稻谷霉变程度与敏感品质变化关系研究

将水分为23%、21%、19%和17%的稻谷置于模拟仓中储藏,检测其在储藏过程中霉菌菌落总数、色泽、脂肪酸值、黄粒米、丙二醛和发芽率等品质指标的变化,以期找出稻谷霉变敏感品质指标及其与稻谷霉变程度之间的关系。     

不同储藏条件下稻谷霉菌区系演替的研究

研究了不同储藏条件下稻谷霉菌区系演替及品质变化.结果表明,储藏温度、水分对稻谷霉菌区系演替有重要影响.储藏温度、水分越高,稻谷霉茵量增加越快,也越容易发生霉变,而且曲霉是优势菌.稻谷霉菌量与是否发生霉变及霉变的程度有关,霉菌量在104 cfu/g以下,稻谷处于安全储藏状态,达到105cfu/g时开始发生霉变,超过106 cfu/g时霉变已经相当严重.霉菌的活动最终将影响储藏稻谷的品质,其值变化与霉菌演替有明显的相关性.本研究对利用生态条件控制稻谷中霉菌生长及利用霉菌指标判定稻谷的储藏稳定性,具有重要的现实意义.     

两种储藏方式对三种原粮储藏品质的影响

研究了充氮气调储藏和常规储藏方式下,在不同温度条件下储藏的小麦、玉米和稻谷的储藏品质随储藏时间的变化规律.结果表明:在低温条件下,两种储藏方式下的粮食品质变化相近,但在高温下充氮气调储藏能较好地保持小麦、玉米和稻谷的储藏品质,比常规储藏的各项指标变化都要缓慢些.由于低温储粮费用较低,在生产中应首推低温储粮.当无法满足低温条件时,粮企可以推广采用充氮气调储藏技术.     

高水分小麦发芽率和霉菌活动规律的相关性研究

粮食储藏过程中品质变化主要受到微生物活动的影响,本课题模拟自然储粮条件,将水分为14.5%、15.5%、16.5%、17.5%的小麦贮藏在4、12、22、32℃的生化培养箱,研究其霉菌的活动规律和小麦发芽率的变化。结果表明：温度和水分对贮藏过程中小麦内外霉菌总数变化有显著影响,随温度升高,水分含量增大,贮藏过程中霉菌数量增多,小麦发芽率降低,安全贮藏期缩短。水分含量为14.5%的小麦在低温条件下贮藏安全,32℃时,储藏期不超过25d;水分含量为17.5%的小麦在低温条件下储藏不超过一月,在32℃时不超过一周。水分含量介于14.5%～17.5%之间的小麦安全贮藏期介于这两种水分的小麦的安全期之间。     

优质稻谷准低温储藏与常温储藏品质变化的比较研究

本文研究了优质稻谷在准低温储藏条件下的品质变化,并与常温储藏的品质变化做对比,以期为优质稻谷准低温储藏下的储备周期提供依据。将两种优质稻谷黄华占和两优放入实验模拟仓中储藏,控制环境温度20℃以下,以常温储藏作为对照。每两个月取样对其色泽、气味、脂肪酸值、品尝评分值、黄粒米含量、直链淀粉含量、出糙率、整精米率、过氧化氢酶活动度、发芽率等储藏品质指标、质量指标、加工品质指标、生理品质指标以及糊化特性和质构特性进行测定和分析。结果表明,低温储藏较常温储藏更能延缓优质稻谷品质的劣变,根据GB/T 20569《稻谷储存品质判定规则》,建议准低温储藏的优质稻谷的储备周期不超过18个月。     

高筋小麦储藏品质变化的研究

研究选用郑麦366和西农979两种高筋小麦为研究对象,对小麦进行微波灭活,调节其生活力分别为0%、40%和90%,将其在35℃条件下恒温储藏,通过研究其在储藏过程中的发芽率、电导率、过氧化氢酶、湿面筋和糊化特性的变化,探讨小麦品质变化与其生活力之间的关系。为研究高筋小麦的储藏特性打下了一定的基础。结果表明:储藏过程中生活力越高的小麦其发芽率、湿面筋含量和过氧化氢酶活动度降低幅度越大;生活力越小的小麦电导率升高幅度越小;生活力为40%的小麦的峰值粘度、最终粘度和回生值变化的最多,衰减值变化最少。     

