稳定化全麦粉的品质评价

对稳定化全麦粉的水分、灰分、湿面筋、降落指数、粗蛋白、粗脂肪、总膳食纤维、可溶性膳食纤维、烷基间苯二酚、总酚、B族维生素、矿物元素、总抗氧化值、脂肪酸值、储藏稳定性等品质指标进行分析研究。结果表明,稳定化全麦粉的灰分、总膳食纤维、总抗氧化值、B族维生素及矿物元素指标高于普通小麦粉2～5倍,烷基间苯二酚含量达10倍多,其他指标与普通小麦粉相当。全麦粉储存4个月后,其脂肪酸值仍满足小麦粉的中国国家标准要求。稳定化全麦粉相比于普通小麦粉具有更好的营养价值。     

几种添加物对全麦湿面蒸煮品质和感官品质的影响

以麦麸、小麦胚芽和小麦粉为原料制作全麦面条,比较不同食品添加剂(食盐、谷朊粉、黄原胶)对全麦湿面品质的改良效果,并考察不同添加剂之间的复配效果。结果表明:食盐、谷朊粉和黄原胶均可以改善面条的蒸煮品质并提高全麦面条的感官评分,其中食盐的最适添加比例为1%~2%,谷朊粉的最适添加比例为1.5%~2.5%,黄原胶的最适添加比例为0.15%~0.2%,两种或者三种添加剂经过复配后面条的品质要明显好于单独添加一种添加剂,其中黄原胶和食盐的复配对降低面条的蒸煮损失率效果最明显,三种添加剂复配之后感官评分最高。     

挤压处理对麸皮、胚芽及全麦粉品质的影响研究

研究了全麦粉稳定化加工过程中挤压热处理对麸皮与胚芽的脂肪酸值、烷基间苯二酚、B族维生素、植酸、总酚、总抗氧化值等品质指标的影响。结果表明,挤压处理能有效地降低麸皮和胚芽的脂肪酸值,提高其抗氧化活性;有利于提高全麦粉的储藏稳定性;同时有利于保留麸皮与胚芽中的生理活性组分,很好的保持全麦粉的营养价值。因此,挤压加工是一种有效的全麦粉稳定化处理工艺。      

Susceptibility of the saw-toothed grain beetle, Oryzaephilus surinamensis (L.), to gamma radiation

Gamma radiation was applied over the range of 25–125 Gy at five dose levels against 7–10-day-old adults of Oryzaephilus surinamensis, and the sterility and mortality effects were investigated. All experiments were carried out in incubators maintained at 27 ± 0.5 °C and 70 ± 5% relative humidity. The results obtained revealed that the percentage of adults surviving was dependent on the dose level. There were no beetles left alive and no progeny produced when adults were exposed to 125 Gy. LD₅₀ and LD_99.9values were determined to be 55.6 and 216.4 Gy respectively; the sterilizing dose levels (SD₅₀ and SD_99.9) were estimated to be 26.2 and 117.1 Gy respectively.     

我国全麦食品品质改良研究进展

全麦食品含有丰富的不饱和脂肪酸、膳食纤维、高活性酶以及酚类和多糖类活性物质,使其食用价值和营养价值远高于常规面制品。因其特殊的化学组成,若完全依照常规面制品的加工方式进行加工,制得的全麦食品存在食用品质不佳和耐储藏性较差等问题。因此,在尽可能保持全麦食品原有营养成分的前提下,如何提高其食用品质和耐储藏性俨然成为我国全麦食品产业所面临的首要问题。综述近年来我国全麦食品的品质改良方法及研究进展,为我国全麦食品的进一步研究开发提供参考依据。     

Effects of gamma radiation on microbial,physicochemical, and structural properties of whey protein model system

