长的影响。结果表明,对同一个指标来说,温度越高,变化越剧烈。同时温度对各指标的影响程度又不尽相同。发芽率受温度的影响最大,15℃的储藏环境中降低了2%,而在35℃储藏条件下降低了9%;脂肪酸值在15℃的储藏条件下增加了0.9%,而在35℃条件下增加了18.3%。另外温度对储藏稻谷的微生物含量有显著影响,15℃下,微生物的菌落总数与初始相比减少了200 cfu/g,而当在高温环境中,特别是35℃下,微生物的菌落总数增加到7200 cfu/g。     

粮堆不同部位微生物活动的差异性研究

研究了粮堆不同部位微生物活动的特性,结果表明,杂质含量2%的稻谷储藏22d后(30℃、RH90%-100%)微生物活性值比含杂1%的稻谷高3.73倍。实仓储粮检测也表明,稻谷粮堆四周靠墙处和冬季粮堆中层、夏季粮堆下层都是微生物容易生长活动的部位。     

谷外糙米含量对稻谷储藏品质的影响

为了探讨稻谷中谷外糙米的含量对稻谷储藏品质的影响,确定稻谷中谷外糙米含量的临界值,对粳稻和籼稻样品分别加入2%、4%、6%、8%、10%的谷外糙米,以不添加谷外糙米的净稻谷和糙米作对照,在38℃,RH=75%的条件下储藏3个月,测定储藏品质,并用SPSS软件分析测定数据。结果表明,随着储藏时间的延长,脂肪酸值和丙二醛含量逐渐增高,还原糖含量上升后下降,与未添加谷外糙米的稻谷相比,添加不同含量谷外糙米的稻谷储藏品质均有不同程度的下降,谷外糙米含量越高,储藏品质指标越差。采用差异性分析法分析储藏90 d后谷外糙米含量对粳稻、籼稻品质的影响,不同含量的谷外糙米对稻谷储藏品质指标存在显著的影响。当粳稻谷外糙米含量超过8%,籼稻谷外糙米含量超过6%时,与净稻谷(0%)相比,脂肪酸值、还原糖含量和丙二醛含量均存在显著差异。粳稻谷外糙米含量不宜超过8%,籼稻谷外糙米含量不宜超过6%。     

高温、高湿条件下模拟仓储小麦品质与微生物群落结构的变化

研究小麦从入库储藏到发现菌丝体过程中,其品质和微生物群落结构的变化趋势。以天津市实仓储藏的硬质白小麦籽粒为研究对象,以三角瓶为储藏容器,分别在30 ℃、60%RH,40 ℃、80%RH条件下对小麦进行模拟仓储,储藏时间为0~120 d。通过监测小麦籽粒的水分、色差、蛋白质、脂肪、淀粉、脂肪酸等品质指标变化,以及霉菌总数、高通量测序结果评估模拟粮库中小麦在不同储藏阶段的品质与真菌群落结构变化。结果表明,在30 ℃、60%RH条件下,储藏120 d内,小麦品质呈缓慢下降趋势,80~120 d曲霉属相对丰度迅速增加。在40 ℃、80%RH条件下,小麦品质劣变更快,在60 d时曲霉属相对丰度达100%,小麦产生可见菌丝体。研究表明随着储藏温度与相对湿度的升高,小麦品质变化速度明显加快,菌丝体产生速度加快。     

小麦储藏期间霉菌早期活动的快速监测*

将小麦置于不同温、湿度组合条件下进行模拟储藏,利用快速测定微生物活性值(基于过氧化氢酶活性)的方法监测小麦中霉菌的早期活动状态。结果表明,小麦储藏在70%~79%相对湿度条件下49 d,各试验组微生物活性检测的最大值为306 u;当储藏的相对湿度超过80%时,28℃试验组小麦储藏14 d后的微生物活性检测值即大于500 u。分析微生物活性值与小麦品质的关系表明,当检测值达到400 u时,检验发现小麦的品质有轻微劣变迹象。进一步研究还发现,小麦在各种环境条件下储藏的微生物活性变化与储藏时间有较好的线性关系,其线性相关性系数均达0.9或更高。因此,利用监测微生物活性值变化的方法可以对小麦储藏期间霉菌活动危害做出早期预警。     

