Salicylaldehyde is a characteristic aroma component of buckwheat groats

Salicylaldehyde (2-hydroxybenzaldehyde) was identified as a characteristic component of buckwheat groats aroma by a sensory analysis guided fractionation of the extract. The extract with the strongest odour was prepared by petroleum ether extraction of water soaked groats. This extract was further extracted with sodium hydrogen carbonate solution and purified by a preparative layer chromatography and identified by NMR, MS and IR spectroscopy. A capillary electrophoresis method was developed and used to determine salicylaldehyde content in buckwheat groats and flour samples. Traditionally dehulled buckwheat grain, which had the strongest odour, contained the highest concentration (1.6 ppm) of salicylaldehyde with an odour activity value (OAV) of 216.     

Change in the sugar content in oaten products, buckwheat and rice groats during their heat processing by cooking]

The sugar content in the grits and in a gruel cooked with samples of oats and buckwheat subjected to hydrothermal treatment under different conditions and also in the oat flour, a product of baby and dietetic nutrition, was quantified. Hydrothermal processing results in significant changes occurring individual sugars of the grit. During culinary treatment these changes are levelled out, but in the end the level of virtually all types of sugar is higher in the gruel cooked with hydrothermally treated grit than in that prepared with initial, untreated grit. The oats flour is distinguished by a high glucose, maltose, fructose and saccharose content. A fall of the reducing sugars level coming as a result of thermal and culinary treatment is explained by their participating in the reaction of melanoidine formation. On the other hand, a rise in their content under rigorous conditions and in the production of oat flour is due to the starting of the starch hydrolysis.     

Buckwheat groats production. Part. II The changes in the ultrastructure of buckwheat (Fagopyrum esculentum Moench) during processing

By means of a scanning electron microscope the changes in the ultrastructure of buckwheat in two different methods of groats production were investigated. Scanning electron micrographs taken from buckwheat assigned to fire and steam roasting did not show significant differences in the ultrastructure of both raw materials. It was found that steam roasting was responsible for more pronounced changes of buckwheat, producing complete dispersion and gelatinization of starch, in comparison to fire roasting.     

Buckwheat groats production. Part I. The changes in carbohydrates and protein of buckwheat (Fagopyrum esculentum Moench) during processing

The changes in carbohydrates and protein of buckwheat during groats production were investigated. The influence of cleaning, dehulling and in particular two different systems of roasting on the buckwheat compounds were also discussed. It was found that processing of buckwheat was responsible for the changes in most factors studied regarding particular proteins and cellulose. During the roasting process temperature activity as well as the influence of water or steam created significant changes in the solubility of proteins. More pronounced changes in chemical composition were observed after steam roasting in comparison to fire roasting.     

The influence of organic and conventional crop management,variety and year on the yield and flavonoid level in common buckwheat groats

Common buckwheat (Fagopyrum esculentum Moench) is a pseudocereal that is cultivated for its achenes that possess a high level of flavonoids. Some scientific studies have found that the growing conditions can significantly affect the flavonoid content in conventional and organic food products. Hence, the present study compared conventionally and organically produced common buckwheat with respect to the content of selected flavonoids, thousand achenes weight and achene yield. Three buckwheat varieties were grown with organic and conventional crop management under the same environmental conditions. The thousand achenes weight and achene yield were not significantly influenced by way of crop management. The level of rutin, epicatechin, catechin, and epicatechin gallate in buckwheat groats (hulled achenes) were quantified with high pressure liquid chromatography. Only rutin and epicatechin gallate reached significantly higher level in organic groats. However, the differences were influenced by environmental conditions in the given year and variety.     

Moisture dynamics of thermally treated poplar plywood

The present study analyzes the moisture dynamics of thermally treated poplar plywood heated to 170, 190 and 210 °C through a thermo-vacuum process. The water absorption coefficient and the residual moisture content were determined using the floating and submersion methods (prEN 16818). Thermally treated poplar plywood was less reactive within the hygroscopic field, while it absorbed a higher amount of water beyond the fibre saturation point and maintained a higher moisture content at the end of the absorption/desorption cycle.     

