Degradable Wheat Gluten Films: Preparation, Properties and Applications

Degradable films from spray-dried (SD) and flash-dried (FD) wheat gluten prepared at various pHs, salt levels, temperatures, and shearing times were compared. Differences were observed in properties of the films related to processing conditions. Films prepared from SD wheat gluten were thicker, and had higher tensile strengths and Young's moduli. SD wheat gluten solutions applied as coating material resulted in Grade A-quality shell eggs maintaining quality for 30 days at room temperature. Additionally, SD wheat gluten coating increased the water stability of starch-based packaging.     

麦草浆甲醇强化氧气漂白的研究

进行ＡＳ－ＡＱ麦草浆甲醇强化的氧气漂白研究，结果表明：漂前的硫酸预处理是提高氧漂浆质量的重要措施；在实验条件下，甲醇用量和氧气初压是决定漂浆白度的最主要因素；温度对漂浆得率的影响较大；温度太高，将对漂浆白度不利；漂白时间对漂浆白度、得率的作用较小。在选定的６％甲醇、９０℃、８０分钟、０．７ＭＰａ氧气初压的条件下，氧漂浆白度为７３．４％ＳＢＤ；再经１．５％Ｈ２Ｏ２漂白，浆白度达８２％ＳＢＤ，裂断长为     

稻草AS－AQ法制浆的研究

对稻草ＡＳ－ＡＱ法蒸煮中不同亚硫酸化度的影响进行了研究。结果表明，在其他条件不变的情况下，随着亚硫酸化度的降低，木素脱除率增高；另一方面，蒸煮的脱木素选择性降低，碳水化合物溶出率升高而得率下降。在亚硫酸化度０．３～０．４处，纸浆的硬度最低。未漂浆白度随亚硫酸化度降低而降低，漂率随其降低而升高。     

小麦胚芽蛋白提取工艺的研究

通过正交试验研究了麦胚蛋白质的提取工艺,试验结果表明,提取小麦胚芽蛋白质的最佳工艺条件是：pH值10,提取时间60min,温度45℃,料液比为1：16;在最佳条件下小麦胚芽蛋白的提取率为42.74％。     

小麦麸皮戊聚糖的润肠通便效果研究

对小麦麸皮不同组分的润肠通便效果进行研究,发现小麦麸皮碱溶戊聚糖组分(AEP)具有较好的润肠通便效果,而水溶戊聚糖组分(WSP)和剩余麸皮残渣(AEP-R)的润肠通便效果较差.这说明小麦麸皮中起润肠通便作用的是其中的戊聚糖组分,并且戊聚糖的润肠通便效果与其溶解性有关,溶解性较差的组分具有较好的润肠通便效果,水溶性较好的组分润肠通便效果较差.     

Insecticidal effect of Steinernema feltiae (Filipjev) (Nematoda: Steinernematidae) against Tribolium confusum du Val (Coleoptera: Tenebrionidae) and Ephestia kuehniella (Zeller) (Lepidoptera: Pyralidae) in stored wheat

The confused flour beetle, Tribolium confusum, and the Mediterranean flour moth, Ephestia kuehniella, are important pests of stored grain products. The insecticidal effect of three strains (UK 76 [=Nemasys], USA/SC, and Hawaii) of the entomopathogenic nematode Steinernema feltiae was determined in the laboratory, in wheat, against these pests. The nematodes were applied at three dose rates: 100, 300 and 900 nematodes/insect individual. The Hawaii strain was most virulent against T. confusum adults and larvae, with a significant dose effect in the case of the larvae. Larval mortality of this species reached 79% and 100% after 7 and 14 d of exposure to the nematodes, respectively, at the highest dose applied. On the other hand, adult mortality of T. confusum did not exceed 66%. In the case of E. kuehniella larvae, USA/SC performed best causing 52% and 69% mortality after 7 and 14 d exposure, respectively, at the highest dose tested. Since very few data are available on the effect of entomopathogenic nematodes against these pests, it is concluded that the Hawaii and USA/SC strains of S. feltiae should be further investigated as promising biological control agents for T. confusum and E. kuehniella.     

