Aeration trial of farm-stored wheat for the control of insect infestation and quality loss

An aeration trial was conducted in collaboration with the Victorian Department of Agriculture, Australia, to study moisture content and quality changes in farm-stored wheat as a result of moisture uptake from the entering air. Two steel silos each filled with 44 tonnes of Olympic wheat at 33°C were aerated at the rate of 21/s per tonne with an average of 15 h of fan operation per week for 18 months. After 4 months of aeration, the average grain temperature at the centre of the bulk for each month ranged from 11–21°C depending on the season.The average moisture content of one bulk investigated in detail increased from 9.5 to 11.4% (w.b.) after 18 months of storage. Germination and some physical dough properties revealed some deterioration of the wheat near the duct. The rest of the bulk remained practically unaffected during storage and mainly free of storage fungi. Careful assessment of wheat quality before and after storage showed only small changes. The average insect fragment count at outloading was $\text{6}\text{100}\text{g}$ of flour which is considered to be a very low level.Germination and dough extensograph values were found to be, in this investigation, more sensitive indicators of deterioration than other quality tests.     

Susceptibility of Ethiopian wheat varieties to granary weevil and rice weevil infestation at optimal and sub-optimal temperatures

Integrating varietal resistance with temperature manipulation during storage may provide a better option for protection of stored grains and may decrease reliance on the use of synthetic chemicals. The current study was conducted to determine the susceptibility of different varieties of wheat seed to the infestation by the granary weevil, Sitophilus granarius (L.), and rice weevil, Sitophilus oryzae (L.), at optimal (30 °C) and sub-optimal (19 °C) temperatures. Kernels of six wheat varieties namely, Danda'a, Digalu, ET-13-A2, Kakaba, Millennium, and Pavon-76 were examined over a period of 90 d. Significant interactions were detected between wheat varieties and storage temperature for progeny emergence, percentage of insect damaged kernels, grain weight loss, and amount of powder produced per gram of wheat. Kernels of Danda'a, infested with S. oryzae at 30 °C exhibited significantly lower mean progeny counts (13.3 live insects), lower percentage of grain weight loss (4.2%) and insect-damaged kernels (6.4%), and powder production (1.5 mg/g). Kernel weight and hardness index were negatively associated with percentage of insect damaged kernels and grain weight loss. Kernel diameter was positively associated with both of percentage of insect damaged kernels and grain weight loss. Wheat varieties with high Zeleny sedimentation values had lower percentage of insect-damaged kernels and grain weight loss. These results indicated that kernel weight, hardness index, and protein content are predominant factors contributing to wheat resistance against S. granarius and S. oryzae. The varieties Millennium and Danda'a can be considered with other integrated pest management approaches to reduce stored grain losses of wheat in Ethiopia.     

A new method to rapidly detect rusty grain beetle,Cryptolestes ferrugineus (Stephens), in stored grain

Information on insect infestation inside stored grain bulks is required for safe grain storage. A new method to rapidly detect both adults and larvae of Cryptolestes ferrugineus (Stephens) in grain was developed based on the principle of microwave heating and insect behaviour under elevated temperature. The designed apparatus and processing procedure were tested to extract both the adults and larvae inside wheat with 14%, 16% and 18% moisture contents by using a domestic microwave oven (referred to as the microwave method). The recovery percentage of the introduced insects associated with the microwave method was compared with that of the Berlese funnel method (810 cm³ wheat in a funnel under an incandescent light bulb). The microwave method recovered 97.8% of introduced adults, while 90.6% of adults were recovered by the Berlese funnel method. The recovery percentage of the larvae inside marked wheat kernels was 83.3 ± 3.3% with the microwave method and less than 27% with the Berlese funnel method. There was no significant difference in extraction percentage between old and young larvae when the microwave method was used. The moisture content of the treated grain did not significantly influence the extraction percentage of the pest insect. The total processing time of the microwave method was less than 30 min compared to 6 h required for the Berlese funnel method.     

Assessment of quantitative and qualitative losses of stored grains due to insect infestation in Ethiopia

This study was designed to determine the quantitative and qualitative losses of stored grains that arise from insect infestation in three districts of southwestern Ethiopia. One district was selected from each zone based on the production potential of the target crops (maize, sorghum, wheat and fababean). A total of 240 farmers’ stores from all districts were randomly selected. The grain samples used in the present study were stored for 5 different time periods, ranging from 1 to 5 months and from the same farmers’ stores, to determine grain weight loss, insect damage, and nutritional losses. Grain damage showed significant differences over the storage periods across the study districts. A similar trend was observed for weight loss for each of the grains in all districts. The moisture content of the grains decreased along the storage duration. Crude protein and crude fat contents significantly decreased as the storage duration increased in all traditional storage types. Furthermore, the crude fibre and ash contents of the different grain types significantly increased as the storage duration increased in all storage types. These results demonstrated that traditional storage structures have a substantial effect on quantitative and qualitative losses of stored grains. This finding has great implications for food security and hidden nutritional deficits in society. Thus, there is a need to develop and disseminate storage technologies that minimize losses and that are affordable for small farm holders.     

