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.     

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.     

Effect of temperature and fruit-moisture content on discolouration of dried, sulphured Bon Chretien pears during storage

Summary Discolouration of Bon Chretien pears which had been treated with sulphur dioxide and which had moisture contents of either 16, 18 or 20%, was monitored during storage at 4, 7, 10 and 20 °C. Colour was quantified in terms of CIE L*, a*, b*, hue and chroma. L* was used to predict quality retention. Discolouration was categorized as a decrease in all colour parameters, except a* which increased with storage. Measurement of L* showed that only fruit at 16% moisture content and stored at T ≤ 10 °C retained their original colour. The rate of change in overall colour was observed in the following order at 20 °C, 20% > 18 > 16% moisture content. Fruit with 18 and 20% moisture content could be stored at 10 °C for at least 140 weeks without changing their quality grading. Storage at 20 °C shortened this period to 60 and 27 weeks for fruit at 18 and 20% moisture content, respectively.     

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.     

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.     

Modelling biological efficacy decrease and rate of degradation of chlorpyrifos-methyl on wheat stored under controlled conditions

Insecticide residue degradation and pest survival were observed in wheat treated with a low dose of chlorpyrifos-methyl. Treated wheat was stored in small batches at three controlled temperatures and two levels of moisture content of grain, in equilibrium with r.h. in order to stabilise the water activity in the grain during a storage period of 126 d after insecticide application. Every 3 weeks, samples were taken from treated and untreated control grain in each storage condition. Chlorpyrifos-methyl residues declined regularly with time of storage and an exponential negative regression was fitted with high correlation coefficients in most situations of storage temperature and grain water activity (Aw). A multivariate model to show the respective influence of controlled variables involved in the model of residues breakdown (time, Aw, and temperature) was built up through a multiple regression. This model showed the respective importance of the water activity of grain kernels, temperature and formulation of chlorpyrifos-methyl and their combinations on the decline of residues. Simultaneously, the effectiveness of the residues was checked through bioassays with two target species: Sitophilus oryzae and Tribolium castaneum. Taking into account the intentionally low initial applied dose of chlorpyrifos-methyl, the period after application achieving complete kill of the two test insects was rather short and did not exceed 105 d for S. oryzae in the best conditions for control, i.e. low moisture content and temperature. For high Aw (0.8) and storage temperature 30°C, T. castaneum was effectively controlled (more than 95% kill) only on the day after the treatment, survival occurring at the next test date 21 d after the application. High moisture content and temperature and their interactions were the main variables influencing the decrease in the biological effectiveness with time. The concentration threshold for insect survival was slightly below 1 ppm chlorpyrifos-methyl and was influenced by storage and grain conditions. Implications of these findings on storage pest management practices and on the ability to predict the period of biological effectiveness of residues of chlorpyrifos-methyl are discussed.     

Effect of moisture content, storage temperature and storage period on colour, ascorbic acid, lycopene and total flavonoids of dried tomato halves

Dried tomato halves with three storage moisture contents [18%, 24% and 30%, wet basis (wb)], packed in glass jar, plastic container and polyethylene bag were stored in room and cool-chamber environments for 5 months. During storage period average room and cool-chamber temperatures were 20 ± 4 and 5 ± 1 °C respectively. Changes of colour, ascorbic acid, lycopene, total flavonoids and moisture contents were monitored 1-month interval. Significantly higher losses of colour, ascorbic acid, lycopene and total flavonoids were found for room environment than those of cool chamber. A set of regression equations had been developed for colour, ascorbic acid, lycopene and total flavonoids as a function of storage time. No visible microorganisms were detected in the samples during the storage period. Dried tomato with ≤24% (wb) moisture content may be recommended to store in cool chamber (5 °C) and ≤18% (wb) to store in room environment (20 °C) both to be packed in glass jar.     