粮堆不同部位微生物活动的差异性研究

研究了粮堆不同部位微生物活动的特性，结果表明，杂质含量2％的稻谷储藏22d后（30℃、RH90％-100％）微生物活性值比含杂1％的稻谷高3．73倍。实仓储粮检测也表明，稻谷粮堆四周靠墙处和冬季粮堆中层、夏季粮堆下层都是微生物容易生长活动的部位。     

臭氧处理高水分稻谷储藏的研究

研究了臭氧处理对高水分稻谷品质与微生物量的影响,并根据臭氧处理后稻谷储藏过程中霉变、发芽率与脂肪酸值的变化规律,优化了储藏工艺条件。结果表明:臭氧处理对稻谷感官品质和发芽率没有影响,脂肪酸值略有增加,微生物量明显降低。臭氧处理组稻谷在不同温度储藏,随着时间的延长,与对照相比,霉变时间呈不同程度的延迟,发芽率在同温度时呈基本一致的下降趋势,而脂肪酸值增加,幅度与臭氧处理质量浓度和储藏温度有关,15℃时,呈上升趋势,且臭氧处理质量浓度越高,增加越快,而25、35℃储藏,呈先上升后下降趋势,95 mg/kg臭氧处理的稻谷尤为明显。进一步的SPSS分析表明,稻谷发芽率与储藏温度和时间呈显著的二元线性关系,脂肪酸值与臭氧处理质量浓度、储藏温度和时间呈显著的三元线性关系。因此臭氧处理高水分稻谷储藏优化的工艺条件为臭氧处理质量浓度55 mg/kg,储藏温度15℃,储藏时间60 d。     

氮气气调储藏下不同温度对晚籼稻品质的影响

目的 探究氮气气调结合控温储藏对晚籼稻品质的影响。方法 本研究以广西桂林新收获的晚籼稻为对象,采用99%浓度的氮气包装,在高温(35℃)、常温(25℃)、低温(15℃)3个条件下的恒温培养箱中进行180 d的储藏。同时设立常规储藏条件作为对照,每30 d取一次样,进行加工、储藏品质及米饭蒸煮品质指标的测定。结果 在3个温度条件下,相比于常规储藏,氮气气调稻谷能够有效延缓出糙率和水分的下降。在35℃条件下,氮气气调稻谷的整精米率、品尝评分值下降幅度及黄粒米率、脂肪酸值、直链淀粉含量、米饭吸水率的上升幅度均较大。在15℃和25℃条件下,氮气气调稻谷则能够有效延缓整精米率和品尝评分值的下降,并抑制黄粒米率、脂肪酸值、直链淀粉含量和吸水率的上升。在25℃和35℃条件下,氮气气调能够抑制蒸煮后体积膨胀率的上升,但在15℃条件下的效果不明显。相关性分析显示,在种子储藏时应避免使用氮气气调。主成分分析结果表明,在25℃条件下,氮气气调比低温常规储藏效果更好,能够延缓稻谷品质劣变。而品质特征指标与储藏条件的相关性分析结果表明,储藏温度对稻谷品质的影响较小。结论 将温度控制在25℃的氮气气调储藏方式在经...     

进口大豆与国产大豆抗霉变特性比较

研究了进口大豆和国产大豆在模拟储藏条件下微生物活性值、主要品质指标及吸湿性的变化.结果表明,在25℃、相对湿度80%-90%的条件下储藏14d,相同原始水分(11%)的进口大豆比国产大豆的微生物活性值增幅高151u,脂肪酸值和可溶性氮含量的增加更快;进口大豆在70%～100%相对湿度范围内的吸湿速率均明显高于国产大豆.     