Efficacy of sensor assisted vacuum hermetic storage against chemical fumigated wheat

Alternatives to chemical fumigation, are being explored as the popular fumigants like methyl bromide and phosphine are being phased out for their ozone depleting nature and insect resistance, respectively. Vacuum hermetic storage has potential for storage of agricultural durable commodities without fumigants and can eliminate 99% of insect infestation. In present research, the vacuum hermetic storage was tested in field with assistance of sensors and compared with the conventional phosphine fumigated storage by grain quality assessment and interstitial atmosphere for six months. Relative humidity of the hermetic bags remained below 25%, whereas temperature followed the same pattern as of the ambient. Germination percentage, thousand kernel weight and besatz content did not change significantly (p > 0.05), whereas mould count and moisture content reduced over the storage time compared wheat stored in metal bin.     

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.     

Status of glycemic index of paddy rice grain (Oryza sativa L.) on infestation by storage pest Sitotroga cerealella

The harvested paddy rice grains are normally stored by growers under normal conditions. Paddy rice grains are natural food for storage pests like Sitotroga. cerealella, a major insect that appears during paddy storage. The changes in grain composition due to such insect infestation in relation to human health especially the alteration in their Glycemic Index (GI) value have not been studied so far. The present investigation was aimed at studying the effect of S. cerealella infestation on rice grain quality and glycemic index of stored paddy grains. Five diverse rice genotypes with different quality traits were evaluated for grain quality after S. cerealella infestation. The tolerance to insect and variation of grain quality varied with rice genotype significantly. The glycemic index, glycemic load, total carbohydrate, amylose content and resistant starch were affected to a great extent. The consumption of affected grains may create health issue due to imbalance in nutrition and unhygienic condition. Improper storage of paddy after harvesting and processing results in infestation by pests at a large scale. Thus, the grain quality needs to be evaluated to judge the suitability of affected grain for consumption.     

Comparative utility of hermetic and conventional grain storage bags for smallholder farmers: a meta-analysis

Postharvest management is critical to attaining household food, nutrition, and income security. Hermetic grain storage bags offer an effective pesticide-free way to protect stored grain against fungal and insect infestation. We evaluated articles indexed in the Web of Science that included experiments comparing the storage efficacy of conventional and hermetic storage bags based on grain germination rate, insect infestation, physical damage, mycotoxin contamination, and changes in weight and moisture content. Compared with grain stored in hermetic bags, grain stored in conventional bags lost 3.6-fold more seed viability, contained 42-fold more insects, had 11-fold more physical damage, and lost 23-fold more grain weight, while grain moisture levels were similar for both hermetic and conventional storage bags. Mycotoxin contamination levels were not as frequently assessed. Levels could be low in grain stored in both types of bags, or levels could be low in hermetic bags and significantly higher in conventional bags. The improved properties of grain stored in hermetic bags can increase food security and household income by providing safe storage options for maintaining seed germinability, and for consumption and/or sale when food supplies are high, or when prices are low. Hermetic bags are economically feasible for use by subsistence farmers in Sub-Saharan Africa for grain for household consumption and for carrying-over seed for planting in the next season. Additional studies are needed to verify the mycotoxin contamination results and to determine if there are differences in functional food characteristics, e.g. flavor and cooking properties, that have not been as comprehensively studied. © 2023 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.     

The influence of α-amylase supplementation, γ-irradiation (60Co) as well as long time of storage of wheat grain on flour technological properties

The varieties of winter wheat, Aria and Beta, were studied. The Aria variety was stored for the period of four years. The part of wheat grain from Beta variety was irradiated with γ rays (⁶⁰Co). In extracts from wheat kernels and flour protein content, total α- and β-amylolytic activity as well as α-amylolytic activity were determined. α-amylases of native and fungal origin were added to the flour obtained from samples of stored wheat kernels (Aria), irradiated and non-irradiated (Beta). Consequently native α-amylase activity of flour increased by 25 % and 50% respectively. Extensive technological estimation of grain and flour with amylase supplements was carried out. The study included: sedimentation analysis, falling number test, milling experiment, farinogram and extensogram analyses, measurement of the degree of damaged starch and flour colour, as well as baking experiment. The obtained experimental loaves of bread were tested for their ability to remain fresh. It was found out that the stored grain flour was characterized by the highest α -amylolytic activity and the lowest falling number value, whereas the irradiated grain flour showed the highest degree of starch damage and water absorption. When α-amylase supplementation to doughs wasn't accompanied either by irradiation or storage of grain, it definitely changed their physical properties for the worse. The negative influence of native α-amylases appeared to be less significant than that of fungal α-amylases. The positive influence of α-amylase supplementations, especially of those increasing by 25 % the native α-amylolytic activity of flour on volume, and freshness of loaves of bread was observed.     

