提取玉米皮膳食纤维的条件优化

通过单因素试验和正交试验,探讨了加酶量、酶解温度、酶解时间和酶解pH值对玉米皮膳食纤维提取率的影响效果.结果表明,提取玉米皮膳食纤维的最佳条件为复合酶添加量1.2%,酶解温度60 ℃,酶解55 min,pH7.0,提取率可达65.2%.玉米皮膳食纤维优质化挤压条件为物料加水量20%,挤压温度130 ℃,螺杆转速130 r/min,玉米皮中的水溶性膳食纤维含量可由15.87%提高到21.65%.     

Effects of Particle Size and Processing Variables on the Properties of an Extruded Catfish Feed

Abstract

A catfish feed was extruded to determine how particle size, moisture content and screw speed affected the pellet durability, water stability index, and buoyancy. Increasing moisture content from 250 to 300 g/kg required less die pressure, specific mechanical energy and product temperature to produce durable pellets that were stable in water. Increasing screw speed from 200 to 400 rpm also lowered die pressure, due to a lower filled length of the extruder screw channels, but increased specific mechanical energy and product temperature; the resulting pellets had a lower apparent bulk density, but a higher degree of starch gelatinization and water stability index. Reducing particle size from 1200 to 700 m decreased die pressure and apparent bulk density, but increased product temperature, degree of starch gelatinization, pellet durability index and water stability index.     

Modeling the Inclusion of Fish Powder and Fish Oil into Extruded Snacks by Response Surface Methodology

ABSTRACT

Extrusion cooking plays an important role in the production of puffed snacks, which enjoy wide acceptance all over the world and are potential vehicles for increasing the consumption of n-3 fatty acids. Response surface methodology (RSM) with central composite design was adopted to investigate the effects of four independent variables (fish powder, fish oil, moisture, and screw speed) at five levels on expansion ratio, breaking strength index, hardness, color, and thiobarbituric acid reactive substances (TBARS). A second order polynomial model was used to study the main, interactive, and quadratic effects of the independent variables and to explain the relationship between the responses and independent variables. Moisture was found to be the most significant factor (p < 0.001) influencing expansion ratio, breaking strength index, and color. Inclusion of fish powder and fish oil were found to be negatively associated with the expansion characteristics, resulting in decreased lipid oxidation due to less exposed surface area of the extrudates to air. Further, the absence of linear effect of fish powder and fish oil on TBARS demonstrated the possibility to incorporate higher levels of these ingredients to produce oxidatively stable extruded snacks rich in fish proteins.     

中国鲜面条耐煮特性及评价指标

以我国北部和黄淮冬麦区的46份主栽小麦品种和育成品系为材料, 分析了品质性状与煮熟面条冲洗水中总有机物含量(TOM)、干物质蒸煮损失率、面条吸水性和黏性等面条耐煮性指标的关系。结果表明, 小麦品种的磨粉品质、面团流变学特性、淀粉品质及TOM值、蒸煮损失率和黏性等面条耐煮性指标存在较大变异。拉伸面积和最大抗延阻力与TOM值呈显著负相关, 相关系数分别为-0.66 (P<0.01)和-0.56 (P <0.01); 稳定时间、拉伸面积和最大抗延阻力与面条煮6 min和10 min后鲜重的相关系数为-0.55~ -0.63 (P <0.01), 耐揉指数与二者的相关系数分别为0.67 (P<0.01)和0.69 (P<0.01); 糊化温度与面条煮10 min后鲜重呈极显著正相关(r = 0.60, P<0.01), 说明提高小麦面粉的蛋白质含量、面筋强度可以显著改善面条耐煮特性, 蛋白质特性是影响面条耐煮性的主要品质因子, 淀粉糊化参数对面条耐煮性也有一定影响。TOM值与面条煮6 min和10 min后鲜重呈显著正相关, 相关系数分别为0.66 (P<0.01)和0.69 (P<0.01); 面条煮6 min与煮10 min后鲜重也呈高度正相关(r = 0.86, P<0.01)。建议将10 g鲜面条煮10 min后的鲜重≤21.0 g作为优质鲜面条耐煮性的主要评价指标。     

An assessment of cereal grains and other starch sources in diets for barramundi (Lates calcarifer) – implications for nutritional and functional qualities of extruded feeds

This study examined the digestibilities of whole diets and ingredients of a range of starch/cereal grains when fed to barramundi (Lates calcarifer). The ingredients included wheat, oats, sorghum, triticale, barley, among others. Twelve diets were prepared using a twin‐screw extruder to mimic modern aquafeed‐manufacturing processes. The diets were then fed to juvenile barramundi and the faeces collected using stripping methods. Significant variability in the digestible energy and starch value was seen among the test ingredients and diets. Diet starch digestibility ranged from 49.1% to 93.9%. Ingredient starch digestibility ranged from 18.0% to 96.5%. Among the different starch ingredients, a strong negative correlation between the ingredient amylopectin content and starch digestibility of that ingredient was observed. This relationship was also mirrored by a similar relationship, although not as strong, between total starch and starch digestibility. This study demonstrates that barramundi have limited ability to digest starch and that there is an effect of inclusion level on the ability of the animal to digest this nutrient. But it also demonstrates that there is a wide range of cereal sources that can be effectively used as starch sources in extruded diets for this species.     

