Residue levels of malathion and fenitrothion and their metabolites in postharvest treated barley during storage and malting

In order to investigate residue levels of malathion and fenitrothion and their metabolites (malaoxon, isomalathion and fenitrooxon) during storage and malting, pesticide-free barley was treated with these insecticides. Barley was placed in a sealed plastic container and treated with a dust of malathion (2%). Fenitrothion emulsion (41.6% wettable powder) was applied onto the walls of a small-scale storage vessel. Residues were determined in barley at about 1-month intervals during storage and in malt produced from the barley stored at various times. The analysis of the residues was carried out by GC equipped with a nitrogen-phosphorus detector (NPD). Although the approved doses of insecticides for stored grain were used, the residue levels exceeded the maximum residue limits (MRLs) at the beginning of storage. While the degradation of malathion and isomalathion in barley was observed to be about 65–72% during the storage period, the malaoxon was degraded extensively (85%). A significant percentage of fenitrothion residues (80%) were dissipated from grains for the short-term storage probably because of hot weather conditions. In malt, rates of degradation and volatilisation of the residues increased by the heat involved in malting. The carryover of the residues from barley into malt was also found to be dependent on the log P_ow (partition coefficient between n-octanol and water) values of the insecticides.     

Electrophoretic and HPLC methods for comparative study of the protein fractions of malts,worts and beers produced from Scarlett and Prestige barley (Hordeum vulgare L.) varieties

Sodium dodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and reversed-phase high performance liquid chromatography (RP-HPLC) methods were used for studying the protein fractions (hordeins; albumins and other soluble proteins) of Scarlett and Prestige barley malts and to follow changes of the protein profile of worts and beers from these two malt varieties. Similar industrial brewing conditions were applied for both varieties.     

Water diffusion and enzyme activities during malting of barley grains: A relationship assessment

Maximal water uptake and diffusivity were determined from experimental soaking curves using analytical solution of the second Fick’s law in four barley samples displaying distinct hydrolytic activities during malting. Water diffusivities in the whole grains, were found to vary between 5.28 and 7.61 × 10⁻¹² m²/s, whereas those of the endosperms were 5-7-fold higher, ranging between 35.2 and 49.5 × 10⁻¹² m²/s. These differences highlighted the potential barrier role of the grain outer layers. The relationships between maximal water uptake, water diffusivity and grain biochemical and structural parameters (i.e. hardness and other less studied parameters such as vitreousness and porosity) was investigated. The lowest water diffusivity value was obtained for the barley sample displaying the lowest porosity, highest hardness and vitreousness but the highest enzymatic activity during malting, in contradiction with what is generally stated. Water diffusion was not found as the limiting factor for malt quality and, thus, its role during barley steeping has to be reconsidered.     

Effects of boiling, warm-holding, mashing and cooling on the levels of enzyme-resistant potato starch

Summary The effects of boiling, warm-holding, cooling and mashing on the enzyme-resistant starch (ERS) content of potatoes was studied together with inter-tuber and inter-cultivar variation in ERS content. Inter-tuber variation in ERS content was small and mean values (on a dry matter basis) for boiled and raw potatoes were 10.7 and 74.2% (cultivar Rooster) and 10.8 and 74.3% (cultivar Anna). There was no significant difference between the ERS values of boiled potatoes of seven cultivars (range 10.0–10.8%). Warm-holding mashed potatoes at 65–70 °C for 1 hr raised ERS values from 2.20 to 4.80%. In a separate test slow cooling over 2 hr to 21 °C raised the ERS content from 3.65 to 6.35%. Multiple cook-cool (3×) gave ERS contents of 23.2 and 18.2% for boiled potatoes held for 24 hr at 4 or 20 °C. Mashing and freezing raised ERS values by 1–2%.     

Changes in β-glucan and other carbohydrate components of barley during malting

Changes in total (1→3), (1→4)-β-glucan content were followed during the micro-malting of nine varieties of barley with a wide range of malting qualities. These changes were related to estimates of endosperm modification based upon staining with Calcofluor. β-Glucan content declined from an average of 3.54% in the barley to 0.75% in the malt. Pentosan and total starch (including starch-derived oligosaccharides) levels showed comparatively little change during malting. β-Glucan composition of the barley was a poor indicator of malting performance. However, the β-glucan, starch and xylose contents of the malt all showed significant correlations with malt extract. Estimation of malt β-glucan content gave the best indication of malt quality. Direct determination of β-glucan may be of more value in assessing malt quality than indirect techniques based upon assessing modification of stained grains.     

