Dynamics of the particle moisture distribution during storage of wheat under laboratory and pilot-scale conditions

To predict the storability of grain, detailed information is required on the moisture distribution within the grain bulk since a significant variance can be expected in the moisture content between individual grain kernels during storage. Therefore, it is important to consider and determine the single kernel moisture content distribution. The aim of this work was to investigate mass transfer processes that occur during long-term and intermediate storage of grain. For it, the method of particle moisture distribution analysis by means of the Time Domain Nuclear Magnetic Resonance spectroscopy was used. For this purpose, fundamental laboratory-scale experiments were conducted in small storage containers. As these storage experiments revealed, the width of the particle moisture distribution decreased noticeably when there was enough air available in the container for moisture exchange. Thereafter, the storage experiments were extended to pilot-scale using barrels to store grain for months in the scope of about 90 kg per batch. These experiments were performed without ventilation so as to simulate dead zones of airflow that often occur under industrial-scale flat storage conditions. In the closed barrels, no equalization of the particle moisture content was observed even after eleven months of storage. The knowledge gained from the experiments conducted at the micro and meso levels facilitates the understanding of the mass transfer processes that occur during macro scale storage, which are difficult to examine as an entity.     

Establishing the value of modern seed storage methods for wheat in diverse production ecologies in Nepal

In the developing-country context of Nepal, farmers often incur seed losses of 15–30% due to improper storage. To evaluate the efficacy and costs of modern storage alternatives, experimental trials were set up among ten farmers each in two contrasting ecologies, i.e. Palpa (hills) and Rupandehi (terai plains) districts of Nepal in 2013. Several wheat seed storage options were contrasted including farmer practices (FP) such as reused fertilizer bags, polythene bags, household metal containers, and mud bins. Modern storage methods that were evaluated included plastic bags (with and without pesticide), metal bins, and hermetic ‘SuperGrain bag’ (SGB). Seed quality and losses were assessed after six months of storage (May–October) with parameters such as grain moisture content, insect damage, seed germination, and seedling vigor. The overall quality of seed with FPs was lower in the hills than in the terai plains. Among the treatments, SGBs were more effective in maintaining acceptable seed moisture levels, controlling insect damage (<1%), preserving germination (>90% lab, >65% field), and promoting seedling vigor. Metal bins and plastic bags without pesticide had higher insect damage (7–15%) compared to FP and plastic bags with pesticide (2–5%). In terms of storage costs, SGBs were comparable with the farmers' storage methods ($5–6 per 100 kg seed storage). Our findings demonstrate that SGBs are better at maintaining seed quality and more economical than not only FP but also the other modern storage methods evaluated in this study across production ecologies in Nepal.     

不同储藏温度下油菜种子生活力的基因型差异

以发芽率为指标,研究了40份甘蓝型、白菜型和芥菜型油菜在-20℃、4℃、25℃、37℃、60℃温度储藏3个月、6个月、12个月后种子生活力的变化。结果显示：-20℃和4℃储藏下,不同基因型间种子发芽率变异较小,而25℃、37℃和60℃储藏下,基因型间种子生活力存在明显差异,选择60℃高温储藏不同时间的种子进行生活力鉴定,从甘蓝型、白菜型和芥菜型油菜中均筛选得到耐储藏的基因型。     

Grain storage systems and effects of moisture,temperature and time on grain quality - A review

Global grain production has been increasing every year, which highlights the need for investment, maintenance, and effective management in warehouses. Warehousing is a major bottleneck as it influences the possibility of negotiating for better market prices. In order for profitability to be increased, assurance of product quality for the consumer is necessary. Hence, there is a need for standardization of scientific research and the production chain in this field. The purpose of this bibliographic review is to describe the existing storage systems for grains, steps to be taken for care, and the main studies carried out in this field, to guarantee grains of good quality. The maintenance of the characteristics of the grains after harvest, is essential to guarantee grains of good quality to consumers. However, there are still deficiencies in the field of grain storage, and features of the different systems and conditions to be adopted for each of them are provided in this review.     