Gamma radiation has been used in food processing for many years, though it has certain effects on food components. Whey protein solutions (10%/30%, wt/vol) were treated with gamma radiation at various dosages (10–25 kGy) and evaluated for microbial changes in the solutions and physicochemical and structural changes of whey proteins. Whey protein solutions after gamma radiation showed substantially lower populations of all viable microorganisms than those of controls. The 10% whey protein solution treated at radiation of 20 or 25 kGy remained sterile for up to 4 wk at room temperature. Gamma radiation increased viscosity and turbidity and decreased soluble nitrogen of whey protein solutions compared to nonradiated control samples regardless of radiation dosage. Nonreducing sodium dodecyl sulfate-PAGE suggested that whey proteins under gamma radiation treatment formed aggregates with high molecular weights. Reducing sodium dodecyl sulfate-PAGE showed that disulfide bonds played a role in gamma radiation-induced whey protein cross-linking. Scanning and transmission electron microscopy micrographs exhibited large aggregates of whey proteins after gamma radiation treatment. Results suggested that gamma radiation could be applied to whey protein solution for purposes of reducing microbial counts and cross-linking protein molecules.     

Inherited sterility in Mediterranean flour moth Ephestia kuehniella Zeller (Lepidoptera: Pyralidae): Effect of gamma radiation on insect fecundity, fertility and developmental period

The effects of gamma radiation on the fecundity, fertility, longevity, development and level of inherited sterility in the Mediterranean flour moth Ephestia kuehniella were determined. Newly emerged virgin Mediterranean flour moth adults were irradiated with 100, 200, 400 and 600 Gy in a ⁶⁰Co irradiator with a source strength of ca. 3811 Ci and a dose rate of ca. 1 Gy/min. Laboratory studies revealed that radiation did not effect the longevity of irradiated male and female adults. Inherited deleterious effects of gamma radiation were observed in the F₁ and F₂ generations. Fecundity and the daily egg laying pattern of irradiated and unirradiated females mated to irradiated males was not significantly different from untreated controls. Adverse effects of gamma radiation were observed in the percentage egg hatch and rate of development. Levels of sterility in the P₁, F₁ and F₂ generations were higher than that of untreated controls. The doses of radiation also had a significant effect on the time from oviposition to larval eclosion or adult emergence. Mortality increased with radiation dose. The incidence of larval and pupal mortality was higher in the F₂ than in the F₁ generation.     

麸皮粗细度对全麦粉挂面品质的影响

探讨了经稳定化处理的不同粗细度麸皮对全麦粉挂面品质及其储藏稳定性的影响,结果表明:随着麸皮粗细度的减小,全麦粉挂面表面光滑度增加,硬度变大,L*降低、a*值和b*值升高,达到显著性水平(P0.05);不同麸皮细度的全麦粉挂面蒸煮品质无显著性变化;适宜制作优质全麦粉挂面的麸皮粗细度范围为≥80目;随着储藏时间的延长,全麦粉挂面酸度值不断上升。储藏八个月时,酸度值在3.33~3.75 m L/10 g之间,满足《花色挂面》标准的要求。     

糯米粉储藏特性的研究

研究了糯米粉在20℃、25℃、30℃及35℃温度下,以真空、CO2气体封入、N2气体封入、自然空气封入4种包装(气体)条件下,储藏6个月,分析糯米粉储藏品质的变化情况。结果表明,储藏温度越高,糯米粉品质劣变越严重,60d为最佳储藏期限。在高温35℃条件下气调储藏组(真空、CO2气体封入、N2气体封入)较常规储藏(自然空气封入)对糯米粉储藏品质的劣变起到抑制作用,但不同气调储藏方式对糯米粉储藏品质影响的差异不明显。     

Influence of processing on the extension of shelf-life of Nagli-fish (Sillago sihama) by gamma radiation

Studies were carried out to evaluate the microbiological profile, shelf-life and quality of Nagli fish (Sillago sihama) subjected to gamma irradiation. Non-irradiated samples were unacceptable organoleptically after 7–8 days of storage at 1–2°C while irradiated samples (2 and 3 kGy) were acceptable up to 19 days. Dressing prior to irradiation had no additional advantage to shelf-life over whole fish. Total bacterial count (TBC), total volatile basic nitrogen (TVBN), trimethylamine (TMA) and sensory evaluation data revealed no significant differences between whole and dressed fish. Salmonella sp. were not detected in 3 kGy-irradiated samples whereas 2 kGy destroyed Vibrio parahaemolyticus and Staphylococcus aureus. Listeria monocytogenes and Yersinia enterocolitica were not detected but non-pathogenic species such as L. grayi, L. murrayi, and Y. tuberculosis were present in the fish prior to irradiation. Irradiation doses of 2 and 3 kGy destroyed Yersinia sp. and Listeria sp., respectively. These organisms were not detected during storage of the treated fish.     