Insecticidal activity of three diatomaceous earths on lesser grain borer,Rhyzopertha dominica F., and their effects on wheat,barley, rye,oats and triticale grain properties

This study aimed to evaluate insecticidal activity of three diatomaceous earths DEs, two originated from Serbia (DE S-1 and DE S-2) and one commercial formulation (Protect-It, Hedley Technologies Ltd. Canada) applied at rates of 0.5, 1.0 and 1.5 g/kg (500, 1000 and 1500 ppm) on Rhyzopertha dominica in wheat, barley, rye, oats and triticale grains and their effects on mass of kernels and several properties: adherence, hectolitre mass, moisture, protein and ash contents. Mortality of R. dominica adults increased with exposure duration and DEs rates. In all tested grains after the longest exposure period (21 days), 1.0 and 1.5 g/kg rates of Protect-It, and 1.5 g/kg rate of DE S-1 and DE S-2 (in barley) caused 95–100% mortality. Offspring reduction of ≥95% was recorded after the application of 1.0 and 1.5 g/kg of Protect-It and 1.5 g/kg of DE S-1. The lowest weight of damaged grain was found after applying 1.0 and 1.5 g/kg of DEs to all grain types, and the highest in rye and wheat treated with 0.5 g/kg DE S-1 and DE S-2, respectively. The highest DEs adherence of 83–95% was detected in wheat, and 87–92% in oats, and the lowest of 71–77% in rye and 59–73% in triticale. All DEs significantly reduced hectolitre mass of all grains, especially Protect-It, 3.6–8.8%. No negative effects of DEs were detected on moisture contents, and the contents of proteins and ashes in the grains. The changes were due to the activity of R. dominica.     

Fate of enniatins and beauvericin during the malting and brewing process determined by stable isotope dilution assays

The fate of enniatins A, A1, B, B1 and beauvericin during the malting and brewing process was investigated. Three batches of barley grains were used as starting material, one was naturally contaminated, two were artificially inoculated with Fusarium fungi. Samples were taken from each key step of the malting and brewing procedure, the levels of the toxins were determined with stable isotope dilution assays using liquid chromatography–tandem mass spectrometry detection. Significant increases of the toxins were found during germination of two batches of barley grains, resulting in green malts contamination up to a factor of 3.5 compared to grains before germination. Quantitative PCR analyses of fungal DNA revealed in all batches growth of Fusarium avenaceum during germination. After kilning, only 41–72% of the total amounts of the toxins in green malts remained in kilned malts. In subsequent mashing stage, the toxins in kilned malts predominantly were removed with spent grains. In the final beer, only one batch still contained 74 and 14 μg/kg of enniatin B and B1, respectively. Therefore, the carryover of these enniatins from the initial barley to final beer was less than 0.2% with the main amounts remaining in the spent grains and the malt rootlets.     

Effect of malting time,mashing temperature and added commercial enzymes on extract recovery from a Nigerian malted yellow sorghum variety

Preliminary microbiological studies carried out on sorghum grains showed that the major microorganisms found were mainly bacteria and that aflatoxin‐producing fungi were not found. The effect of added commercial enzyme preparations and different infusion mashing temperatures on extract yield, from sorghum malted at 30 °C, was studied. The infusion mashing method (65 °C) developed for mashing well‐modified barley malt produces poor extract yields with sorghum malt. The extract yield from the sorghum malt in this study was very low with infusion mashing at 65 °C, without the addition of commercial enzyme preparations. A higher extract yield was obtained from the sorghum malt, without the commercial enzyme addition, when using infusion mashing at 85 °C. Both infusion mashing temperatures (65 and 85 °C) showed an improved extract yield over the control malt when commercial enzyme preparations were used during mashing of the sorghum malt. The added enzyme preparations resulted in a higher extract yield from the germinated sorghum when infusion mashing was performed at 65 °C over mashing at 85 °C. The use of individual commercial enzymes (α‐amylase, β‐glucanase, protease, xylanase, saccharifying enzyme and combinations of some hydrolytic enzyme) increased extract yields, when complemented with the enzymes that had developed in the sorghum malt. Copyright © 2016 The Institute of Brewing & Distilling     

Monitoring of monosaccharides,oligosaccharides, ethanol and glycerol during wort fermentation by biosensors,HPLC and spectrophotometry