主要粮食品种储藏期间霉菌活动特性研究

研究了稻谷、玉米和小麦在25℃,相对湿度分别为75%、85%和95%储藏,以及在高于安全水分2%的相似水活度条件下储藏期间霉菌的活动特性.结果表明,小麦最易出现霉菌生长活动,稻谷的抗霉菌生长作用最强,玉米介于小麦和稻谷之间;其中85%相对湿度下储藏至28 d,小麦的微生物活性值升高了475 u,分别是稻谷和玉米同期升高值的5.6和3.5倍.储粮中霉菌活动特性的不同表现与各粮种的吸湿性能及粮粒外皮(颖壳或种皮)的霉菌可生长性差异有关,但将相同霉菌活动强度的储粮样品作相关品质指标的检测,发现小麦的黏度、发芽率变化不明显,而玉米和稻谷的脂肪酸值和发芽率则有较大的变化.因此,对于储藏品质较稳定但易滋长霉菌的小麦应该重点关注霉菌活动的状况,仅仅监测品质指标变化难以准确判断储藏的安全性和粮食相关的食品安全性.     

BARLEY AND MALT TANNINOGENS AND BEER QUALITY

Anthocyanogen and catechin contents (tanninogen values) were determined for ten two-row and thirteen six-row barleys and for their corresponding malts. Four barley-malts were then selected for brewing, one with high, one with low, and two with intermediate tanninogen contents. The brews were made using bottom-fermenting (lager) as well as top-fermenting (ale) yeasts, both at 50–55° F. and at 68° F. The quality of the beers, as expressed by standard analyses and flavour evaluation, is discussed in the light of the tanninogen contents of the barleys and the different brewing parameters (yeast type and fermentation temperature).     

新合纤及其制造加工技术

说明了日本新合纤(新聚酯)的发展阶段,介绍了国外(日本西欧和美国)新合纤的市场情况,指出了日本在新合纤领域目前处于世界最先进水平。概括了新合纤制造加工技术及1990～1992年间日本各合成纤维厂商推出的新合纤产品。最后指出了新合纤存在的某些缺点。     

姜与人体营养健康

对姜的营养、保健功能及其在日常生活中的应用进行了介绍，更利于推动我国调味品业的进一步研究与开发。     

CHEMICAL AND ANTIOXIDANT PROPERTIES OF CULTIVATED AND WILD FRAGARIA AND RUBUS BERRIES

ABSTRACT

Content of individual sugars, organic acids, total phenolics (TPH), some important phenolic compounds (kaempferol, myricetin, quercetin, and ellagic acid) and total antioxidant capacity (TAC) in the fruits of strawberry, raspberry and blackberry were studied. A comparison was made between cultivars and wild relatives of each species (Fragaria vesca L., Rubus idaeus L. and Rubus fruticosus L.). The main sugars found were fructose and glucose both in the fruits of wild species and the studied cultivars. Citric acid was determined to be the major organic acid in most of tested berries with the exception of blackberry cultivars, where malic acid was dominant. The content of individual phenolic compounds varied among the wild species, as well as among the studied cultivars. Ellagic acid content was higher in F. vesca, R. idaeus and R. fruticosus (122.5 µg/g FW, 12.71 µg/g FW and 61.7 µg/g FW, respectively) than that obtained in analyzed cultivars. Overall, TPH expressed higher values in the wild strawberry and blackberry species in comparison to the studied cultivars, and consequently, the highest levels of TAC were recorded in F. vesca (5.78 mg asc/g FW), followed by R. fruticosus (4.95 mg asc/g FW).

PRACTICAL APPLICATIONS

In recent years, both wild and cultivated berries have become very attractive for consumers because of potentially beneficial phytochemicals contained in these fruits. Fruit nutritional quality can be described by standard quality parameters (sugars and organic acids), and the analysis of antioxidant capacity influenced by specific related compounds. The importance of flavonoids and other phenolics have been suggested to play a preventive role in the development of cancer and heart disease. A significant positive correlation observed in this study between total phenolics and total antioxidant capacity indicate the need for the use of wild species in the breeding programs of small fruits, especially strawberry and blackberry, in order to increase their nutritive value and the health benefits.     