腊梅花坯含水量对精油品质及物质组分的影响

本文采用超临界CO₂萃取技术研究腊梅花坯含水量对精油品质及物质组分的影响。结果表明,随着腊梅花坯含水量的降低,精油综合品质发生了较大的变化,表现出先下降后升高再下降的趋势,以腊梅花坯含水量分别在78.3%和28.0%时萃取的精油品质较好。花坯含水量较高（59.9%⁷8.3%）时,萃取精油的主要成分变化较大,随水分含量的降低,萃取精油的物质组分逐渐趋于稳定;在各处理的精油物质组分中,共有的大类物质主要有醇类、酯类、烯烃类、酚类、烷烃类和酮类六类,相对含量较高的成分有:氧化芳樟醇和苯甲醇。花坯含水量为28.0%和44.7%时,物质的种类较多,达到62种;花坯含水量为59.9%时的物质种类较少,为45种。      

水分含量对新鲜干酪贮藏特性的影响

对水分含量不同的4组干酪进行贮藏期水分含量、水分活度、pH、酸价、TBA值测定和感官评定。结果表明:干酪水分含量与水分活度随贮藏期呈递减趋势,并且呈正相关关系;酸价随着贮藏期的延长先增加后减少;pH则相反,呈先下降后上升的趋势;TBA值呈逐渐上升趋势。表明水分含量低的干酪,其耐贮藏性较好。感官特征测定在贮藏的第18d开始,干酪逐渐开始出现腐败特征,水分含量较低的干酪感官评分高。     

Physical properties, molecular structures, and protein quality of texturized whey protein isolate: effect of extrusion moisture content

To explore the complex relationship between processing conditions and functional and nutritional properties of food products containing whey protein isolate (WPI), we investigated the effect of extrusion texturization at various temperatures (50, 75, and 100°C) and varying moisture levels of the feed (20, 30, 40, and 50%) on changes in the composition, molecular structure, and protein quality of the extrudates. Bradford assay methods were used to determine protein solubility of the extruded WPI as a function of changing level of moisture. Protein compositional changes as a function of extrusion conditions were quantitatively characterized and analyzed by sodium dodecyl sulfate-PAGE and reversed-phase-HPLC techniques. We showed that at a given temperature, increasing the extrusion moisture content resulted in a slight increase in the overall protein water solubility (at 50 and 75°C), averaging approximately 5% per 10% increase in moisture content. A reduction in β-lactoglobulin content was observed at 50°C with increasing moisture content, indicative of the sensitive nature of β-lactoglobulin to extrusion treatment, whereas the amount of α-lactalbumin remained unchanged at all moisture contents used at a set temperature. The protein quality of the extruded WPI, determined chemically by available sulfhydryl and primary and secondary amines, remained relatively unchanged as a function of moisture level. Circular dichroism and intrinsic tryptophan fluorescence spectroscopic studies revealed considerable structural changes, both at the secondary structural level and the tertiary contacts as a function of increasing temperature, and higher moisture levels can slightly preserve secondary structures but not the tertiary contacts of the protein molecules. Atomic force microscopy provided direct visualization of the fine difference of the protein particles caused by changing extrusion moisture contents, which is in close agreement with the results obtained using other techniques in this work.     

冷藏对蔬菜中亚硝酸盐及硝酸盐含量的影响

目的 探索冰箱冷藏(4℃)条件下蔬菜中硝酸盐和亚硝酸盐含量随时间的变化,对冷藏食品的安全性进行评价.方法 分别采用重氮偶合分光光度法和麝香草酚分光光度法对生菜、菠菜、油麦菜及苦苣4种常用蔬菜在冷藏条件下其亚硝酸盐及硝酸盐的含量变化进行测定.结果 1～4d内,生菜、苦苣中的亚硝酸盐含量随着时间的延长逐渐增加;菠菜、油麦菜中亚硝酸盐含量分别在第2天和第3天达到最大,之后逐渐降低,而菠菜中亚硝酸盐含量在第4天又出现上升趋势.4种蔬菜中亚硝酸盐含量4d中最大值仅为0.419 4 mg/kg(生菜),均＜4 mg/kg的限量值.苦苣和油麦菜中硝酸盐含量在1～4d内逐渐上升.菠菜中硝酸盐含量第2天达到418.48 mg/kg,之后又降低至20.83 mg/kg.生菜中硝酸盐含量在第3天达到最大值317.26 mg/kg,之后逐渐下降,但均在安全范围内(432 mg/kg).结论 在4℃下冷藏4d后,4种常见蔬菜均可安全食用.可见,冷藏能有效减缓亚硝酸盐和硝酸盐含量的升高.     