The aim of the present study was to analyze sugar levels (namely maltose, maltotriose, glucose and fructose) and alcohols (ethanol and glycerol) during the fermentation process in wort samples by amperometric enzymatic biosensors developed by our research group for industrial application, HPLC and spectrophotometry, and to compare the suitability of the presented methods for determination of individual analytes. We can conclude that for the specific monitoring of maltose or maltotriose only the HPLC method was suitable. On the other hand, biosensors and spectrophotometry reflected a decrease in total sugar concentration better and were able to detect both glucose and fructose in the later stages of fermentation, while HPLC was not. This can be attributed to the low detection limits and good sensitivity of the proposed methods. For the ethanol and glycerol analysis all methods proved to be suitable. However, concerning the cost expenses and time analysis, biosensors represented the best option.     

Influence of seed mycoflora and harvesting conditions on milling,popping and malting qualities of sorghum (Sorghum bicolor)

Four cultivars of sorghum were artificially inoculated with Fusarium moniliforme conidia at flowering and bagged. These samples along with their untreated controls were harvested at physiological maturity and 2 weeks after physiological maturity. The grains obtained from both the treatments were studied for their milling, malting and popping characteristics. Grains harvested at physiological maturity stage possessed superior milling and malting characteristics whereas late-harvested grains exhibited better popping characteristics. Milling and popping reduced the seed mycoflora considerably.     

Analysis of total polyphenols,bitterness and haze in pale and dark lager beers produced under different mashing and boiling conditions

Malting and brewing processes should be performed under process conditions in a way that minimizes beer bitterness, maximizes polyphenol content and reduces the amount of raw materials ending up in solution in the form of hazes, particles and precipitates. This work examined the influence of different mashing temperature conditions and boiling procedures on the total polyphenol content, bitterness and haze of pale and dark lager beers produced on an industrial scale. Two hop types (hop pellets and/or hop extract) and different hop varieties (Hallertau Magnum, Styrian Goldings, Saaz, Aurora and Sladek) were utilized with varying times of hop addition into the wort. Measurements of total polyphenols, colour, bitterness, alcohol content, CO₂ and pH were carried out on the beer samples. Results showed that pale lager beers had a lower total polyphenol concentration (110–179 mg/L) than dark beers (230–260 mg/L). Using hop extracts instead of hop pellets led to a lower total polyphenol concentration and to less beer foam creation. The change in the proteolytic temperature during mashing only had an influence on the total polyphenol content in the pale lager beer hopped with the pellets. Conducting proteolysis over a 20 min period led to a haze increase in all of the beers produced. In the dark beer, the haze was substantial after just 10 min at 52°C. Copyright © 2015 The Institute of Brewing & Distilling     

Fate of imidacloprid and acetamiprid residues during black tea manufacture and transfer into tea infusion

The objective of this paper is to investigate the loss/stability of neonicotinoids (imidacloprid and acetamiprid) residues during the manufacture of black tea and to study the transfer of these pesticides from made tea to its infusion. For orthodox black tea, the manufacturing process involves leaf harvesting (plucking two leaves and a bud), withering, rolling, fermentation (oxidation), and drying. Initial withering and final drying resulted in the loss of pesticide residues, but no significant reduction in residue levels resulted from the rolling and fermentation steps. The drying process resulted in a residue transfer of 64–70% and 69–74% of the initial level, whereas the brewing process resulted in a residue transfer of 37–39% and 45–49% of imidacloprid and acetamiprid, respectively, from dried tea into the infusion. The decrease in acetamiprid levels during drying was also significant (8–13%), whereas the total loss during the manufacturing process ranged from 26 to 31%. Further, brewing for longer periods (an extended brewing time) resulted in higher transfer (up to 44% for imidacloprid and 53% for acetamiprid) of pesticides to tea infusion. Further, the extent of pesticide leaching depends on its water solubility, partition coefficient, and the brewing time.     