Furosine content, loss of o-phthaldiadehyde reactivity, fluorescence and colour in stored enteral formulas

Heat effects induced during the storage of enteral formula under laboratory and industrial conditions were evaluated using the following indicators: furosine; loss of available amino groups, measured by decrease in o-phthaldialdehyde (OPA) reactivity; fluorescence associated with the Maillard reaction (345 nm excitation, 415 nm emission); and colour (absorbance at 420 nm). The storage of formulas A and B (with different protein content) at 4, 20 and 30°C during 12, 24 and 36 weeks produced an increase in furosine values. Under industrial storage conditions at 55°C for between 1 and 12 weeks the behaviour of furosine differed between the two types of formulas. In Formula A (lesser protein content), there was a decrease in furosine level after the third week, whereas in formula B (greater protein content) a decrease was observed after the eighth week.
The loss of OPA reactivity reached 18% and 22%, respectively, for formula B and formula A stored at 30°C for 36 weeks. In adverse storage conditions (55°C), the loss of OPA reactivity reached 50%.
Fluorescence intensity (FI) and absorbance at 420 nm increased at all time/temperatures assayed. It reached values of 22.5 and 27.5 for FI and 0.161 and 0.173 for A₄₂₀, respectively, for formula A and B, stored for 36 weeks at 30°C.
Furosine, loss of OPA reactivity, fluorescence intensity and colour are useful indicators of nonenzymatic browning during storage of enteral formulas.     

Extension of shelf-life of whole-wheat flour by gamma radiation

The effect of low-dose gamma irradiation (0.25–1.00 kGy) on pre-packed whole-wheat flour (atta) was assessed in terms of physico-chemical properties, nutritional quality, chapati-making quality and sensory attributes. Semi-pilot scale storage studies on irradiated pre-packed whole-wheat flour revealed that there was no adverse effect of irradiation and storage up to 6 months of whole-wheat flour treated at doses up to 1.00 kGy on total proteins, fat, carbohydrates, vitamin B₁ and B₂ content, colour index, sedimentation value, dough properties, total bacterial and mould count. Storage of wheat flour resulted in slight increase in moisture, free fatty acids, damaged starch, reducing sugars and slight decrease in gelatinization viscosity.
However, irradiation as such had no effect on any of these parameters. Irradiation at 0.25 kGy was sufficient to extend the shelf-life of atta up to 6 months without any significant change in the nutritional, functional attributes. Chapaties made from irradiated atta (0.25 kGy) were preferred even after 6 months storage, compared with the control.     

GLUTEN QUALITY PREDICTION AND CORRELATION STUDIES IN SPRING WHEATS

ABSTRACT

Gluten, “cohesive, viscoelastic, proteinaceous material prepared as a by‐product of the starch isolation from wheat flour” and the storage and dough‐forming protein of wheat flour, is the key to the unique ability of wheat to suit the production of leavened products. Wet gluten was only affected by wheat varieties, while dry gluten was affected by wheat varieties, crop years and their interaction. The wet and dry gluten ranged 8.0–43.13% and 2.58–14.55%, respectively, and were positively correlated with Zeleny value, sodium dodecyl sulfate sedimentation value and falling number. The gluten content was higher in Pavon, SA 42 and Faisalabad 85, while Zeleny value was higher in GA 02 and C 518, resulting in better gluten quality. Zeleny value was negatively correlated with crude protein content (r = –0.1857*). The lowest amount of wet and dry gluten was detected in Triticale and durum wheats as compared to common wheats. Zeleny value and sedimentation value may be used as indicators of gluten content and quality while working on wheats. The information thus collected will be valuable for cereal chemists and wheat breeders for improvements in their future breeding programs.

PRACTICAL APPLICATIONS

This research work will be a breakthrough and helpful for wheat breeders, growers, millers and bakers for their intended uses as every consumer demand specific wheat quality characteristics for their end products.

     

Storage conditions affect quality of noodles with added soy flour and sweet potato

Summary Noodles were prepared from a formulation in which a portion of the flour was replaced with 10% defatted soy flour and sweet potato as 10% flour or 15% puree. Dried noodles were packaged in plastic bags under partial vacuum or air and stored at 4.4 °C or 22–30 °C for 6 months. Colour, β-carotene and sensory characteristics were analyzed at 2-month intervals. Packaging atmosphere had minor effects on colour. Stored noodles became lighter and yellower, and β-carotene decreased, with all changes being greater at 22–30 °C. Storage conditions influenced acceptability scores minimally. Noodles were stored successfully under air with greater quality retention with 4.4 °C storage.     

