The oviposition and development of Sitophilus oryzae (L.) in different high-yielding varieties of wheat

Studies on the oviposition and development of Sitophilus oryzae in high-yielding varieties of wheat (PV-18, Sonora-64, Kalyan Sona, S-308 and S-307) were conducted at all combinations of the three temperatures, 19°C, 25°C and 30°C and four relative humidities, 45, 60, 75 and 90 per cent. Oviposition and development of the weevil were better on larger kernels. The rates of oviposition and development were affected by certain other factors besides the physical nature of the kernel and its bran and endosperm. According to the development index ($\text{log}\text{n}\text{Av}$) and number of eggs deposited, varieties in increasing order of suitability were Sonora-64 > PV-18 > Kalyan Sona > S-308 > S-307. Oviposition and development were best in varieties with the highest moisture content at any level of relative humidity. Oviposition and development were best at 75% r.h. or 15·0–15·5 per cent moisture content in all varieties. Oviposition and development rates were greater at 30°C and slower at 18°C than at 25°C. Of the conditions examined 30°C and 75% r.h. was the best for oviposition and development of S. oryzae.     

An aeration trial of bulk stored peanuts for the control of insect infestation and quality loss

An aeration trial was conducted at Kingaroy, Queensland, Australia, to compare upward flow forced aeration with natural ventilation. Cylindrical concrete bins, each having a capacity of 170 tonnes, filled with bulk unshelled peanuts, were used. The aeration rate was approximately 2.5 l/s per tonne of peanuts with an average of 12 hr of fan operation per week.This resulted in a slight drop of the average peanut temperature (2–6°C) in a period of 9 months. The slight drop is believed to be due to unavailability of suitable inlet air temperatures during aeration.The increase in average moisture content of the aerated bulks was negligible. However, the moisture content of peanuts at the bottom of all bins increased from about 6.5 to 10%, regardless of aeration.Analysis of bulk samples after ten months of storage showed the average infestation level of the aerated bins to be considerably less than the level of the naturally ventilated bins. Free fatty acid content was also higher in ventilated bins than in aerated bins. There were no significant differences in viability and appearance of the kernels.     

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.     

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 moisture content and equilibrium relative humidity of dried fruit—Sultanas

A vacuum oven method is recommended for the determination of the moisture content of sultanas, drying to constant weight at 70°C, and at a pressure of 5 mm Hg or less, for 24 hr. It is shown that accuracy of better than 0·5 per cent cannot be guaranteed and that day to day variation, and oven position variation are encountered. A distillation method, using toluene as the entrainer, over a period of $\text{2}\text{1}\text{2}\text{hr}$, gives satisfactory estimates of moisture content when a ‘rapid’ but less accurate estimate is required. Data are presented for the moisture content/equilibrium relative humidity (e.r.h.) relationship of Turkish sultanas.     

Farm‐Scale Experiments to Compare Infestation and Quality Changes in Malting Barley Stored at Three Moisture Contents

Comparison of changes in temperature, moisture content, infestation and germination were made in six aerated 20 t bins of malting barley. Two were at about 13.5% moisture content, three at about 15.5% moisture content, and one at about 16.5% moisture content. The grain started at between 20–25°C and, during aeration, fell at a rate dependent on the moisture content, damper grain being cooler, presumably due to evaporative cooling. The ‘high’ moisture content grain was often over 5°C cooler at 1m and 2m than the ‘low’ moisture content bins. Moisture uptake at the surface was related to bulk moisture content and trends in mite population changes were related to moisture content. Mite population achieved highest numbers at the grain surface but usually before the moisture content absorption was at its peak. They were commonest in the ‘high’ moisture content bin and least numerous in the ‘low’ moisture content bins. There were no apparent differences between bins in the numbers of insects trapped, for instance they were not less numerous in the coolest ‘high’ moisture content bin. However, the trends of numbers trapped followed a similar pattern in all bins; normally O. surinamensis and S. granarius only began to decline after nine weeks storage in December when temperatures fell below 10°C. Germination loss at the surface of the dampest bin was sufficient to cause rejection of the entire bulk for malting. Micromalting indicated that yield of extract and friability were particularly affected by the changes at the surface of the dampest barley.     