偏高水分粳稻谷的低温储藏试验研究

为探究偏高水分粳稻谷低温储藏中的安全性和品质变化规律，在模拟低温环境(温度15℃)下对偏高水分粳稻谷(15.3%)储藏2.5年，监测了储藏期间稻谷霉菌数量、质量指标和储存指标的变化，并以常规水分(14.3%)的粳稻谷作对照进行了比较。结果表明，偏高水分粳稻谷在整个储藏期霉菌数量均低于105 cfu/g，未出现霉变现象。储藏期间，偏高水分和常规水分粳稻谷在质量指标和储存指标上的变化规律基本一致，但变化幅度略有差异。储藏结束时，偏高水分粳稻谷仍保持良好的品质，水分含量为14.2%，出糙率为80.2%，整精米率为66.8%，黄粒米含量为0.6%，脂肪酸值为23.2 mg/100 g，品尝评分值为77.2。     

不同储藏温、湿度对稻谷霉菌生长的影响及生长预测模型的建立

实验以粮仓中安全水分稻谷为研究对象,探究稻谷在不同储藏温、湿度中的霉菌生长规律,采用Logistic方程拟合稻谷霉菌在不同储藏条件下的生长动力学模型,并对模型的适用性进行评价。结果显示,在20℃及以下,霉菌数量增长缓慢,稻谷处于安全状态;25℃时,43%和75%的湿度为安全储藏条件;30℃时,仅43%的湿度为安全储藏条件;40℃时稻谷霉菌数量变化较小。Logistic方程所拟合出的各个储藏条件中霉菌生长方程的决定系数R~2为0.987±0.017,适用于描述稻谷中霉菌的生长曲线。结合B_f和A_f值,同一温度下,环境相对湿度越高,模型的准确性越低;在10～30℃范围内,随着温度的升高,模型准确性下降。     

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。     

储藏温度对稻谷微生物和脂肪酸值的影响研究

通过模拟储藏,研究了高湿(85%)条件下温度对稻谷微生物区系和脂肪酸值的影响。结果表明:在85%湿度条件下,随着储藏时间的延长,霉菌量和脂肪酸值呈增加的趋势,细菌量呈先增加后减少趋势。方差分析得出储藏温度、时间对稻谷微生物区系和脂肪酸值有显著影响,相关性分析表明霉菌量、脂肪酸值与储藏温度和时间呈显著二元线性关系,而细菌量与储藏温度和时间呈极显著的二元二次曲线关系。进一步的研究表明稻谷脂肪酸值与霉菌量、温度呈极显著的二元线性关系,脂肪酸值随着霉菌量的增加和储藏温度的升高而逐渐增高。     

不同花生品种储藏期间霉菌活动差异性初探

研究了三种常见花生品种在25℃,RH 80%-85%条件下储藏期间的吸湿特性、所含霉菌数量、种群、代谢活性的差异及花生脂肪酸值含量的变化.结果表明:花生储藏期间霉菌带菌量变化、霉菌在花生中代谢活动强度的变化均与花生的吸湿特性有关,其中花育16品种吸湿性最强、带菌量增速最快、代谢活性最高.花生品种在这些特性上的差异与花生颗粒形状、大小等物理性状无关,而与花生品种的蛋白质、脂肪含量数据相一致.容易受到霉菌侵害的花生品种具有高蛋白质、低脂肪含量的特征.     

圆球导热法测定粮食导热系数研究

采用圆球导热法测定了稻谷、小麦、玉米和大豆的导热系数,并对稳态时间、装样均匀性和水分迁移等影响试验准确性的因素进行了分析.结果表明,该方法测定粮食导热系数的稳定时间至少需要8～10h,通过内外球壁多个热电偶的电势差能确保装样均匀,水分含量分别为10.9%、10.1%、11.0%、6.9%的稻谷、小麦、玉米和大豆的导热系数分别为0.105 4、0.141 8、0.136 2、0.127 4 W/(m·℃),水分迁移对低水分粮食导热系数测定结果的影响可以忽略.     

