Degradation of organophosphorus pesticides in wheat during cookie processing

For investigating carryover of some organophosphorus pesticide residues in the cereal food chain from grain to consumer, a study was set up on wheat bran, flour and cookies, with and without bran. Special emphasis was given to malathion and chlorpyrifos-methyl residues in cookies for better protection of consumers. Pesticide-free wheat was placed in a small-scale model of a commercial storage vessel and treated with these pesticides. The residue levels of insecticides were determined in wheat, as well as in bran, flour and cookies produced from stored wheat at various time intervals during storage. A multiresidue analysis was performed using GC–NPD and GC–MS. Malathion and chlorpyrifos-methyl residue levels were higher than the maximum residue limits (MRLs) in wheat after 240 days of storage. MRLs established by the EC for malathion and chlorpyrifos-methyl in wheat are 8 and 3 mg kg⁻¹, respectively. The residue levels of insecticides in flour samples also exceeded the MRL (2 mg kg⁻¹ for both insecticides). Eight months of storage were not effective for reducing the residues in wheat to the levels below MRLs. Although, considerable amounts of the insecticides remained in the bran and flour, the cookie processing significantly reduced the concentrations in general. Chlorpyrifos-methyl was more persistent than was malathion and comparatively less degradation occurred during milling and cookie processing due to its physicochemical properties.     

Faba bean (Vicia faba L.) seeds darken rapidly and phenolic content falls when stored at higher temperature, moisture and light intensity

Faba beans cv. Fiesta with seed moisture content (SMC) modified to 8, 10, 12 and 14% were packed in polyethylene lined aluminium foil bags and stored at 5, 15, 20, 25, 30, 37, 45, 50 or 60 °C (± 2 °C) for one year. Samples were analysed for moisture content and seed coat (testa) colour over the storage period using a chroma meter. A continuous increase in L^∗ and b^∗ values was found in all samples with the passage of time whereas a^∗ values first increased and then decreased in samples stored at relatively high temperatures (≥ 37 °C). The initial beige testa colour changed to light brown, dark reddish-brown or almost black depending on storage conditions. The higher the temperature and SMC the faster the rate of change in colour (?E_ab^∗ values). Seeds with 8% SMC had more stable testa colour compared to seeds with higher SMC. Exposure to artificial light (350 μ mol m⁻² s⁻¹) substantially accelerated the colour darkening. Cotyledons stored at 37 ± 2 °C also darkened with the storage time. A loss in total free phenolics, total tannins and proanthocyanidins was found with increased darkness of testa and cotyledons during storage.     

Synchrotron based infrared imaging study of compositional changes in stored wheat due to infection with Aspergillus glaucus

Fungi are one of the serious causes of spoilage in stored grain including wheat. Aspergillus spp. is one of the most common storage fungi that spoils stored wheat. The damage caused by fungi adversely affects the quality of wheat and reduces its nutritional composition. Present methods of analysing chemical composition of wheat and other cereals using wet chemistry are destructive and use bulk grain and thus rely on bulk analysis. Grains, similar to other biological materials, are highly non-homogenous, hence, bulk analysis which causes damage to intrinsic structure of kernels, cannot be used for characterization of single kernels and studying the compositional distribution within a single kernel. In the present work, synchrotron based high resolution infrared imaging was used to study the compositional changes in stored wheat due to fungal damage. Clear differences between healthy and damaged wheat endosperm spectra were observed at peaks around 1740, 1595, and 1250 cm⁻¹. The difference in the absorption of infrared radiation was likely caused due to reduced lipid (1740 cm⁻¹), lignin (1595 cm⁻¹) and cellulose (1250 cm⁻¹) content in damaged wheat endosperm.     

Field trials on the efficacy of Beauveria bassiana,diatomaceous earth and Imidacloprid for the protection of wheat grains from four major stored grain insect pests