Effect of gamma radiation on ochratoxin production by the fungus Aspergillus ochraceus

Mycelial discs of the fungus Aspergillus ochraceus NRRL 3174 were exposed to gamma irradiation and then incubated on synthetic medium (SM). Growth rate, mycelial dry weight and ochratoxin production were measured. A delay in mycelial growth of 24 and 48h over the control occurred following irradiation of mycelial discs with 150 and 200 krad, respectively. No growth occurred from discs exposed to 300 krad. An increase in ochratoxin production occurred on the SM from cultures developing from discs of mycelium which had been irradiated with 50, 100, 150 and 200 krad. The amount of toxin produced was 3500, 4100, 3200 and 3000 ng per plate, respectively, as compared with 2800 ng per plate produced by the control. Exposure of mycelial discs to a temperature of 40°C for 15 and 30 min prior to treatment with 200 krad resulted in complete inhibition in mycelial growth. No growth inhibition or notable change in ochratoxin production was recorded when the mycelial discs were exposed to 25, 50 or 100 krad after the heat treatments. Pure ochratoxin was found to be stable even at 7.5 mrad, and no reduction in its fluorescence intensity under u. v. light was recorded following that dose.     

马铃薯全粉加工制品及营养价值研究进展

综述了马铃薯全粉的营养价值以及在各类食品中的应用,对马铃薯全粉研究利用和发展前景进行了展望。     

高筋小麦粉储藏技术的研究

以高筋小麦粉为研究对象,通过模拟在不同温度(15、25、35℃)、不同储藏方式(充N2、脱氧剂脱氧、真空、对照)下储藏高筋小麦粉,研究了储藏期间高筋小麦粉脂肪酸值、降落数值、湿面筋、面筋指数的变化规律。结果表明:高筋小麦粉的脂肪酸值、降落数值、湿面筋以及面筋指数都能较好地反映出高筋小麦粉储藏品质的变化。总体变化趋势表现为:随着储藏时间的延长,脂肪酸值和降落数值升高,湿面筋含量和面筋指数下降。在储藏期间温度的变化是最主要的影响因素,低温有延缓品质劣变的优点;其次为储藏方式,但相互之间差别不明显;同时发现气调储藏在高温环境中效果较好,所以高筋小麦粉应尽量保存在低温气调储藏条件下。     

Effect of gamma irradiation on the color properties of synthetic fabrics dyed by arylazo-pyrazolone disperse dyes

Two derivatives of 3-amino-4-arylazo-1-phenylpyrazol-5-one have been used for dyeing un-irradiated and irradiated polyester and nylon fabrics using different absorbed doses of Co-60 gamma irradiation to study the effect of radiation treatment on the color strength of dyed fabrics. The data color report is used for the evaluation of un-irradiated and irradiated dyed polyester and nylon using GretagMacbeth spectrophotometer (CE 7000a) in CIE Lab system. The color strength K/S of the dyed polyester and nylon fabrics was increased by increasing the absorbed dose to 80 kGy. It is found that gamma irradiation has a potential to improve the fastness properties such as light, rubbing, perspiration, and washing.     