Dough characteristics of wheat flour milled from wheat grains stored in spike form

This study compares the effects of storage form (grain and spike) of wheat as well as grain moisture content (12%, 14% and 16%), storage time (0, 3, 6 and 9 months) and temperature (10, 20 and 30 °C) on rheological (farinograph and extensograph) characteristics of dough obtained from stored wheat. While water absorption, stability and degree of softening of wheat stored in spike form were 61.2%, 15.8 min and 25.9 Brabender unit (BU), these values of wheat stored in grain form were 60.8%, 14.1 and 29.1 BU, respectively. Resistance to extension and dough energy of wheat stored in grain form were significantly higher than those of wheat stored in spike form, while extensibility was significantly lower. Storage in spike form had a positive effect on all farinograph and extensograph characteristics of wheat stored under nonoptimal storage conditions such as high grain moisture content, high temperature and long storage time.     

横向谷冷通风过程的数值模拟研究

基于局部热湿平衡原理和多孔介质传热传质理论,建立了储粮通风过程中粮堆内部流动及热湿耦合传递的数学模型。采用计算流体动力学的方法,对横向谷冷通风时粮堆空气内部流动、热量传递和水分迁移过程进行了数值分析。研究发现,横向通风约72 h,粮仓进风口冷空气平均温度为17.5℃、相对湿度为85%,仓内粮堆一次降温从32.2℃降低到23.6℃,降温幅度为8.6℃。水分从12.2%降到12.0%,降水幅度为0.2%。相对于地上笼垂直通风而言,横向通风时粮堆内部速度分布均匀、温度梯度较小,且具有降温速度快,冷却效率高的特点。     

The influence of photoperiod on the life-cycles of Ephestia calidella (Guenée) and Ephestia figulilella Gregson (Lepidoptera: Phycitidae)

When reared at 30°C 70% r.h. and fed on a diet of wheat-feed, glucose and yeast, some larvae of Ephestia calidella and E. figulilella entered diapause at photoperiods of 13 hr light and less per day. In continuous darkness for 60 days, no E. calidella larvae exhibited diapause, but two E. figulilella larvae showed some delay in development in food infested by psocids. Under a light regime of 13 hr light followed by 11 hr darkness ($\text{13L}\text{11D}$), 45 per cent of E. figulilella but only 3 per cent of E. calidella larvae entered diapause. The critical photoperiod for both species was between $\text{12L}\text{12D}$ and $\text{13L}\text{11D}$. For both species, survival was good in continuous darkness and poor in continuous light. Wherever diapause was detected, it delayed adult emergence by an average of 48 days for E. calidella and 74 days for E. figulilella.When reared at 20°C 70% r.h. in continuous darkness for 140 days, 96 per cent and 91 per cent of E. calidella and E. figulilella larvae, respectively, entered diapause. In neither species was diapause observed at 20°C $\text{16L}\text{8D}$. In E. figulilella diapause did not appear at photoperiods longer than $\text{13L}\text{11D}$ at this temperature.Transfer of larvae which were in diapause after 60 days at 30°C in a $\text{12L}\text{11D}$ photoperiod to one of $\text{16L}\text{8D}$ reduced the range of emergence period for E. calidella by 15 days and for E. figulilella by 75 days, compared to controls left at $\text{12L}\text{12D}$. Mean development periods were shortened by 13 days and 54 days respectively. Insertion of a 30 day cold period at 5°C did not significantly hasten the termination of diapause.Similar effects were obtained when E. calidella larvae entered diapause at $\text{12L}\text{12D}$ and 20°C. In this case, transferring diapause larvae to the longer photoperiod reduced the development period range by more than half that of controls at $\text{12L}\text{12D}$. Mean development period was reduced by 63 days. E. calidella larvae entering diapause at 20°C appeared to possess a more intense diapause than those entering at 30°C.The significance of diapause in these species in relation to their potential as pests is discussed.     

