扬麦系列小麦品种的饼干品质分析

为了解扬麦系列小麦品种的饼干加工品质,明确弱筋小麦育种程序中简单实用的品质评价指标,以26个扬麦系列小麦品种为试验材料,测定其籽粒和面粉的理化品质及其曲奇和酥性饼干的品质,并进行理化品质与饼干品质的相关性分析。结果表明,26个扬麦小麦品种曲奇饼干的直径为15.03～18.50 cm,厚度为15.99～23.10 mm、直/厚比为0.66～1.14;酥性饼干的硬度为522.66～1520.00 g,脆性为36.30～38.82 mm,感官评分为81.81～84.29分。根据饼干品质评价,26个扬麦小麦品种可被分为三类:第一类为扬麦10号、扬麦158等6个中强筋品种,曲奇饼干直径小、厚度大、直/厚比小,酥性饼干的硬度大、感官评分相对稍低;第二类为扬麦9号、扬麦13等14个弱筋品种,曲奇饼干直径大、厚度小、直/厚比大,酥性饼干硬度小,感官评分高;第三类为扬麦4号、扬麦6号等6个品种,曲奇和酥性饼干品质介于上述两类之间。相关性分析表明,碳酸钠溶剂保持力(solvent retention capacity, SRC)、水SRC、乳酸SRC、蔗糖SRC、吸水率、籽粒硬度、SDS沉淀值与曲奇饼干的直径、直/厚比和酥性饼干感官评分呈极显著负相关,而与曲奇饼干的厚度、酥性饼干的硬度和脆性呈极显著正相关。综合曲奇和酥性饼干品质,26个扬麦系列多数小麦品种的饼干品质较好,以扬麦9号、扬麦13、扬麦15、扬麦20、扬麦24表现最为突出;扬麦158、扬麦10号、扬麦16、扬麦17、扬麦23、扬麦28的饼干品质相对稍差;籽粒硬度、粉质仪吸水率、SDS沉淀值、碳酸钠SRC、乳酸SRC、水SRC和蔗糖SRC是评价弱筋小麦的关键指标。     

茉莉花茶增湿窨制新工艺的效果

用喷水增湿茶坯的方法窨制的茉莉花茶,结果表明,一窨花茶的品质,茶坯含水量10%—20%处理均优于传统工艺。将特级烘青茶坯含水量增加到10±2(%)、同时减花20%或30%,进行连窨试验,结果表明,减花二窨一提的花茶品质均优于传统工艺(不减花四窨一提)花茶,其中尤以减花30%二窨一提和不减花、茶坯不烘焙直接三窨一提处理的最佳。与传统工艺比较,新工艺不仅节省了花量,而且减少了窨次及烘焙次数,大大缩短了窨花周期(由12d 以上缩至4d),经济效益十分显著。     

Canopy damage to conifer plantations within a large mixed-severity wildfire varies with stand age

The 2002 Biscuit Fire burned at mixed-severities encompassing over 200,000 ha of publicly owned forestland, including more than 8300 ha of conifer plantations. We used pre- and post-fire digital aerial photography to examine how the level of canopy damage varied within these plantations in relation to topography, weather, vegetation-cover, and management history, with an emphasis on the age of the plantation. We examined 198 plantations that varied widely in age (5-47 years), size (1.25-47 ha), and landscape context. The average level of canopy damage within the plantations was 77%. Based on Random Forest variable importance values, plantation age was the best predictor of canopy damage. Average annual precipitation, elevation and topographic position were ranked second, third, and fourth, respectively. A model selection procedure, using geo-statistical regression models and Akaike’s information criterion, corroborated the importance of plantation age relative to the other predictors tested and also suggested that the influence of age varied over time. The top ranked regression model indicated that the level of canopy damage reached its maximum around age 15 and stayed relatively high until age 25 before declining.     

Effect of sesame seed flour on millet biscuit characteristics

Defatted sesame seed flour replaced millet flour at 30, 40, and 50% and was used to prepare biscuits. Protein content of the biscuits was significantly (p 0.05) increased by replacement with sesame seed flour. Millet flour biscuits were heavier than those from the blends. Diameters and weights of biscuits were reduced and thicknesses and spread factors were increased with increasing level of sesame replacement. Sensory evaluation results showed that the biscuits were highly rated for flavor and crispiness but considered poor in color.     

不同品质类型小麦戊聚糖含量及其与品质的关系

为给小麦品质的遗传改良提供依据,选用不同品质类型的7个小麦推广品种和1个密穗小麦,研究了戊聚糖含量及其与品质的关系.结果发现,中强筋小麦品种具有比弱筋小麦品种更高的戊聚糖含量,且不同筋力的推广品种戊聚糖含量表现出较大差异.弱筋小麦的水溶性戊聚糖含量与延展性、饼干直径呈极显著和显著负相关;非水溶性戊聚糖、总戊聚糖与饼干直径亦呈极显著负相关;与吹泡示功仪参数、RVA参数也具有较为丰富的相关性.本研究进一步证实宁麦9号和扬麦13具有良好的饼干品质.密穗小麦具有较低的戊聚糖含量,同时其饼干直径、厚度、直径/厚度均与弱筋小麦品种相近,可能是一个优良的弱筋、低戊聚糖含量的饼干小麦资源.     