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.     

基因、灌溉和贮藏对小麦蛋白质理化特性影响的研究进展

蛋白质理化特性是衡量小麦制品品质的重要指标,其受小麦品种、灌溉条件、籽粒和面粉贮藏时间及温湿度的显著影响。高分子量谷蛋白亚基表达量与蛋白质理化特性正相关。灌溉条件显著影响小麦蛋白质理化特性,适当的节水处理有利于蛋白质积累和麦谷蛋白大聚体大颗粒形成。贮藏时间和温湿度均显著影响小麦蛋白质理化特性;短期贮藏中,贮藏时间与麦谷蛋白大聚体理化特性正相关;随贮藏时间的延长,麦谷蛋白大聚体含量和面团黏弹性逐渐降低;与低温低湿条件相比,高温高湿条件下小麦各指标在贮藏过程中变化幅度大。后期可结合籽粒和面粉贮藏及麦谷蛋白大聚体流变学特性和形貌开展研究,以期为籽粒和面粉贮藏质量,乃至面制品质量控制提供理论依据。     

Detection of External and Internal Insect Infestation in Wheat by Near-Infrared Reflectance Spectroscopy

Near-infrared spectroscopy (NIR) in the reflectance mode was investigated for the rapid, automatic and non-destructive detection of insect stored-grain pests external or internal to wheat kernels. Convincing calibration performance was obtained for external adult Oryzaephilus surinamensis (L) (saw-toothed grain beetle) in unmilled samples including varieties Beaver (soft wheat) and Mercia (hard wheat) at two moisture contents. With this large substrate variability, the method could differentiate between uninfested samples and samples with approximately 270 insects kg⁻¹ or more. Milling made no improvement. Large spectral differences were observed between uninfested kernels and kernels infested internally with Sitophilus granarius (L) (grain weevil) larvae or pupae, arising from both a changed chemical composition and physical structure. Single uninfested and infested kernels were discriminated by their second derivative (d²) spectra. For both external and internal infestation there was substantial evidence that insect protein and/or chitin and moisture were being detected. NIR should be useful as a rapid method of detection.     

Comparative effects of hermetic and traditional storage devices on maize grain: Mycotoxin development,insect infestation and grain quality

A large-scale study was conducted to assess which of the five most accessible hermetic storage devices on the Kenyan market fulfill the needs of smallholder farmers by positively impacting three major areas of concern: insect infestation, grain quality, and mycotoxin (aflatoxin and fumonisin) contamination. Efficacy of two hermetic silos (plastic and metal) and three hermetic bags (PICS, GrainPro's GrainSafe™, and Super Grain) was directly compared to current maize storage in polypropylene (PP) bags under local environmental conditions using representative storage volumes during a 6-month storage period. Impact of maize grain stored at typical (∼15%) and recommended (<13.5%) moisture levels and potential efficacy losses through frequent interruption of the underlying hermetic principals was assessed. Hermetic storage significantly reduced the increase in aflatoxin compared to PP bags regardless of the moisture level of the grain. An <5% per month aflatoxin increase was achieved by three of the five devices tested: Metal silo, PICS and GrainSafe™ bag. A strong correlation between grain moisture, storage time and aflatoxin development was found in PP bags, but not in any of the hermetic devices. The same result was not obtained for fumonisin development in stored maize. The rate of Fumonisin increase was similar in all tested devices, including the polypropylene bags, and conditions. The periodic opening of the hermetic devices had no significant effect on the efficacy of the hermetic devices but the repeated disturbance of the PP bags led to a significant increase in aflatoxin levels. The maize weevil Sitophilus spp. was most commonly found with a total incidence of 72%. Grain storage under hermetic conditions reduced insect infestation, grain weight loss and discoloration. However, maize storage above recommended moisture levels led to a distinct odor development in all hermetic devices but not the PP bags. Hence, proper grain drying is a prerequisite for maize storage in airtight conditions.     