We assessed the insecticidal efficacy of Beauveria bassiana, diatomaceous earth (DE) and the neonicotinoid Imidacloprid against four major insect species of stored grain pests during field trials conducted on small farms located in four districts of Punjab, Pakistan. In each district, a 40 kg lot of wheat grain was admixed with B. bassiana (3 × 10¹⁰ conidia kg⁻¹), DE (150 ppm) and Imidacloprid (5.0 ppm) alone and in different combinations. Each lot was divided subsequently into four equal parts (10 kg each), packed in polypropylene bags, artificially infested, labeled and stored at the farms under natural environmental conditions up to 6 months. Sampling was carried out every 30 d to record the total number of dead and alive adults, as well as the percent of grain damage in treated and untreated (control) grains. Results revealed a significant difference among the treatments, test insect species and the storage period. For each district, the combined treatments provided better control of all tested insect species compared with each treatment alone. The least number of surviving adults and minimum percent grain damage was observed for Imidacloprid and DE combination, but was outperformed by the DE treatment with B. bassiana for long-term protection. For all grain protectants, we obtained the same order of susceptibility level among the test species (i.e. Liposcelis paeta > Cryptolestes ferrugineus > Rhyzopertha dominica > Tribolium castaneum). The results of the present study suggested that DE, insect pathogenic fungi and Imidacloprid can be effectively used for the protection of wheat stored at small-scale farmer's fields.     

Phosphine fumigation of silo bags

Fumigation with phosphine has the potential to disinfest grain stored in silo bags but only limited research has been conducted on whether phosphine fumigation can be undertaken effectively and safely in this form of storage. Fumigation with phosphine was tested on two (70 m) replicate silo bags each containing 240 t of wheat (9.9 and 9.2% m.c.). The target application rate of phosphine was 1.5 g m⁻³ with a fumigation period of 17 days. Aluminium phosphide tablets were inserted into each bag at ten release points spaced at 7 m intervals starting 3.5 m from either end of the bag. A total of 14 bioassay cages containing mixed age populations of strongly phosphine resistant Rhyzopertha dominica (F.) were inserted into each fumigated silo bag. Complete control of all life stages of R. dominica was achieved at all locations in the fumigated silo bags. Phosphine concentrations at release points increased rapidly and remained high for the duration of the fumigation. Concentrations at midway points were always lower than at the release points but exceeded 215 ppm for ten days. The diffusion coefficient of available phosphine averaged over the first three full days of the fumigation for both fumigated silo bags was 2.8 × 10⁻⁷. Venting the silo bag with an aeration fan reduced the phosphine concentration by 99% after 12 h. Relatively small amounts of phosphine continued to desorb after the venting period. Although grain temperature at the core of the silo bags remained stable at 29 °C for 17 days, grain at the surface of the silo bags fluctuated daily with a mean of 29 °C. The results demonstrate that silo bags can be fumigated with phosphine for complete control of infestations of strongly phosphine resistant R. dominica and potentially other species.     

Comparing physicochemical properties of banana pulp and peel flours prepared from green and ripe fruits

Banana pulp and peel flour prepared from green and ripe Cavendish banana were assessed for physicochemical properties such as pH, total soluble solids (TSS), water holding capacity (WHC) and oil holding capacity (OHC) at 40, 60 and 80 °C, colour values L^∗, a^∗ and b^∗, back extrusion force (BEF) and viscosity. Data obtained were analysed by MANOVA, discriminant analysis and cluster analysis. All statistical analyses showed that physicochemical properties of flour prepared from pulp and peel, and green and ripe banana were different from each other. TSS, WHC40, WHC60 and BEF can be used to discriminate between peel and pulp flour, whilst TSS and viscosity can be used to discriminate between flour prepared from green and ripe banana.     

Quality parameters of wheat grain and flour as influenced by treatments with natural zeolite and diatomaceous earth formulations,grain infestation status and endosperm vitreousness

This study investigated the changes in quality parameters of wheat (mealy and vitreous) non-infested and infested with Sitophilus oryzae (L.) caused by treatments with inert dusts: natural zeolite, two diatomaceous earths from Serbia, and a commercial product enhanced DE Protect-It^®.Inert dust treatments, regardless of infestation status, significantly reduced wheat test weight. This was more marked in mealy (8.3%) rather than in vitreous wheat grain (2.7%). Content of silicon dioxide (SiO₂) in flour from infested lots was significantly higher than in non-infested ones. Treatments with all formulations of inert dusts significantly affected flour water absorption in the non-infested wheat lots. Non-infested high vitreous wheat treated with Protect-It^® showed the highest moisture absorption (61.9 g.100 g⁻¹) in comparison with the control (59.7 g.100 g⁻¹). Significant improvement in dough rheology was observed in the infested soft and hard wheat, particularly through rise of dough energy. Small-deformation tests implied certain dough weakening effects of inert dusts in vitreous wheat but this was not observed in standard large-deformation rheological tests.Application of inert dusts shows an ability to improve some aspects of the technological quality of wheat.     