Amaranth protein films from thermally treated proteins

The usefulness of amaranth protein isolates, native and thermally treated, in edible films preparation was studied. Protein films were prepared by casting using glycerol as plasticizer. Films from amaranth native protein isolates showed low water vapor permeability (WVP) but poor mechanical properties. In order to improve this functionality, proteins were treated at 70 and 90 °C which corresponds to the denaturation temperature of the protein fractions present in the isolates. The unfolded conformation of these thermally treated proteins, when partially or totally denatured, favors the interactions between polypeptide chains during the film formation. These interactions lead to a greater cross-linking degree, which was reflected in the lower amount of water-soluble free peptides that were linked to the matrix. In these thermally treated protein films, a greatest contribution of disulfide and hydrogen bonds to the films stabilization was observed. These changes in the films structural properties would confer them a greater tensile strength and lower water solubility but higher thickness and WVP.     

Artificial groats from rice-processing by-products

Broken rice and rice dust middlings are valuable raw materials to be used in food industry. The protein content increases in the following succession: white rice < broken rice < rice dust middlings. The content of lysine and sulfur-bearing amino acids in protein increases in the same order. The rice dust middling protein substantially differs from white rice protein by its fractional composition. This protein is balanced with regard to all essential amino acids except tryptophane. The method is developed to process broken rice and rice dust middlings into artificial groats. Casein is added to increase groat biological value. The broken rice groats possess good technological properties. Meals made from these groats have organoleptic properties similar to the properties of natural rice. The rice dust middling groat have inferior technological properties as compared to the broken rice. The biological value of artificial groats is much higher than that of natural rice. In these aspects they are similar to or even better than casein.     

The fate of recombinant DNA in thermally treated fermented sausages

 The fate of recombinant DNA (rDNA) from genetically modified starter organisms in thermally treated fermented sausages (Kochsalami) was monitored by a polymerase chain reaction (PCR)-based estimation of the concentration of the rDNA. We defined an rDNA titre as the smallest volume of the DNA solution which still results in a detectable amplicon on PCR. In sausages a degradation of the rDNA was observed during storage. However, this did not proceed so far that rDNA was no longer detectable after 9 weeks of incubation. It was observed that the rDNA is strongly protected against the activity of DNase I in the meat matrix. To include the aspect of release of rDNA from genetically modified starter organisms into the meat matrix, Kochsalami-type sausage was produced with the aid of recombinant strains of Lactobacillus curvatus as starter organisms. It was shown that only a minute part of the rDNA contained in the starter organisms can be recovered from the meat matrix by extraction as "free" DNA. To recover the total rDNA, cell wall lytic enzymes were necessary. No significant effect on the detectability of the rDNA was observed on variation of the ecological factors prevailing during the production and storage of the sausages, such as the temperature of thermal treatment, pH and fat content. The concomitant presence of Staphylococcus aureus (>10⁶ cfu/g) producing heat-stable nuclease did not affect the detection of the rDNA. Received: 29 March 1999     

Superheated steam processing of oat groats

Superheated steam (SS) processing of oat groats with a lab-scale SS processing system was studied as a method of heat treatment alternative to commercial processing (kiln drying) of groats. The objective of this study was to determine conditions of SS processing necessary to obtain groats with inactivated peroxidase, moisture content and colour comparable to commercially processed groats, but with pasting properties unique to those obtained in commercial processing. Raw or moisture tempered oat groats (∼13 g) were processed with SS at varying processing times (1-30 min) depending on steam temperature (110-160 °C) and velocity (0.35 and 1.00 m/s) used. Generally, groats processed with SS exhibited higher cold paste (64 °C) viscosity than the groats processed commercially. Oat groats processed with SS to final moisture content of 9-10/100 g (wet basis, wb) or less were peroxidase negative. The parameters of SS selected for processing of oat groats were: temperature of 110 °C, a velocity of 1.00 m/s, and two processing times (10 and 14 min). These parameters gave groats with inactivated peroxidase, moisture content at ∼9.5/100 g (wb), significantly (P < 0.05) brighter colour, and significantly higher cold paste viscosity compared to that of groats processed commercially.     

Characteristics of commercially heat-treated oat groats

Oat groats, sampled at various steps in the commercial production of oat flour, were examined to determine the effects of heat treatment on oat quality. The samples were: original cleaned milling oats, conditioned groats, dried groats and cutmeal. The amount of oat protein solubilized by different concentrations of sodium dodecanoate was indicative of the degree of heat treatment received during processing. Pasting characteristics of conditioned groats were lower than those of other oat samples. Dry groats and cutmeal samples had similar protein solubility and pasting characteristics. Lipase activity of grain samples, except cutmeal, were lower than those of flours obtained from them; that of dried groats was negligible. Differences were observed in the three endothermic transitions (starch, protein and amylose-lipid complex) in the differential scanning calorimetry (DSC) thermograms of oat samples.     