Tencel机织物的染整加工及所用染化料

Ｔｅｎｃｅｌ纤维易于原纤化和很高的横向膨润性对染整加工设备选型、工序安排、染化料选用提出了很高的要求，关键的助剂是润滑剂、纤维素酶、柔软剂、树脂整理剂、防原纤化助剂，于是详细讨论了Ｔｅｎｃｅｌ机织物的前处理、初级原纤化、酶处理、染色、二次原纤化和柔性、树脂整理及染化料的应用。     

THIOLS AND DISULPHIDES IN QUIESCENT AND GERMINATING BARLEY GRAINS,BOTH DORMANT AND MATURE

Reduced and oxidised glutathione, cysteine, cystine and traces (too small to quantify) of γ-glutamyl-cysteine and cysteinylglycine were detected, in about the same amounts, in extracts of the embryos of dormant and mature barleys. During micromalting the levels of the thiols and disulphides altered in various ways, but altered in the same ways in dormant and mature samples of grain until germination began. An early decline in the glutathione content of embryos was mirrored by a rise in the amount in degermed grains. Histochemical tests and analyses of isolated tissues showed that in the quiescent grains thiols were concentrated in the embryo (particularly the scutellum) and in the aleurone layer and isolated embryos released thiols into an incubation medium. We conclude that the endogenous thiols and disulphides are not obviously involved in the regulation of dormancy.     

INSTRUMENTAL AND SENSORY TEXTURE ASSESSMENT AND FRACTURE MECHANISMS OF CHEDDAR AND CHESHIRE CHEESES

Textural attributes of Cheddar and Cheshire cheeses, falling within narrow compositional ranges, were assessed by sensory panels, and from force-compression curves generated by compression between two plates, and, for Cheddar cheese only, by penetrometry. Individual sensory measurements did not relate well to any instrumental one, and were better at discriminating between cheeses. Samples of each cheese variety were fractured in different ways and the fracture surfaces were examined in a scanning electron microscope. Fracture surfaces were formed by cutting directly through the matrix, tearing of the matrix along planes high in fat or cracking at grain boundaries. It is suggested that consideration of fracture mechanism may aid the selection and development of useful instrumental methods for texture assessment of cheese.     

AREA- AND PERIMETER-DEPENDENT PROPERTIES AND FAILURE OF MATURE-GREEN AND RED-RIPE TOMATO PERICARP TISSUE

The influence of tomato fruit ripeness on area- and perimeter-dependent properties and dominant failure mechanisms of pericarp tissue were investigated. Tissue discs from mature-green and red-ripe fruit were punctured with a flat-ended cylindrical probe and compressed with a flat plate at a constant rate of deformation. Approximately linear force-deformation curves were obtained to tissue failure by both puncture and flat plate compression, interrupted by a region of pseudoplastic deformation at a relatively low initial bioyield force. Based on estimated area- and perimeter-dependent coefficients and firmness (force/deformation) values, initial bioyielding of tissue appeared to be associated with an abrupt increase in cell-to-cell compaction. Puncture of mature-green tissue led to premature failure induced by shearing or rupture of tissue at the probe perimeter. The contribution to puncture of perimeter-dependent or shear-associated forces and a putative "zone of influence" increased markedly with ripening, while the contribution of area-dependent or compression associated forces generally decreased. A concomitant decrease in failure force and firmness with ripening reflected a general loss of both tissue compression and shear strengths. These results suggested that the dominant mode of tissue failure changed with ripening, from cell relaxation and rupture to cell debonding. The data obtained in this study emphasize the need to exercise caution in the interpretation of force-deformation parameters derived from puncture tests alone.