Adhesion of diatomaceous earth dusts on wheat and corn kernels

Insect infestations are a major threat to the quality of stored grain. One method of insect control is to apply diatomaceous earth (DE), a non-chemical, inert dust that is composed of the ossified remains of diatoms. Diatomaceous Earth kills insects via abrasion and desiccation when the insect is exposed to a sufficient quantity of DE from contact on the grain surface. Therefore, good dust adhesion is desirable to ensure that the DE will come in contact with insects in sufficient quantity to provide the insect control expected. This study considered the adhesion ratio of three types of DE, Celite, Dryacide, and Diafil, on wheat and corn kernels. All three types of DE adhered better to wheat than to corn, and to higher moisture grain than lower moisture grain, and moisture content affected the adhesion on corn more than wheat. Dryacide had the lowest adhesion of the three DE tested at each condition. Dryacide's adhesion was significantly lower than at least one other DE in each test and was lower than both other DE for 12% moisture corn and 15% moisture wheat. Celite had the highest adhesion measured in each trial except for 15% moisture corn but was only significantly higher than Diafil for 12% moisture wheat. Additionally, higher surface roughness correlated with higher adhesion percentages, indicating that rougher diatomaceous earth formulations will be better at adhering to grain particles.     

Safe storage guidelines for durum wheat

Storage conditions determine the safe storage period for any grain. Safe storage guidelines for durum wheat have not been developed, despite the fact that it is more susceptible to spoilage than other wheat classes. The rates of deterioration of durum wheat samples with 15, 16, 17, 18, 19 and 20% initial moisture content (wet basis) stored at 10, 20, 30 and 40 °C for 12 wk were studied. The grain deterioration parameters including seed germination, moisture content, appearance of visible mould, invisible microflora, free fatty acid value (FAV), and ochratoxin production were monitored at regular intervals. From these results, safe storage guidelines for durum wheat were developed with respect to the moisture content and storage temperature. Germination rates of the samples decreased with an increase in moisture content, temperature and storage period. Visible mould was found in all high moisture samples (17, 18, 19 and 20%) stored at high temperatures. FAV of the samples increased with moisture content and storage time.     

A comparison of the functional characteristics of wheat stored as grain with wheat stored in spike form

In this study, wheat grain and wheat spike with 12%, 14% and 16% moisture content were stored at 10, 20 and 30 °C for 0, 3, 6 and 9 months. After storage, wheat samples were investigated for hectolitre weight, gluten content, Zeleny sedimentation volume, enzyme activity, acidity, phytic acid and L colour value. Storage of wheat at different storage forms (spike and grain) and storage conditions showed considerable changes in grain quality. In general, the storage period of 3 months positively affected wheat quality. However, hectolitre weight, gluten, Zeleny sedimentation, enzyme activity, acidity and colour of wheat got worse at storage periods beyond 3 months. Hectolitre weight, wet and dry gluten, Zeleny sedimentation, phytic acid content and L Colour value of wheat stored in both spike and grain form significantly decreased during storage. However, the increase in grain moisture content, storage time and temperature resulted in significant increase in total titratable acidity and falling number values of wheat. Falling Number and phytic acid values of wheat stored in spike form were generally lower than wheat stored in grain form. Storage in spike form had a positive effect on especially wet gluten content of wheat stored at non-optimal storage conditions such as high grain moisture content and high temperature. Wet gluten of wheat stored in spike form was higher than that of wheat stored grain form after storage at 30 °C for 6 and 9 months. Wheat stored in spike form is more resistant than wheat stored in grain form against adverse storage conditions such as high moisture content and temperature and longer storage time.     