Mycotoxins in cereal grain Part 12. Contamination with ochratoxin A and penicillic acid as indicator of improper storage of cereal grain

Formation of ochratoxin A and penicillic acid in wheat kernels at 6 moisture levels: 15, 18, 21, 24, 27 and 30% at 15 °C has been examined during 4 months of storage. The minimum time for formation of significant amount (0.5–1 mg/kg) of ochratoxin A and penicillic acid (6–8 mg/kg) in stored grain has been found for the various water contents as follows: 18%–16 weeks, 21%–6 weeks, 24% and more — 2 weeks. At 15% of moisture content formation of ochratoxin A and penicillic acid was not observed until 4 months of storage.     

Investigation of sorption isotherms of wheat germ for its effect on lipid oxidation

This research aimed to investigate the oxidation and sorption isotherm properties of wheat germ and to determine monolayer moisture content (m₀) in particular, because it has a limiting effect on lipid oxidation. This research comprised two stages. The first stage was the determination of sorption properties and m₀ at three temperatures (15, 25, and 35°C). The second stage of the research was to investigate lipid oxidation properties of stored wheat germ at two different temperatures (4 and 25°C) and m₀ for 28 days. As a result, it was determined that wheat germ has a Type II sorption isotherm, Halsey is the best fitting sorption equation, and the average m₀ is 4.25 g moisture per 100 g dry matter. Furthermore, the free fatty acid and peroxide value of wheat germ oil increased with increasing storage moisture content and temperature, determined as 12.63% and 5.01 mEqO₂/kg on average, respectively. In conclusion, storage of impermeably packaged wheat germ at low temperature and m₀ content is an applicable method for decreasing rancidity and prolonging shelf-life.     

The effectiveness of fenitrothion and malathion as grain protectants under bulk storage conditions in New South Wales, Australia

Fenitrothion at 2.5, 5.0 and 6.0 ppm was compared with malathion at 12.0 and 18.0 ppm for the protection of bulk wheat in vertical bin silos, and 10 ppm fenitrothion was compared to 18.0 ppm malathion in horizontal bulk depots. In both types of storage the persistence of the insecticides could be correlated with the temperature and moisture content of the grain. Under the conditions of silo storage, both protectants remained effective against Rhyzopertha dominica, Sitophilus granarius and secondary pests for as long as 19 months. Under the more severe conditions of horizontal bulk storage the higher applications were effective for only 6–7 months. Fenitrothion at one half the application rate of malathion appears to give equivalent protection against the deterioration of stored wheat caused by attack from stored product insect pests.     

全麦冷冻面团研究进展

冷冻面团是全麦食品的一种良好载体,可简化生产操作,降低加工难度,加快全麦食品的工业化生产。综述了全麦食品中的膳食纤维对面团及冷冻面团品质的影响,在冷冻和冷藏过程中全麦冷冻面团的发酵特性和流变学特性的变化,以及食品改良剂对全麦冷冻面团的品质改善等研究。通过分析全麦冷冻面团中面筋蛋白、淀粉、发酵特性、流变学特性等在冷冻和冷藏过程中劣变原因,为改善全麦冷冻面团的品质提供理论基础和实践参考。     

Fatty acid composition and oxidation of cowpea (Vigna unguiculata) flour lipid

The lipids extracted from cowpea flour before and after storage at water activities (a_w) of 0·11, 0·33 and 0·75 and at 5, 25 and 40°C for 6 months were examined for their fatty acid composition and oxidation.Linoleic, linolenic and oleic acids, in decreasing order, were the unsaturated fatty acids recorded. The saturated fatty acids were palmitic, stearic and arachidic in decreasing order. The total unsaturated fatty acids concentration was higher than the total saturated fatty acids, with palmitic acid being the single dominant fatty acid.$\text{Saturated}\text{unsaturated}$ fatty acid ratios ($\text{s}\text{u}$ ratio) and lipid conjugated diene absorbance at 233 nm indicated that the a_w of 0.33 and the storage temperature of 5°C were the most effective in mitigating the oxidation of the cowpea lipid.Oxidation rates of the unsaturated fatty acids were related to their levels of unsaturation.     