Effect of oil-soluble emulsifiers on solidification of thermally treated creams

The effects of addition of an oil-soluble emulsifier on cream solidification after the thermal treatment, in which the cream was temporarily heated and then cooled, were investigated. Thirteen oil-soluble emulsifiers were tested for the ability to retard the cream solidification. Two emulsifiers, namely the sucrose esters of fatty acids that have low hydrophilic–lipophilic balance (HLB) values (SE-L) and the citric acid esters of monoglyceride (CMG), showed an inhibitory effect on the cream solidification. The increase in solid fat content (SFC) in cream was delayed by SE-L addition during the recooling process in the thermal treatment. SE-L inhibited the cream solidification presumably by modifying the fat crystallisation behaviour in oil droplets. On the other hand, the SFC changing pattern of the cream containing CMG during the recooling process was not different from that of solidified cream, suggesting that a mechanism other than fat crystallisation was involved in the inhibition of the cream solidification by this emulsifier.     

The analysis of phenolic constituents in glabrous canaryseed groats

Nineteen glabrous canaryseed samples, comprising brown- and yellow-coloured seeds, were investigated to determine the nature of phenolic constituents present. Total phenolic content (TPC) was determined, using the Folin–Ciocalteau assay. Flavonoid and phenolic acid compositions were determined, using high performance liquid chromatographic and mass spectrometric (LC–MS/MS) techniques. TPC ranged from 174 to 209 mg/100 g for canaryseed wholemeal samples. The canaryseed bran contained twice as much TPC as the wholemeal. The brown- and yellow-coloured whole canaryseeds exhibited the same flavonoid profiles. LC–MS/MS analysis showed that the canaryseed acetone extract was rich in flavonoid glycosides, with the bran being mainly composed of O-pentosyl isovitexin and the flour having a compound at m/z 468. No proanthocyanidins were detected in the 19 samples. Ferulic acid was the dominant phenolic acid, followed by caffeic and p-coumaric acids. The wholemeal obtained from the brown-coloured group had significantly higher contents of ferulic (>196 mg/kg) and caffeic (>96 mg/kg) acids in comparison to the yellow-coloured canaryseed group. The latter had ferulic and caffeic acids at levels less than 165 and 78 mg/kg, respectively, with one exception which had relatively higher levels (190 and 94 mg/kg). Whilst canaryseed flour contained significantly very low levels of ferulic acid (22–34 mg/kg), the bran was enriched in ferulic (593–766 mg/kg), caffeic (304–452 mg/kg) and p-coumaric (119–142 mg/kg) acids.     

荞麦和商品苦荞茶中总黄酮的含量测定

目的:测定荞麦不同栽培种、植株不同部位以及不同商品苦荞茶中的总黄酮含量。方法:采用UV法测定总黄酮含量;通过回流法提取,NaNO3-Al（NO3）3法显色测定样品吸光度,以芦丁为标准溶液计算求得总黄酮含量。结果:芦丁在0.003006⁰.1503mg/mL浓度范围内线性关系良好,R2=0.9999;平均回收率为97.9%,RSD为1.95%。结论:不同栽培种荞麦总黄酮含量测定中,苦荞的总黄酮含量在13.67²1.56mg/g之间,甜荞总黄酮含量在5.79⁷.23mg/g之间,苦荞总黄酮含量总体高于甜荞;荞麦植株不同部位中叶的总黄酮含量最高,最高达到68.30mg/g;商品苦荞茶中,所测商品总黄酮含量在6.96¹6.78mg/g之间,较苦荞种子中总黄酮含量有一定程度减少。该方法简便快捷,结果准确,重现性好,适用于荞麦和商品苦荞茶中总黄酮含量的测定。      

燕麦籽粒硬度与品质特性关系研究

为考察燕麦籽粒硬度与品质特性之间的关系,收集国内5个燕麦主产区56份燕麦样品,检测了燕麦籽粒硬度与主要营养成分(蛋白质、脂肪、直链淀粉、β-葡聚糖等)含量及理化特性(白度、糊化特性)指标,并分析了这些参数间的相关关系。结果表明,燕麦籽粒硬度值在17.29~58.70 N范围内,均值为38.32N,燕麦类型(皮或裸)、品种、产地等因素均对其有重要影响。籽粒硬度与蛋白质、灰分、a*值、峰值黏度、最小黏度呈极显著相关关系,与L*值、衰落值、糊化时间呈显著相关关系。