基于GC-IMS技术分析小麦粉储存过程中挥发性物质的变化

研究小麦粉在储藏过程中典型指标的变化规律,基于气相色谱-离子迁移谱（GC-IMS）技术分析小麦粉储藏过程中挥发性有机物的变化,为小麦粉储存期间品质评价提供新的分析方法和参考依据。结果表明：小麦粉中挥发性物质以醇类、醛类、酯类化合物为主;利用GC-IMS的分析结果结合主成分分析、偏最小二乘-判别分析和热图聚类分析可以有效区分不同储藏期样品,小麦粉储藏过程中挥发性物质变化与水分、脂肪酸值和品尝评分值的变化趋势,验证了小麦粉在储藏过程中的挥发性物质变化可以用于储存时间的判断。     

高水分小麦通风干燥过程中加工品质变化规律研究

将刚收获的高水分小麦放置在就仓干燥模拟仓内进行通风干燥,测定小麦粮堆各层水分含量变化,及小麦粗蛋白含量、湿面筋含量、粉质特性、降落值等指标。结果表明：含水量超过20%的小麦在模拟仓中采用纵向通风技术可以在短期内将小麦水分含量降低至安全水分,对其加工品质没有显著不良影响。使用通风技术可有效降低小麦水分含量,但各粮层降水存在一定不均匀性,在实仓干燥中可辅以其他技术予以改善。     

山东省六个主推小麦品种加工品质特性

对山东地区6个小麦品种进行了较系统的品质测定,分析了小麦品种间籽粒品质、面粉品质、面团品质性状及烘焙特性的差异。结果表明,山农12号籽粒和麦粉品质性状较好,面团具有较好的弹性和延伸性;泰麦1号和淄麦12号籽粒硬度、容重较大,面团品质性状佳,烘焙效果好。     

Influence of storage conditions on the quality properties of wheat varieties

Effects on the quality properties in real storage conditions and galvanized steel silos for wheat varieties (cv. Bezostaya and Lancer) in the 180 day storage period were investigated. The wheat quality properties including grain moisture, crude protein, hectoliter weight, thousand grain weight, Zeleny sedimentation, wet gluten, dry gluten, and falling number were monitored in the laboratory in three replicates at regular intervals. From these results, crude protein, hectoliter weight, and thousand grain weight of Bezostaya and Lancer wheat varieties decreased with an increase in storage period. Grain moisture, Zeleny sedimentation, wet gluten, and dry gluten increased with storage period until the first two months and subsequently decreased. However, grain moisture for Lancer wheat increased until the third month of storage, after which it decreased. Falling number increased with increase in storage period.     

高筋小麦粉储藏技术的研究

以高筋小麦粉为研究对象,通过模拟在不同温度(15、25、35℃)、不同储藏方式(充N2、脱氧剂脱氧、真空、对照)下储藏高筋小麦粉,研究了储藏期间高筋小麦粉脂肪酸值、降落数值、湿面筋、面筋指数的变化规律。结果表明:高筋小麦粉的脂肪酸值、降落数值、湿面筋以及面筋指数都能较好地反映出高筋小麦粉储藏品质的变化。总体变化趋势表现为:随着储藏时间的延长,脂肪酸值和降落数值升高,湿面筋含量和面筋指数下降。在储藏期间温度的变化是最主要的影响因素,低温有延缓品质劣变的优点;其次为储藏方式,但相互之间差别不明显;同时发现气调储藏在高温环境中效果较好,所以高筋小麦粉应尽量保存在低温气调储藏条件下。     

Use of response surface methodology to investigate the effects of milling conditions on damaged starch,dough stickiness and chapatti quality

Response surface methodology was used to investigate the influence of three factors namely mill aperture, feed rate and moisture content of wheat grain on the damaged starch content of whole wheat flour from Lokwan wheat cultivar, dough stickiness and chapatti (Indian unleavened flat bread) quality. Each predictor variable was tested at three levels. Aperture was varied as 2, 3 and 4 mm in a stone mill, feed rate as 0.21, 0.63 and 1.05 min for 200 g wheat grains and grain moisture content as 8.6, 14.3 and 20% w/w. Flours containing varying amounts of damaged starch ranging from 6.1% to 26.90% were obtained and these were evaluated for dough stickiness and chapatti quality. Dough stickiness was increased with decreased aperture. With decreased aperture and increased grain moisture content softness of the chapatti was improved.     

Effects of fungal deterioration on grain: nutritional value, toxicity, germination

Moulds or fungi that grow in grains and seeds during storage and transport cause germination decrease, visible mouldiness, discoloration, musty or sour odours, caking, chemical and nutritional changes, reduction in processing quality, and form of mycotoxins. These deteriorative changes affect the grade and price of grain and contribute to customer dissatisfaction when the grain is marketed. The respiration of grain and fungi results in a loss in dry matter as well as the production of heat and moisture which contribute to further spoilage. Net changes in nutritional value and the risk of mycotoxin contamination are difficult to predict because they depend on a complex interaction of factors such as temperature, moisture, storage time, fungal species composition, kind of grain, and previous storage history. Moisture is the most important variable determining the rate of deterioration caused by fungi, with temperature being the second major factor. Problems with deterioration of grain in export shipments are not a recent development. They are related primarily to grain moisture at loading, and also to the extent of previous mould invasion.