Soybean seed storage: Packaging technologies and conditions of storage environments

Artificial refrigeration is sufficient for maintaining the quality of soybean seeds in storage in processing plants, but when lots are distributed to rural producers, they are often kept in natural environments, without temperature or relative humidity control, which decreases their germination rates. This research aimed to evaluate different storage conditions and technological packaging for soybean seeds. The first stage evaluated the quality of soybean seeds stored at different temperatures for up to one year in raffia bags with or without polyethylene inner liners. The second stage evaluated the quality of soybean seeds stored in a natural atmosphere in raffia or laminated packaging, in a modified atmosphere with polyethylene packaging, in a refrigerated atmosphere with raffia or laminated packaging, or in a modified and refrigerated atmosphere with polyethylene packaging. An increase in storage time had a negative influence on the quality of the stored seeds. Storage temperature was the main influence in the reduction in seed physiological quality. Storage of soybean seeds in raffia packaging coated with polyethylene in a natural-temperature environment resulted in seeds retaining similar physical and physiological qualities to those stored under refrigeration. Raffia packaging coated with laminated material maintained the best physical and physiological quality of soybean seeds stored over time. Optimal packaging technology with laminated coating in “big bag” format has replaced the conditioning of storage environments with the maintenance of the quality of soybean seeds over time. The packaging technology is an excellent alternative for the soybean processing units.     

Effects of storage durations at different temperatures on various physiological parameters of einkorn seed (Triticum monucocum L.) germination

In this present study, seed vigor was tested after different storage durations (0, 60, 120, 180 days; maximum 420 days) in air-conditioning cabinets set to various temperatures (4, 10, 20 °C) and free-temperature at room condition. After seven days for each of the storage durations, germination rate (GR), mean germination time (MGT), germination speed (GS), seed vigor index (SVI), shoot and root length (SL, RL), shoot and root dry weight (SDW, RDW), root number (RN), electrical conductivity (EC) and pH for all seed lots were recorded. The average GR at room temperature storage decreased from 86% recorded on the 60th day, to 59% by the end of the 420th day, while germination rate was still around 70% with the seeds stored at 4 °C. The decrease in GS was recorded after the 300th day till the end of 420 days of storage (ranging between 9.8 and 9.4 seed day⁻¹). The lowest SVI was 7.9 at the beginning of storage (day 0) and increased gradually within 60 days of storage for all temperatures tested. Irrespective of storage duration, the SL and RN showed the highest overall mean of 10.7 cm and 4.8 root for the seeds stored at 4 °C. EC sharply decreased overall to a mean of 18.9 μScm⁻¹ g⁻¹ for all temperatures within the first 60 days of storage. The highest correlation (r = 0.937) was determined between GS and MGT. This study provides a new insight to the farmers for better understanding that concerns practical implications of einkorn farming as follows: storage at 4 °C is best way of the maintanence of highest seed vigor. For the storage duration regardless of the temperatures, it can be kept minimum 60 days, since the seed deterioration can be effective after 180 days of storage depending on storage temperature.     

Investigation on moisture migration,microstructure and quality changes of fresh-cut apple during storage

Moisture migration of fresh-cut apple during 4 °C storage was monitored by low-field nuclear magnetic resonance (LF-NMR) and magnetic resonance imaging (MRI). Three water components were identified in apple tissue by LF-NMR T₂ relaxation, corresponding to water in cell wall, cytoplasm and vacuole. The relaxation results also revealed that the moisture migrated from the vacuole to cytoplasm and the mobility of water in vacuole decreased with the extension of storage time. T₂ weighted images of MRI indicated that high density of water appeared at the edge of the fresh-cut apple in the later stage of storage. Breakdown of cell walls and intracellular network were observed by cryo scanning electron microscope (cryo-SEM). Moreover, storage process also led to the decrease in moisture content, browning and softening of fresh-cut apple. In addition, good prediction models have been developed for quality indicators using partial least squares regression based on Carr–Purcell–Meiboom–Gill decay data.     