Quality and textural behaviour of par-baked and rebaked cake during prolonged storage

The effect of par-baking and refrigerator storage on the quality of cake was investigated. Quality evaluation of rebaked cakes was performed by using physical, chemical and instrumental texture profile analysis. Cakes were par-baked for 15, 20 and 25 min at 175 °C and then they were stored at refrigerator temperature (4 °C) for 30, 60 and 90 days, wrapped with two polyethylene bags. After storage, par-baked cakes were rebaked at 175 °C and were subjected to analysis. Par-baking and intermediate storage time had a significant effect on baking loss, crumb moisture content, colour, symmetry index and textural properties of cake. The increase in the par-baking time led to a decrease in the baking loss and an increase in the moisture content of cake. Specific volume, moisture content, L colour value and symmetry index significantly decreased with increasing intermediate storage time, while baking loss significantly increased. However, regarding the crumb hardness, cohesiveness, springiness, gumminess and chewiness, the results indicated that the best result was obtained when cakes were baked for 15 min at the par-baking stage. Overall, the cakes became firmer, less cohesive and less dry crumb as the intermediate storage time increased, whereas springiness increased.     

小麦储藏水分、温度和真菌生长危害进程预测的研究

对小麦储藏水分、温度、真菌最初生长时间和危害进程进行了初步探索性研究。采用喷雾着水方法将样品水分调至13.2%、13.6%、14.0%、14.5%、15.1%、15.5%、16.9%,分别于10、15、20、25、30、35℃恒温箱模拟储藏,定期检测各样品真菌生长变化情况,周期为120 d。结果表明,小麦在不同温度储藏,随着温度增加,真菌生长速度加快,30℃时达到最高,35℃时生长速度降低。在6个试验温度中,从安全和经济角度评价,最佳储藏温度为20℃;16.9%水分的小麦,由于出现一些青霉生长,即使低温储藏,这个水分仍存在着较大风险;根据上述研究结果,研究首次提出了小麦储藏水分、温度和真菌最初生长关系曲线,小麦在不同温度下储藏,真菌危害进程所需的时间。由于储粮真菌生长影响因素的复杂性,本试验数据仅供参考。     

Solubilization of wheat gluten with sodium hydroxide

The solubility of wheat gluten may be increased greatly by treatment with 0.25 M sodium hydroxide. At temperatures of 40°C and above, the solubility of the protein exceeds 100 mg/ml in a reaction time of 6 hr or less. The products from the reaction of 60°C and 80°C were darker than the original gluten and had an unpleasant odour of H₂S on dissolution in water. They also contained traces of lysinoalanine. The 40°C reaction product was about the same colour as gluten, and its solutions in water did not smell of H₂S. Reaction of gluten at 20°C also caused a large increase in solubility, but after 24 hr the solubility was only 77 mg/ml. This product was also of the same colour as gluten, and did not smell of H₂S in solution. Neither the 20°C nor the 40°C products contained detectable traces of lysinoalanine. For reasons of flavour, colour, lysinoalanine content and economy of time, the optimum reaction conditions are 6 hr at 40°C.     

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.     

The effects of grasshopper carcasses as dockage in stored wheat

In years of high grasshopper field populations, large numbers may be collected with harvested grain and deposited into storage. Little is known about the impact of grasshopper carcasses on stored-wheat quality; therefore, this study was conducted to determine such effects. Ninety-six glass bottles (237 mL capacity) were filled with 120 g of clean No. 1 wheat conditioned to 14.5% or 15.5% moisture content. Two-striped grasshoppers, Melanoplus bivittatus were collected in the summer of 2004 near Elie, MB, Canada and euthanized. Six grams of whole grasshoppers were mixed into half the bottles of each moisture content. All bottles were sealed and 12 bottles with and without grasshoppers were incubated at 25 °C and 50% relative humidity (r.h.), 25 °C and 75% r.h. 30 °C and 50% r.h. and 30 °C and 75% r.h. for 24 wk. Four bottles with and without insects were assessed every 4 wk for fat acidity value, seed microfloral infection and germination. The experiment was repeated and data pooled for statistical analysis (ANOVA). Significant differences (P < 0.05) arose between grasshopper and control treatments. Mean fat acidity values for wheat reached 32.99 mg KOH/100 g with grasshoppers compared to 25.23 mg KOH/100 g without carcasses. Initial seed germination of 98% rapidly declined to below 20% with grasshoppers between 4 wk and 8 wk; the majority of seeds were dead in the 75% r.h. treatments by 12 wk. Mean infection by the post-harvest fungi, Aspergillus glaucus group with grasshoppers ranged from 80.5 to 92% compared to 25–79.8% in controls. Penicillium spp. infection at 25 °C and 75% r.h. was 16.8% with grasshoppers and 4.2% without. Results from this experiment clearly demonstrate that the presence of grasshopper carcasses in stored wheat has negative consequences on grain quality. The implications of our research are discussed with respect to harvest practices and climate change.     