Some properties of corn grains and their flours I: Physicochemical,functional and chapati-making properties of flours

The variability in physical (1000 kernel weight and bulk density) and mechanical (rupture force) properties of grains from different Indian corn varieties (African tall, Ageti, Early composite, Girja, Navjot, Parbhat, Partap, Pb sathi and Vijay) were studied. The functional (colour, gelatinization, retrogradation and pasting) and chapati-making properties of flours milled from corn varieties were evaluated. African tall flour showed the highest enthalpy of gelatinization (ΔH_gel), peak-, trough-, breakdown-, final-, and setback viscosities, and L^∗ (84.4) value and resulted in chapaties with higher extensibility (5.76 mm) and of light colour. African tall flour, with the lowest protein content, showed the lowest grain rupture force. Amylose content and hardness of starch gel from African tall were found to be the lowest among all corn varieties. Girja flour, with the lowest transition temperatures and ΔH_gel, showed the lowest extensibility of chapaties made from it. Pearson correlations between physical and textural properties of corn grains and the functional properties of their flours were established. Rupture force of corn grain and protein content of flour showed a negative correlation with peak viscosity of flour (r = −0.917, and −0.863, p < 0.01). The protein content of flours was negatively correlated with L^∗ (r = −0.759, p < 0.01) value and positively with b^∗ (r = 0.635, p < 0.01) value. Pasting temperature of flours showed a significant negative correlation with peak, trough, breakdown, final and setback viscosities (r = −0.836, −0.846, −0.778, −0.871, and −0.847, respectively, p < 0.01). Pearson correlation was also established between the grain and starch properties. Rupture force of corn grains was positively correlated with the amylose content of starch (r = 0.950, p < 0.01).     

Effect of blending durum wheat flour with hard white wheat flour on the quality of yellow alkaline noodles

Yellow alkaline noodles (YAN) were prepared from durum and hard white wheat flour blends and evaluated for noodle color, appearance and cooked noodle texture. Raw noodle brightness, L^∗, and yellowness, b^∗, improved significantly with durum flour addition while significant increases in a^∗ values were observed at both 2 h and 24 h. The very low noodle speck count of white wheat noodles remained constant over the 24 h period at any durum flour addition. Noodle bite, MCS, decreased with the addition of durum flour, resistance to compression (RTC) remained equivalent to the hard white flour control while an associated improvement in cooked noodle recovery (REC) was observed. The study indicates that addition of durum flour at even the 25% level, offers a viable product with improved colour characteristics, consistent RTC and improved REC textural attributes. Uniaxial stress relaxation parameters of cooked noodles significantly correlated with the empirical texture measurements.     

Insecticidal effect of spinosad dust, in combination with diatomaceous earth, against two stored-grain beetle species

Laboratory bioassays were carried out to determine the efficacy of spinosad applied alone or combined with the diatomaceous earth (DE) SilicoSec against adult rice weevils, Sitophilus oryzae and confused flour beetles, Tribolium confusum. Efficacy was assessed on wheat and maize at three dosages of spinosad dust formulation (corresponding to 0.0625, 0.1875 and 0.625 ppm of active ingredient [AI] for S. oryzae and to 0.1875, 0.625 and 1.25 ppm of AI for T. confusum), alone or combined with SilicoSec at 150 ppm for S. oryzae and 250 ppm for T. confusum. The mortality of S. oryzae exposed for 14 d on wheat treated with spinosad ranged between 83% and 100%. Conversely, the mortality of S. oryzae on maize treated with DE or on maize treated with lower doses of spinosad dust did not exceed 19% and was only 59% on maize with the highest spinosad dust treatment. Generally, the presence of SilicoSec combined with spinosad did not significantly increase S. oryzae mortality compared with spinosad alone. For T. confusum, mortality on both commodities was lower than for S. oryzae. After 14 d of exposure on wheat, mortality was 14% at the highest dose of spinosad, but increased to 33% in the presence of DE. Similar results were also obtained for T. confusum exposed on treated maize, which indicated a joint action between spinosad and DE. In the case of S. oryzae, the inclusion of DE reduced progeny production in comparison with spinosad alone. Progeny production of T. confusum was relatively low in all treatments, compared to progeny production of S. oryzae. The results of the study show the potential of combination treatments of spinosad dust and DE, but efficacy varies with the target insect species and commodity.     

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.     