Textural modification of soya bean/corn extrudates as affected by moisture content, screw speed and soya bean concentration

A Clextral BP‐10 (type BC45) co‐rotating twin‐screw extruder was used for texture modification of extrudates. Dry materials were mixed in a mixer for 15 min at low speed before extrusion. Moisture content 21–23% and addition of soya bean flour (0–40%) showed significant influences on the texture of the extrudates. Addition of soya bean flour in the range from 0 to 40% increased the diametrical expansion ratio (P < 0.01), decreased the hardness (P < 0.01) and modifies specific volume and chewing behaviours of the extrudates. Increasing moisture content in the range from 21 to 23%, however, significantly decreased specific volume (P < 0.01), and increases hardness (P < 0.01) of the extrudates. The hardness and crispness of the extrudates at fracturability of 110 g were graded higher than 6.0 by 30 and 27 of 34 consumer panelists, respectively. Consumer purchase intent showed the highest score of 5.5 in a 9‐point hedonic scale when sample fracturability was at 110 g.     

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。     

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.     

Assessing mineral composition and morpho-physiological properties of de-hulled einkorn wheat during storage at different moisture levels

In this study were investigated the effects of different moisture levels (4.8, 9.5, 13, 16.7 and 20%, w.b.) during the storage at 10 °C for three months on some mineral compositions and morpho-physiological properties as dimensional (length, width, thickness, arithmetic mean diameter, geometric mean diameter, surface area and volume, sphericity), gravimetric (thousand grain weight, bulk and true densities) and the seed (colour measurement and electrical conductivity) of de-hulled einkorn wheat seeds. Mineral composition of wheat seeds changed with increasing moisture level. In particular, decreases in mineral composition were observed above 16.7% moisture level. Dimensional properties showed increases depending on increased moisture level. It was found that thousand grain weight and true density values increased with increase in moisture level. However, bulk density values were found to decrease with increase in moisture level. The seed colour properties as L*, a*, b*, Chroma, hue angle and Browning index did not change statistically at the end of three months storage with increase at moisture level. The results showed that mineral compositions and functional properties of seeds at moisture level of 9.5% is more suitable than other moisture levels. As a result, high moisture levels during storage can cause degradation of seed quality.     

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.     

稻谷及其加工产品平衡水分研究进展

综述了稻谷及其加工产品的平衡水分测定方法、吸湿平衡时间、等温线拟合方程以及平衡水分数据影响因素,以促进我国杂交稻谷、转基因稻谷、地方特色稻谷的吸湿特性分析。     

高温储藏玉米品质变化研究

以郑单958玉米为原料,进行鼓风干燥和调质处理,将水分含量分别调为为14.5%、11.7%、9.9%和7.8%,在35℃下密闭储藏,研究在储藏过程中玉米生活力、电导率、过氧化氢酶活动度、脂肪酸值和品尝评分值的变化,探讨高温储藏玉米的水分含量与其储藏品质变化的规律。结果表明:在35℃条件下,水分含量为14.5%的玉米的生活力、过氧化氢酶活动度和品尝评分值降幅大,分别为100%、90.4 mg H2O2/g和42.1分;水分含量为7.8%的玉米的电导率、脂肪酸值增幅最小,分别为10.84μS·cm-1·g-1和12.8 mg KOH/100 g。     

糙米储藏水分对糊化特性的影响

对13.5%、14.5%、15.5%、16.5%水分条件下储藏的糙米进行定期的RVA测定,糙米放入温度设定为25℃的恒温箱中储藏,储藏时间为6个月,每30d检测一次。结果表明：不同水分储藏样品的峰值粘度随着储藏时间延长不断增加,储藏水分越高,峰值粘度上升越快;水分、时间对峰值粘度影响极显著（p〈0.01）;峰值粘度与储藏时间、水分呈极显著二元线性关系。储藏样品的最低粘度随着储藏时间延长不断增加,水分含量越高最低粘度越高;水分、时间影响极显著;最低粘度与储藏时间、水分呈极显著二元线性关系。不同水分储藏样品的崩解值随着储藏时间延长变化不同;水分、时间影响显著性分别为0.029、0.000;回归方程显示,低水分储藏崩解值随着储藏时间延长而升高,高水分储藏崩解值与时间则成显著一元二次方程的关系。水分、时间对最终粘度影响显著性为0.000;最终粘度随时间、水分变化经曲线拟合呈显著二元线性关系,回归方程显著。储藏期间,糙米回生值随时间延长显著上升,储藏后期趋于下降;方差分析显示时间对回生值影响极显著,水分影响不显著,不同水分样品与储藏时间均呈极显著一元二次方程关系。含水率越高,糙米食味品质保持越好。