基于COMSOL的平房仓冷却通风过程中粮堆热湿耦合传递研究

粮仓冷却干燥通风是确保储粮安全的重要技术措施,在此过程中粮堆内部的热湿耦合迁移过程非常复杂。在COMSOL软件中,建立了冷却干燥通风过程中高大平房仓的三维物理模型,通过修改COMSOL内置材料方程、耦合渗流、能量守恒、动量守恒和水分迁移控制方程,以实测的送风空气温度和湿度为入口边界条件,数值模拟了湍流、湿空气传热、湿空气传质、多孔介质传热、多孔介质传质等多个物理场,并考虑了热湿耦合、温度耦合和流动耦合,对高大平房仓粮堆内冷却干燥通风过程中的热湿迁移规律进行了研究。基于实际高大平房仓的验证结果表明,通过修改COMSOL内置方程可以准确模拟预测冷却干燥通风过程中粮堆内热湿耦合传递过程,数值模拟结果可用于指导粮仓冷却干燥通风过程和粮仓通风系统优化。     

Mathematical modelling and numerical simulation of phosphine flow during grain fumigation in leaky cylindrical silos

The phosphine distribution in a cylindrical silo containing grain is predicted. A three-dimensional mathematical model, which accounts for multicomponent gas phase transport and the sorption of phosphine into the grain kernel is developed. In addition, a simple model is presented to describe the death of insects within the grain as a function of their exposure to phosphine gas. The proposed model is solved using the commercially available computational fluid dynamics (CFD) software, FLUENT, together with our own C code to customize the solver in order to incorporate the models for sorption and insect extinction. Two types of fumigation delivery are studied, namely, fan-forced from the base of the silo and tablet from the top of the silo. An analysis of the predicted phosphine distribution shows that during fan forced fumigation, the position of the leaky area is very important to the development of the gas flow field and the phosphine distribution in the silo. If the leak is in the lower section of the silo, insects that exist near the top of the silo may not be eradicated. However, the position of a leak does not affect phosphine distribution during tablet fumigation. For such fumigation in a typical silo configuration, phosphine concentrations remain low near the base of the silo. Furthermore, we find that half-life pressure test readings are not an indicator of phosphine distribution during tablet fumigation.     

Fate of the fusarium mycotoxins,deoxynivalenol, nivalenol and zearalenone,during extrusion of wholemeal wheat grain

In the European Union, deoxynivalenol in cereals and cereal products is controlled by recent legislation with the objective of minimizing consumer exposure to this mycotoxin. Relatively few studies have examined the loss of Fusarium mycotoxins during processing and whether this is accurately reflected by the processing factors. The behaviour of deoxynivalenol, nivalenol and zearalenone during extrusion of naturally contaminated wholemeal wheat flour has been examined using pilot-scale equipment. Factors examined were temperature and moisture content. Concentrations of the three mycotoxins were little changed by extrusion although the amount of deoxynivalenol decreased at the lowest moisture content. However, this effect did not appear to be temperature-dependent, suggesting that the apparent loss is either due to binding or inability to extract the residue. Under some conditions, concentrations of the mycotoxins, particularly nivalenol, were higher after extrusion.     

Fate of the fusarium mycotoxins, deoxynivalenol, nivalenol and zearalenone, during extrusion of wholemeal wheat grain

In the European Union, deoxynivalenol in cereals and cereal products is controlled by recent legislation with the objective of minimizing consumer exposure to this mycotoxin. Relatively few studies have examined the loss of Fusarium mycotoxins during processing and whether this is accurately reflected by the processing factors. The behaviour of deoxynivalenol, nivalenol and zearalenone during extrusion of naturally contaminated wholemeal wheat flour has been examined using pilot-scale equipment. Factors examined were temperature and moisture content. Concentrations of the three mycotoxins were little changed by extrusion although the amount of deoxynivalenol decreased at the lowest moisture content. However, this effect did not appear to be temperature-dependent, suggesting that the apparent loss is either due to binding or inability to extract the residue. Under some conditions, concentrations of the mycotoxins, particularly nivalenol, were higher after extrusion.     

Study on the water state,mobility and textural property of Chinese noodles during boiling

The water mobility, state and textural properties of Chinese fresh noodles (CFNs) and Chinese dried noodles (CDNs) made from same wheat cultivar were measured during boiling using low-field nuclear magnetic resonance (LF-NMR), low-field nuclear magnetic Imaging (LF-NMI) and a textural analyser. ‘The oil immersion method’ was applied to gain the clear images from LF-NMI measurement. The distributions of the three water states (T₂₁, T₂₂ and T₂₃) in the noodles were distinguished. The results indicated that water mobility in noodles was closely related to the gelatinisation of noodle starch. Compared with CFNs, CDNs need a longer cooking time for water mobility and starch gelatinisation. The results of the cooked noodle profiles showed that the cooked CDNs (8 min) had an undesirable textural properties compared with the cooked CFNs (2 min). The longer cooking time of CDNs is responsible for its undesirable texture since the textural properties change during the longer cooking time.