Inactivation of A. ochraceus spores and detoxification of ochratoxin A in coffee beans by gamma irradiation

Ochratoxin A (OTA) produced in food by Aspergillus ochraceus is known to cause adverse health effects. Among the plantation products, green coffee beans are prone to fungal attack and get contaminated with OTA frequently. A fungal strain isolated from green coffee beans was characterized by morphological analyses as well as internal transcribed spacer (ITS) and 5.8S rDNA sequencing, turned out to be A. ochraceus, however, nontoxigenic. Hence, additional strains of A. ochraceus were procured and characterized for toxin production. Presterilized green coffee beans were spiked with a toxigenic strain and treated with gamma radiation. Minimum inhibitory dose (MID) of gamma radiation for 10(4) and 10(8) spores of A. ochraceus strain per 10 g of green coffee beans was found to be approximately 1 and approximately 2.5 kGy, respectively. The radiation treatment (10 kGy) almost degraded the preformed or in vitro added OTA (50 ppb) in coffee beans. OTA degradation was found to be enhanced with increase in moisture content. Cytotoxicity in terms of cell viability was found to be reduced significantly for radiation treated OTA in MTT [3-(4,5-dimethylthiazole-2yl)-2,5-diphenyl tetrazolium bromide] assay as well as flow cytometric analysis when studied using human intestinal epithelial (Int-407) cells. Similar finding was also observed with E. coli MG1655 cells. Thus the inclusion of gamma radiation treatment in the postharvest processing chain of green coffee beans could help in eliminating toxigenic fungi as well as destroying preformed OTA without affecting the sensory attributes. PRACTICAL APPLICATION: In general, mycotoxins including ochratoxin A (OTA) are highly stable to detoxifying agents. Green coffee beans are prone to fungal attack and could get frequently contaminated with the OTA due to improper drying or rehydration during storage. Gamma radiation processing of green coffee beans was found to eliminate the A. ochraceus spores as well as inactivate OTA without affecting its sensory attributes. Thus inclusion of gamma radiation in the postharvest processing chain of green coffee beans would be very useful for consumer safety and coffee trade.     

Effect of extrusion on nutritional quality of maize and Lima bean flour blends

Maize flour (Zea mays) (M), Lima bean flour (Phaseolus lunatus) (B) and blends of these in proportions of 75M/25B, 50M/50B and 25M/75B (w/w) were extruded and their nutritional quality evaluated. Extrusion was done with a single screw extruder at 160 °C, 100 rpm and 15.5% moisture. In vitro protein digestibility (87%) was higher in the extruded products. Available lysine and resistant starch were highest in 50M/50B raw flour (59.5 g kg⁻¹ protein, 67.9 g kg⁻¹, respectively) but decreased after extrusion (45.5 g kg⁻¹ protein, 16.6 g kg⁻¹, respectively). The same treatment had the lowest available starch (561.6 g kg⁻¹ flour, 507.9 g kg⁻¹ extrudate). Total dietary fiber in the 50M/50B raw flour blend was 144 g kg⁻¹ versus 176 g kg⁻¹ in its extrudate. This was most noticeable for soluble dietary fiber, which increased from 10.6 g kg⁻¹ to 79.4 g kg⁻¹ after processing. Extrusion of blends is feasible up to a 50% bean inclusion level, which improves the nutritional value of the expanded product.Copyright © 2006 Society of Chemical Industry     

Qualitative changes in Pleurotus ostreatus (Jacq.: Fr.) Kumm. mushrooms resulting from different methods of preliminary processing and periods of frozen storage

BACKGROUND: The aim of this study was to investigate the effect of different methods of preliminary processing and periods of frozen storage on the quality of Pleurotus ostreatus (Jacq.: Fr.) Kumm. mushrooms. In pre‐processing, mushrooms were blanched or soaked and blanched in water as well as in aqueous solutions of citric acid, L ‐ascorbic acid and/or lactic acid. During 12 months of storage at ?25 °C, sensory evaluations, instrumental colour measurements and chemical analyses of the frozen products were carried out every 4 months. RESULTS: The greatest changes resulting from technological treatment were found in flavour. At the end of the storage period the content of thiamine and riboflavin decreased by 14–65% and 3–13% respectively compared with the raw material. This was accompanied by changes in total acidity and vitamin C content within the ranges ? 56 to + 61% and ? 97 to + 5% respectively. CONCLUSION: Based on the results of the sensory evaluation, a maximum storage period of 4 months was set for the frozen product obtained from unblanched mushrooms. Mushroom products pre‐processed in aqueous solutions with added substances may be stored for 8 months and those blanched in water for 12 months. Copyright © 2009 Society of Chemical Industry