储藏小麦发热临界点及发热规律研究

研究不同含水量小麦在常温下储藏过程中温度的变化。结果表明:含水量16%的小麦在储藏过程中并未发热;含水量18%、20%、22%的小麦在常温储藏条件下发热临界点分别为27、12、4 d;粮堆中层位置最先发热且粮温高于上、下两层。     

Evaluation of postharvest preservation strategies for stored wheat seed in Ethiopia

Limited information exists on postharvest preservation strategies of stored wheat in Ethiopia. The present study was conducted to evaluate the effectiveness of on-the shelf postharvest storage strategies of stored wheat in the country. The experiment consisted of eight treatments; (1) metal silos, (2) Purdue Improved Crop Storage (PICS) bags, (3) Super GrainPro bags, (4) industrial filter cake dust applied to wheat in polypropylene bag, (5) plastic drums, 6) Triplex applied to wheat in polypropylene bag, 7) Triplex applied to wheat in plastic drum, and 8) polypropylene bag as control. Measurements of oxygen and carbon dioxide levels, live adults of insects per kg, percentage seed damage, and percentage of weight loss, germination and seedling vigor were determined every two months for six months. Results indicated that storage strategies such as PICS and Super GrainPro bags, filter cake, Triplex, and plastic drums led to a significantly lower live insect density compared to the control. Besides, Triplex and filter cake dust or use of hermetic bags also resulted in a significantly lower rate of seed weight loss (%) compared to the control. After six months of storage, means ± SD germination of seed from the polypropylene bag (control) had decreased to 68.0 ± 6.1% while wheat in all other storage strategies exhibited means ± SD germination capacity ranging from 92.0 ± 3.6% to 98.0 ± 1.0%. The present results demonstrate the potential of preserving stored wheat without relying on synthetic insecticides by using hermetic bags, filter cake, and Triplex, with advantages over traditional strategies used by smallholder farmers in Ethiopia. We recommend that hermetic bags, filter cake dust, and Triplex powder should be promoted for use by farmers for the postharvest preservation of their stored wheat.     

Mycotoxin production in amber durum wheat stored at 15 and 19% moisture content

Ochratoxin A and citrinin developed in 11 kg parcels of amber durum wheat at 15% and 19% initial moisture content (MC) exposed to simulated bulk storage in a Manitoba granary for 60 weeks between July 1984 and September 1985. Other biotic and abiotic variables were monitored throughout the storage period. Ochratoxin A reached maximum levels of 11.8 and 0.11 ppm at 19 and 15% initial MC, respectively, during weeks 44-48; citrinin reached levels of 80.0 and 0.65 ppm at these respective moistures during the same period. The effect of 19% initial MC was significantly greater for the following variables: ochratoxin A, citrinin, Aspergillus flavus, Aspergillus glaucus group species, Alternaria species, Aspergillus versicolor, bacteria, fungal propagule count, seed germination, O2, CO2, moisture content, and fat acidity. Principal component analysis indicated that the first two components, describing greater than 60% of the variability in the data, partially defined the ecological relationships leading to mycotoxin production in the stored durum wheat system.     

Effect of fungi and fungicides on the preservation of wheat seed stored with high and low moisture content

The protective effect of the fungicides captan, chloratalonil, pentachloronitrobenzene, thiram and the commercial mixture of captan and carboxin against storage fungi, as well as the possible toxic effect on seed viability, were studied on seed of the Salamanca wheat variety. The research was conducted with wheat seed stored at 25°C with a high and low moisture content: (a) seed stored at a high relative humidity of 85%, to allow the development of fungi and (b) seed stored under dry conditions, with seed moisture contents below 13%. The germination of wheat seed, either with high or low moisture content, was slightly inhibited by the fungicide carboxin immediately following seed treatment. It appears that the fungicide temporarily promoted a slight effect of seed dormancy; however, this effect disappeared during the storage period. The fungicides chloratalonil, captan and carboxin+captan prevented the activity of the storage fungi, and protected the germination of the wheat seed stored at 85% relative humidity.