储粮环境中米象发生与CO2含量变化的关系研究

为阐明储粮环境中害虫发生与CO_2气体含量变化的关系,研究不同含水量的小麦感染不同虫口密度(0、2、5、10、20、30头/kg)米象后储藏环境中CO_2气体体积分数变化的情况。结果表明:对于含水量相同的储藏小麦,储藏环境中CO_2气体体积分数随虫口密度的增加和储藏时间的延长而显著增加。对于含水量12%的小麦,初始感染虫口密度为30头/kg的储粮环境中CO_2气体体积分数最初为0.413%,在第30天达到最大值为14.777%。对于含水量14%的小麦,初始感染虫口密度为30头/kg的储粮环境中CO_2气体体积分数最初为0.720%,在第15天达到最大值为17.197%。本研究结果为今后通过检测CO_2体积分数变化来监测粮堆中虫害发生情况提供了可靠信息。     

Safe storage time of high moisture wheat

Deterioration rates were determined for 15-19% moisture content (m.c., wet basis) wheat (Triticum aestivum L. cv. 'Barrie') stored at constant temperatures or with a step decrease in storage temperatures. Deterioration rates were determined by measuring germination capacity of the grain and respiration rates of grain and microorganisms. Safe storage time was defined as the time for germination to decrease to 90%. Safe storage times of 19% m.c. wheat stored at constant temperatures ranged from 2.5 d at 30 and 35 degrees C to 37 d at 10 degrees C. Deterioration rates of 19% m.c. wheat stored with a step decrease in storage temperatures (35-25, 30-20, 25-20, and 20-15 degrees C) were determined and safe storage times were satisfactorily predicted. Safe storage times of 17% m.c. wheat were 5, 7, and 15 d at 35, 30, and 25 degrees C, respectively. Respiration rates and germination percentages of 15 and 16% m.c. wheat stored at 25 degrees C remained constant for 70 d. The respiration rates of 17-19% m.c. wheat at 25 degrees C increased while the germination percentages decreased with storage time. Germination dropped from 98 to 92-89% when the dry matter losses were about 0.05% and visible mould occurred when the dry matter losses were about 0.1% in 17-19% m.c. wheat. Safe storage times of 17% m.c. wheat stored at 35-25 degrees C were compared with those determined in similar previous work with cultivars 'Domain' and 'Katepwa'. 'Domain' had the longest and 'Barrie' had the shortest storage times.     

不同通风方向对稻谷降水效果影响的数值模拟研究

基于数值模拟方法,对高水分稻谷的就仓降水通风实验工况进行了数值模拟仿真,分析了在垂直机械通风过程中粮食温度和水分的变化规律,对实验数据与计算机模拟结果进行了对比分析。同时,探究了垂直向上和垂直向下通风时的降水效果。研究发现,数值模拟方法可以有效和形象地反映通风过程中粮堆内部的变化规律,在其他条件相同时,沿着粮堆温度梯度方向通风,降水效果更加明显。本研究对粮库的储粮通风操作具有一定的指导意义。     

MICROBIOLOGICAL QUALITY OF WHEAT STORED UNDER DIFFERENT CONDITIONS IN TURKEY

Four different types of wheat storage systems are widely used in the Marmara region. The existing storage conditions were studied and changes in the microbiological quality of the stored wheat under these conditions were assessed.
Depending on the external conditions, ambient temperatures and relative humidities in the stores were 17–26°C and 50–65% RH during summer and 3–10°C and 62–83% RH during winter, respectively. The low relative humidity level during harvesting and subsequent storage was adequate for obtaining low levels of moisture content and water activity in the produci for safe storage. The increase in relative humidity of the air during winter months did not affect the moisture content of the product considerably and the low temperature prevented mold growth. Therefore, all of the four different storage facilities were suitable for safe storage of grain for a period of one year without significant losses in quality due to microbiological load.     

Pecan quality after harvesting and moulding of different varieties store at high relative humidity

Pecan nuts stored in their husks may be subjected to rapid mould deterioration. A study was designed to determine quality characteristics of pecan stored for 7 days before shelling. In addition, the moisture absorption of dry pecans and the increase in mould population of three varieties (Delmas, Moneymaker and Choctaw) stored under controlled conditions of 26 ± 1°C and 85% RH were investigated.
When pecan nuts with husks were stored for 7 days in metal bins soon after harvesting, temperatures inside the bulk rose from 24 to 33°C. However, no notable increase in free fatty acids or in peroxide value of the nutmeals was recorded.
The moisture content of pecan meat influenced fungal infestation: e.g. the moisture content of variety Moneymaker increased rapidly during storage and the final fungal count on this variety was relatively higher than other varieties. The increase in both parameters in Delmas was slower and a smaller fungal population was recorded at the end of the trial.