A systemic approach to qualitative changes in the stored-wheat ecosystem: Prediction of deterioration risks in unsafe storage conditions in relation to relative humidity level, infestation by Sitophilus oryzae (L.), and wheat variety

A multidimensional laboratory trial was carried out to identify the primary causes of changes in quality traits in the stored-grain ecosystem to reveal critical storage condition boundaries that may endanger grain quality retention. Qualitative criteria were followed on grain batches from 3 wheat varieties which were stored for 160 d at temperature of 22-23 °C, at two different relative humidities, and with or without infestation by the rice weevil Sitophilus oryzae, to build a multivariate data matrix. The interactions between biotic deteriorative factors and qualitative trait changes were explored through a principal component analysis (PCA). From the Pearson’s product moment correlation matrix, it was observed that the variables that correlated significantly with insect and fungal species dynamics were: moisture content, hL mass, seed viability, and fat acidity of extracted whole flour. Four factors explained the major part of the variance: storage duration, moisture content, hidden insect infestation density, and fungal contamination level. The rate of increase of the insect population was significantly different between varieties. PCA revealed that the significant difference in qualitative deterioration pattern observed between the three varieties was not related to their hardness but rather to a different relationship between the grain and relative humidity. Germination rate was the first quality factor to decline during the storage period. The technological properties of flour extracted from each variety were not affected before insect population density exceeded 1000 adult insects per kg. The rate of qualitative changes induced by the biotic deterioration factors was processed into a “biodeterioration susceptibility index” (BSI) according to the safe storage time assessed in the present study. This index may be used in IPM approaches to predict the susceptibility of a particular wheat variety to insect and fungal damage during long-term storage.     

Effect of microwave heating of wheat grains on the browning of dough and quality of chapattis

Studies were conducted to evaluate the effect of microwave (900 W, 2450 MHz) heating of wheat grains conditioned to different moisture levels on the activity of polyphenol oxidase (PPO) and subsequent colour changes during storage of wheat dough. The results showed that microwave heating of wheat grains for 80 s decreased the PPO activity significantly ( P  ≤ 0.05) with an increase in moisture level from 12 to 18%. Whole wheat flour milled from microwave treated wheat grains (80 s, 18% MC) had 93.39% less activity of PPO. The dough balls (40 g), pressed and rolled into circular form (150.00 mm diameter and 2.00 mm thickness) and stored at 5–6 °C for 72 h. The colour of flattened circular dough was measured using Hunter Colour Meter and it was found that L -value (lightness) decreased from 64.21 to 60.23 in treated and from 64.79 to 47.93 in control samples after 72 h of storage. The results showed that the microwave heating effectively controlled the enzymatic browning in dough and improved the consumer acceptability of chapattis prepared from the same during refrigerated (5–6 °C) storage for 72 h.     