麦胚稳定化处理方法的比较研究

研究了热风干燥、微波干燥、常压蒸气和高压蒸气处理麦胚对其加速储藏期间脂肪酶的钝化效果.在38℃下进行35 d的加速储藏试验,并跟踪检测,以酸值和过氧化值作为钝化脂肪酶的表征参数,对不同方法处理原料的优化结果(酸值和过氧化值)进行了比较.结果表明,脂肪酶的钝化效果:湿热蒸气处理的效果优于微波干燥、明显好于热风干燥处理,酸值和过氧化值均上升缓慢,常压蒸气处理20 min即可达到预定效果.对常压蒸气处理的麦胚原料进行超临界萃取并对得到的麦胚油进行了GC分析,与对照组原料相比,脂肪酸组成与含量均无明显变化.水蒸气是良好的热载体和传热介质,蒸气处理能够有效钝化脂肪酶的活力,提高小麦胚的贮藏稳定性.     

The effect of cooking on proteins from acha (Digitaria exilis) and durum wheat

The effect of cooking on proteins from acha and durum wheat was assessed from an analysis of protein extractability, gel electrophoretic profiles, in-vitro protein digestibility (IVPD) and the amino acid compositions of wholemeal flour and residue proteins. Heating wholemeal flour samples at 100–140°C (t = 10–40 min) resulted in 0–30% and 45–55% decreases in acha and durum protein solubility, respectively. In general, high molecular weight (30–70 k Da) protein subunits were more susceptible to heat damage. For both cereals, sodium dodecyl sulphate (SDS; 10 g litre^?1) and/or dithiothrcitol (DTT; 10 mM ) increased protein solubility in unheated and heated samples. The IVPD index was 90–91% and was not significantly altered by cooking (100–120°C, t = 40 min). Cooking at extreme temperatures (140°C, t = 40 min) reduced the IVPD by 8% (P = 0.05). Osborne fractionation resulted in a durum or acha residue level of 7.8% or 55.2%. Treatment with solvent containing propanol, SDS and/or DTT at room temperature followed by SDS-polyacrylamide gel electrophoresis of non-solubilised proteins showed that the glutelin fraction of acha, with the exception of a 65 kDa subunit, was insoluble owing to strong inter-subunit hydrophobic and disulphide interactions. Wholemeal acha flour and residue protein showed a significantly greater level of hydrophobic and sulphur amino acids as well as glutamine which is associated with H-bonding. The possibility that cereal protein solubility is also dependent on protein-carbohydrate links is discussed.     

Isolation and partial characterisation of two low molecular weight durum wheat (Triticum durum) glutenins

Two low molecular weight durum wheat (Triticum durum Desf) glutenins, DSG-1 and DSG-2 (durum-wheat sulphur-rich glutenin fractions) were isolated from two cultivars, Mondur of good technological quality and Kidur of poor technological quality. The glutenin fraction, composed mostly of DSG protein, was extracted using a low concentration of NA-tetradecanoate and then fractionted by by using molecular sieve chromatography (Bio-Gel P 30). The amino acid compositions and the N-terminal sequences of the pure DSG proteins were determined, and their hydrophobic characteristics, calculated on the basis of these data, showed that DSG-2 is more hydrophobic than DSG-1. The amino acid compositions of DSG-1 and DSG-2 were different. The N-terminal amino acids of DSG-1 and DSG-2 were also different but were identical for each of the two cultivars. In the case of DSG-1, in addition to the main chain a minor chain was found in which the first three amino acids of the main chain were missing. The minor chain represented about 30% int he DSG-1 of mondur and almost 50% in Kidur.     

Rheological Properties Including Tensile Fracture Stress of Semolina Extrudates Influenced by Moisture Content

Semolina extrudates were reshaped, immediately after extrusion to form 0.5 mm thick × 2 mm wide × 130 mm long strips. Moisture content (W) was adjusted to 5 to 39% (dry basis) equilibrating in desiccators containing saturated salt solutions. The following tensile rheological properties of the prepared samples were determined at room temperature (21-24°C) using a Rheometrics solid analyzer: Young modulus (E), yield stress (σ_y), fracture stress (σ_c) and fracture stain (?_c). Each of E, σ_y and σ_c was fitted by a semilogorithmically linear function of W with a negative slope. The property ?_c fitted two semilogarithmically linear functions: for W < 24.2% a line with a positive slope and for W > 24.2% a line with near zero slope. Such data for moisture ranges used in conventional pasta drying can help to optimize conditions for pasta production without stress cracking.