Vegetation and weather explain variation in crown damage within a large mixed-severity wildfire

The 2002 Biscuit Fire burned through more than 200,000 ha of mixed-conifer/evergreen hardwood forests in southwestern Oregon and northwestern California. The size of the fire and the diversity of conditions through which it burned provided an opportunity to analyze relationships between crown damage and vegetation type, recent fire history, geology, topography, and regional weather conditions on the day of burning. We measured pre- and post-fire vegetation cover and crown damage on 761 digital aerial photo-plots (6.25 ha) within the unmanaged portion of the burn and used random forest and regression tree models to relate patterns of damage to a suite of 20 predictor variables. Ninety-eight percent of plots experienced some level of crown damage, but only 10% experienced complete crown damage. The median level of total crown damage was 74%; median damage to conifer crowns was 52%. The most important predictors of total crown damage were the percentage of pre-fire shrub-stratum vegetation cover and average daily temperature. The most important predictors of conifer damage were average daily temperature and “burn period,” an index of fire weather and fire suppression effort. The median level of damage was 32% within large conifer cover and 62% within small conifer cover. Open tree canopies with high levels of shrub-stratum cover were associated with the highest levels of tree crown damage, while closed canopy forests with high levels of large conifer cover were associated with the lowest levels of tree crown damage. Patterns of damage were similar within the area that burned previously in the 1987 Silver Fire and edaphically similar areas without a recent history of fire. Low-productivity sites on ultramafic soils had 92% median crown damage compared to 59% on non-ultramafic sites; the proportion of conifer cover damaged was also higher on ultramafic sites. We conclude that weather and vegetation conditions — not topography — were the primary determinants of Biscuit Fire crown damage.     

Bird communities following high-severity fire: Response to single and repeat fires in a mixed-evergreen forest,Oregon, USA

Fire is a widespread natural disturbance agent in most conifer-dominated forests. In light of climate change and the effects of fire exclusion, single and repeated high-severity (stand-replacement) fires have become prominent land management issues. We studied bird communities using point counting in the Klamath-Siskiyou ecoregion of Oregon, USA at various points in time after one or two high-severity fires. Time points included 2 and 3 years after a single fire, 17 and 18 years after a single fire, 2 and 3 years after a repeat fire (15 year interval between fires), and >100 years since stand-replacement fire (mature/old-growth forest). Avian species richness did not differ significantly among habitats. Bird density was highest 17 and 18 years after fire, lowest 2 years after fire, and intermediate in repeat burns and unburned forest. Bird community composition varied significantly with habitat type (A = 0.24, P < 0.0001) with two distinct gradients in species composition relating to tree structure (live to dead) and shrub stature. Using indicator species analysis, repeat burns were characterized by shrub-nesting and ground-foraging bird species while unburned mature forests were characterized by conifer-nesting and foliage-gleaning species. Bird density was not related to snag basal area but was positively related to shrub height. Contrary to expectations, repeated high-severity fire did not reduce species richness, and bird densities were greater in repeat burns than in once-burned habitats. Broad-leaved hardwoods and shrubs appear to play a major role in structuring avian communities in the Klamath-Siskiyou region. In light of these results, extended periods of early seral broadleaf dominance and short-interval high-severity fires may be important to the conservation of avian biodiversity.     

无糖发酵功能饼干加工技术的研究

以面粉为主要原料,添加燕麦粉、麦芽糖醇和松化酶制作无糖发酵功能饼干。通过单因素试验和正交试验确定了无糖发酵功能饼干的最优工艺参数。结果表明:制作无糖发酵功能饼干的最佳工艺条件为:燕麦15%,麦芽糖醇10%,发酵3.5h,夹酥6次。     

Effect of wheat bran addition on in vitro starch digestibility,physico-mechanical and sensory properties of biscuits

Biscuits contain high amount of fat and sugar thus having high calorie but low nutrient density. Wheat bran is a good source of dietary fibre (DF) and protein and is thus a good candidate for nutritional enrichment of cereal foods. The aim of this study was to understand the effect of bran incorporation and particle size reduction on biscuit microstructure, texture and in vitro starch digestibility. Five different biscuits containing 5–15% DF were produced. Two different particle sized wheat brans were used: coarse (450 μm) and fine (68 μm). Bran particle size reduction increased the elastic modulus and hardness of biscuits. Biscuits containing fine bran had visually more compact structure without any surface or internal defects than those with coarse bran. Fine bran containing sample had the highest hardness value. Sensory evaluation showed that roughness and breakdown of biscuits in the mouth was significant for the coarse bran with highest level of bran addition. The instrumental elastic modulus, stress and hardness were closely related to sensory hardness and strength to break. Increasing DF content from 5 to 15% increased hydrolysis index by 16%, from 32 to 37.     

Variation in rheological properties of gluten from three biscuit wheat cultivars in relation to nitrogen fertilisation

Rheological properties of gluten from three biscuit wheat cultivars (Triticum aestivum, L., cv. Reaper, Ritmo, Encore) were studied. The cultivars were grown in two seasons (1997–1999) with three different nitrogen levels, and nitrogen fertiliser was applied using three different strategies. Protein and gluten contents were significantly affected by the N level (P<0.001), but inter-cultivar differences were only significant in 1999, when growing conditions were restricted by environmental factors. The viscoelastic properties of gluten were characterised by creep recovery and oscillation testing. The results showed a significant inter-cultivar effect (P<0.001), with an additional effect from the N level (P<0.001). Increasing levels of nitrogen fertiliser increased the viscous properties of gluten, through an increase of maximum strain and recovery strain, and through a decrease of the storage (G′) and loss modulus (G′′), whereas the phase angle, δ, increased. This increase in viscous behaviour is suggested to be attributed to a higher gliadin/glutenin ratio in the gluten. The fertiliser application strategy did not influence the rheological properties significantly. Thus, high N fertiliser application in biscuit wheat cultivation may be beneficial to obtain rheological properties, which are suitable for biscuit making.