谷朊粉和小麦淀粉添加量对重组面团冻藏品质的影响

面团的冷冻保存品质无法满足鲜湿面条工业化生产的要求。为了研究面团主要组分（面筋蛋白和淀粉）对面团冷冻品质的影响,以高筋小麦面粉（50%）、谷朊粉和小麦淀粉（不同比例）为原料进行面团重组,-18℃冻藏20 d分析其水分分布、流变特性、糊化特性、凝胶强度、微观结构以及氢键强度,以100%原小麦面粉作为对照组。结果表明,随着谷朊粉:小麦淀粉比例从4:1减小至1:4,冷冻重组面团中的水分分布逐渐由结合水向自由水迁移,弹性模量从125900 Pa降低至73020 Pa;样品的各项糊化参数增大,凝胶硬度也由114.30 g增大到181.39 g。扫描电镜观察发现,谷朊粉:小麦淀粉比例越低越不利于面筋蛋白网络结构的均匀性。添加了谷朊粉和小麦淀粉后,重组面团中的氢键强度均大于对照组,且随着谷朊粉:小麦淀粉比例的减小不断增大。当谷朊粉:小麦淀粉为4:1时,冻藏20 d的重组面团的弹性模量值比对照组高49.95%,有效延缓了面团在冻藏过程中的品质劣变。将淀粉与面筋蛋白进行面团重组可以提高面团的黏弹性,进而有利于其冷冻保存品质。     

Rheological properties of instant fried noodle dough as affected by some ingredients

An experiment was set up to investigate the influence of ingredients such as moisture, gum and starch on the rheological properties of instant fried noodle dough. The noodle dough was formulated using a mixture of wheat flour (100%), 0–0.3% guar gum, 0–7.5% starch and 30–42% moisture. The rheological properties of noodle dough were influenced by the ingredients and their interactions. Increasing moisture content decreased Young's modulus (E) of dough samples. Addition of gum to dough at a lower moisture content of 30% increased E, decreased the energy at break (EB) and increased the storage modulus (G′) values. Interactions of starch and gum influenced changes in the rheological parameters at higher moisture contents. Increasing starch content in noodle dough with a lower gum concentration increased EB to a point beyond which further increase in starch concentration decreased EB. Gum and starch improved the binding and mechanical network in the dough. Insufficient water in the dough apparently reduced cohesion in the dough whereas excess water reduced the functionality of gum and starch. Copyright © 2005 Society of Chemical Industry     

Controlled aeration of rice in bulk

Factors affecting the quality of rice during storage in bulk have been investigated, including environmental requirements for minimising microbial growth on the rice by convective and evaporative cooling. In laboratory tests, mould on Caloro rice was first detected after 1 1/2 months' storage at 25° and 75% R.H., but was evident after only one week on rice stored at 25° and 90% R.H. Limiting conditions for drying (and hence evaporative cooling) of rice during ventilated storage were ascertained from a study of the sorption isotherms, determined in the laboratory which indicated that during the last stage an aerating atmosphere of 25° would require to have a humidity of 75% R.H. or less in order to reduce the moisture content of rice to the desirable final value of 14-15%. Rice with an initial moisture content ranging between 16 and 22% was used during a full-scale aeration trial in which temperatures at various locations in the rice load (520 tons) were continuously recorded. Since these temperatures varied systematically with ambient temperature, heating of rice through microbial activity apparently did not take place during aeration—a fact confirmed when the rice was unloaded from the storage bin at the end of the aeration trial. A specially designed humidity-controlling device was tested during the last 2 1/2 weeks of the major aeration trial and functioned satisfactorily.     

食品添加剂对面团玻璃化转变温度的影响

实现食品的玻璃化贮藏是提高食品质量的有效手段。本研究利用差示扫描量热仪探讨了适用于面团玻璃化转变温度测量的扫描程序、研究了水分含量及若干食品添加剂对面团玻璃化转变温度的影响规律。结果表明,多次扫描法是一种可行的面团玻璃化转变温度的测量方法;水分添加量对面团的玻璃化转变温度有明显影响。在本研究的范围内,面团的玻璃化转变温度随面团水分含量的增加而明显下降。食品添加剂对面团的玻璃化转变温度有显著影响。添加抗坏血酸、海藻糖及明胶时,均可不同程度的使面团的玻璃化转变温度有所升高,这对于在现有储存条件下(-18℃)实现面制品的玻璃化保存,提高速冻面制品的稳定性,改善速冻面制品的质量有重要的应用价值。