Natural levels of ethyl formate in stored grains determined using an improved method of analysis

Ethyl formate was readily determined with a gas chromatograph (GC) equipped with a flame ionisation detector. Natural levels of ethyl formate in Australian wheat, barley, oats, and canola were analysed by GC, after extraction with ammonium nitrate solution. Background levels of ethyl formate were present in newly harvested and stored grain. The levels of ethyl formate (0.1-0.6 mg kg⁻¹) in grains varied with commodity, temperature, moisture and period of storage. The values ranged from 0.1 to 0.2 mg kg⁻¹ for newly harvested wheat, barley and oats, and 0.3-0.4 mg kg⁻¹ for newly harvested canola. Ethyl formate was present in grains at harvest, increased during the first 7 months of storage, and then began to decline, particularly at grain temperatures higher than 25°C and moisture contents higher than 12.5% (for wheat, barley and oats) and 6.5% (for canola). The natural levels of ethyl formate should be considered when establishing maximum residue limits.     

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。     

Effect of frozen storage conditions (temperature and length of storage) on microbiological and sensory quality of rustic crossbred beef at different states of ageing

The effect of frozen storage conditions on meat from 36 Morucha × Charolais crossbred yearlings was studied. Slices of M. Longissimus thoracis were randomly assigned to groups arising from the combination of experimental factors. These factors were: ageing extent (3 and 10 days), length of frozen storage (0, 30, 75 and 90 days) and temperature (−20 and −80 °C). Regarding microbiological counts, although values were acceptable in all cases, longer storage time and longer previous ageing extent provided higher phychrotrophic bacteria counts. As frozen storage period increased, colorimetric parameters L^∗, a^∗ and C^∗ decreased, but H^∗ increased. Regarding Warner–Braztler shear force and tenderness values, an interaction (p < 0.05) between frozen storage and post-mortem ageing resulted from larger differences between frozen storage periods at shorter ageing periods than those at longer ageing periods. Frozen storage for 90 days resulted in a reduction in water holding capacity, without differences in juiciness. No effect of freezing temperature was observed in any of the parameters studied.     

Physicochemical and microbiological changes of “Souvlaki” – A Greek delicacy lamb meat product: Evaluation of shelf-life using microbial,colour and lipid oxidation parameters

Fresh Souvlaki-type lamb meat was packaged under vacuum (VP) and modified atmospheres (MAs) and stored under refrigeration (4 °C) for a period of 13 days. The following gas mixtures were used: M1: 30%/70% (CO₂/N₂) and M2: 70%/30% (CO₂/N₂). Identical samples were aerobically-packaged and used as control samples. Quality evaluation of product stored under the above packaging conditions was conducted using physicochemical and microbiological analyses. Of the chemical parameters determined, pH values of product showed no significant differences for all packaging treatments as a function of storage time. Lipid oxidation of lamb meat was enhanced by aerobic storage and gas mixture M1, whereas VP and gas mixture M2 controlled lipid oxidation to a greater extent. Souvlaki colour stability (as determined by a^∗, b^∗ and L^∗ values) was not negatively affected by either VP or MA conditions during the 13 days of storage. Of the two MAs and VP used, gas mixture M2 and VP were the most effective treatments for the inhibition of total viable counts (TVC), Pseudomonas spp., yeasts and Brochothrix thermosphacta in Souvlaki meat. Lactic acid bacteria (LAB) and Enterobacteriaceae were also found in the microbial flora of Souvlaki and increased during storage under all packaging conditions used. Based on microbiological analysis data and on the proposed a^∗ values, the use of VP and MAP (M2: 70%CO₂/30N₂) extended the shelf-life of “Souvlaki” meat stored at 4 °C by approximately 4–5 days compared to aerobic packaging.     

Evaluation of lactic acid and monolaurin to controlListeria monocytogeneson Stracchino cheese

The behaviour ofListeria monocytogeneswas evaluated during storage of Italian Stracchino cheese dipped in lactic acid (1.4%) or surface treated with (1)-monolauroyl-(rac)-glycerol (monolaurin, 200 μg cm⁻²). The cheese was surface inoculated with approximately 5×10²cfu cm⁻²ofL. monocytogenes, and stored under vacuum at 5°C for 12 days. The lactic acid treatment resulted in lower counts (P<0.05) ofL. monocytogenescompared with counts on untreated cheese washed with water. When lactic-treated cheese was stored at 5°C, levels ofL. monocytogenesdid not change appreciably. Treating cheese with monolaurin also significantly reduced the number ofL. monocytogenes. Furthermore, 12 day counts were less than the untreated control.     

Potentially toxigenic fungi from selected grains and grain products

A total of 85 grain and grain product samples (including corn meal, corn muffin mix, popcorn, various types of rice, and self‐rising, all‐purpose unbleached and whole wheat flour) from U.S. retail were tested for fungal contamination levels and profiles using conventional plating as well as molecular methods. The results of this study showed that over 90% of wheat flour and corn product samples and 73% of rice samples tested carried live fungi. Popcorn carried the highest fungal levels reaching 5.45 log₁₀ colony forming units (cfu) per gram followed by corn meal (reaching 5.38 log₁₀ cfu/g). Mold and yeast counts in rice and wheat flour reached 3.30 log₁₀ and 3.28 log₁₀ cfu/g, respectively. The predominant molds in wheat flour were aspergilli and fusaria found in 50 and 46% of samples, respectively; Fusarium spp. were the most frequent contaminants of corn‐based products found in 74% of the samples followed by penicillia (present in 44% of tested samples). Rice, conversely, contained mainly Aspergillus, Fusarium, and yeasts (each found in 21% of the samples).

Practical applications

Toxigenic molds are often contaminating stored grains and grain products and under improper storage conditions could cause spoilage of these commodities accompanied with production of toxic secondary metabolites, mycotoxins. Mycotoxins are known to cause illnesses in humans and animals. Therefore, monitoring the presence and inhibiting the growth of these organisms is critical for achieving and maintaining high quality products, suitable for human and animal consumption, and free of health hazards. Establishing toxigenic mold profiles in stored grains and their derivatives can point to correct storage management and thus reduction/elimination of spoilage and mycotoxin production in these products. In this study we tested several corn, rice, and wheat flour commodities for live potentially toxigenic fungal species. Our findings can help select proper storage management techniques for these commodities.     

Uneven application can influence the efficacy of s-methoprene against Rhyzopertha dominica (F.) in wheat

The Juvenile Hormone analogue s-methoprene is used to protect stored grain from pests such as the lesser grain borer, Rhyzopertha dominica (F.). The possibility that uneven application influences s-methoprene efficacy against this species was investigated in the laboratory. Adults of methoprene-susceptible strains were exposed for 14 days to wheat treated at doses of up to 0.6 mg kg⁻¹, or to mixtures of treated and untreated wheat giving equivalent average doses. Adult mortality after exposure to treated wheat was negligible in all cases (≤3.3%) and there was no significant effect of either average dose or evenness of application. In contrast, the number of adult progeny depended on both the average dose and evenness of application. Average doses of 0.3 and 0.6 mg kg⁻¹ reduced the number of live F₁ adults by 99–100% relative to the untreated wheat and no effect of evenness of application was detected. At lower doses, however, efficacy tended to decrease with increasing unevenness of application. When adults from the parental generation were transferred to untreated wheat for another 14 days neither the average dose nor evenness of application in the wheat from which they came had any significant effect on reproduction of these adults. This study demonstrates that uneven application can reduce the efficacy of s-methoprene against R. dominica, but that this is unlikely to influence the performance of s-methoprene against susceptible populations at target doses likely to be used in practice (e.g. 0.6 mg kg⁻¹ in Australia). However, the possibility that uneven application leads to underdosing and selects for resistance should be investigated.     

Film preparation with high protein defatted peanut flour: characterisation and potential use as food packaging

The purpose of this study was to prepare a defatted peanut flour‐based film (DPFF); to characterise their physicochemical, optical, barrier and mechanical properties; and to evaluate the defatted peanut flour package efficacy to preserve the chemical quality of sunflower oil during storage. The film presented high lightness values (L* = 86.83). The water vapour permeability was 5.44 × 10^?11 g m^?1 s^?1 Pa^?1. Tensile strength and percentage of elongation were 1.01 MPa and 84.01%, respectively. Sunflower oil samples packaged in defatted peanut flour packages (DPFP) were stored during 67 days at room temperature. Peroxide value and conjugated dienes increased less for sunflower oil conditioned in DPFP and high barrier plastic pouches (EVOH) during storage than sunflower oil conditioned in Petri dishes (C). The use of DPFP improved the chemical stability of sunflower oil during storage. The DPFF showed suitable film properties, and also, the capacity to be incorporated in food packaging applications.