Evaluation of T2‐weighted versus short‐tau inversion recovery sagittal sequences in the identification and localization of canine intervertebral disc extrusion with low‐field magnetic resonance imaging

Sagittal T2‐weighted sequences (T2‐SAG) are the foundation of spinal protocols when screening for the presence of intervertebral disc extrusion. We often utilize sagittal short‐tau inversion recovery sequences (STIR‐SAG) as an adjunctive screening series, and experience suggests that this combined approach provides superior detection rates. We hypothesized that STIR‐SAG would provide higher sensitivity than T2‐SAG in the identification and localization of intervertebral disc extrusion. We further hypothesized that the parallel evaluation of paired T2‐SAG and STIR‐SAG series would provide a higher sensitivity than could be achieved with either independent sagittal series when viewed in isolation. This retrospective diagnostic accuracy study blindly reviewed T2‐SAG and STIR‐SAG sequences from dogs (n = 110) with surgically confirmed intervertebral disc extrusion. A consensus between two radiologists found no significant difference in sensitivity between T2‐SAG and STIR‐SAG during the identification of intervertebral disc extrusion (T2‐SAG: 92.7%, STIR‐SAG: 94.5%, P = 0.752). Nevertheless, STIR‐SAG accurately identified intervertebral disc extrusion in 66.7% of cases where the evaluation of T2‐SAG in isolation had provided a false negative diagnosis. Additionally, one radiologist found that the parallel evaluation of paired T2‐SAG and STIR‐SAG series provided a significantly higher sensitivity than T2‐SAG in isolation, during the identification of intervertebral disc extrusion (T2‐SAG: 78.2%, paired T2‐SAG, and STIR‐SAG: 90.9%, P = 0.017). A similar nonsignificant trend was observed when the consensus of both radiologists was taken into consideration (T2‐SAG: 92.7%, paired T2‐SAG, and STIR‐SAG = 97.3%, P = 0.392). We therefore conclude that STIR‐SAG is capable of identifying intervertebral disc extrusion that is inconspicuous in T2‐SAG, and that STIR‐SAG should be considered a useful adjunctive sequence during preliminary sagittal screening for intervertebral disc extrusion in low‐field magnetic resonance.     

Raw mechanically separated chicken meat and salmon protein hydrolysate as protein sources in extruded dog food: effect on protein and amino acid digestibility

Protein quality was evaluated for mechanically separated chicken meat (MSC) and salmon protein hydrolysate (SPH), and for extruded dog foods where MSC or SPH partially replaced poultry meal (PM). Apparent total tract digestibility (ATTD) of crude protein (CP) and amino acids (AA) in the protein ingredients and extruded foods was determined with mink (Neovison vison). The extruded dog foods included a control diet with protein from PM and grain, and two diets where MSC or SPH provided 25% of the dietary CP. Nutrient composition of the protein ingredients varied, dry matter (DM) was 944.0, 358.0 and 597.4 g/kg, CP was 670.7, 421.2 and 868.9 g/kg DM, crude fat was 141.4, 547.8 and 18.5 g/kg DM and ash was 126.4, 32.1 and 107.0 g/kg DM for PM, MSC and SPH respectively. The content of essential AA (g/100 g CP) was more than 10.0 percentage units lower in SPH than in PM and MSC. The ATTD of CP differed (p < 0.001) between protein ingredients and was 80.9%, 88.2% and 91.3% for PM, MSC and SPH respectively. The ATTD of total AA was lowest (p < 0.001) for PM, and similar (p > 0.05) for MSC and SPH. In the extruded diets, the expected higher ATTD of CP and AA from replacement of PM with MSC or SPH was not observed. The ATTD of CP was determined to be 80.3%, 81.3% and 79.0% for the PM, MSC and SPH extruded foods respectively. Furthermore, the ATTD of several AA was numerically highest for the PM diet. Possibly, extrusion affected ATTD of the diets differently due to different properties and previous processing of the three protein ingredients.     

对辊挤压式对虾去头装置试验研究

针对人工去虾头工作效率低、劳动强度大、虾仁易受细菌污染和机械一刀切式对虾去头方法对虾肉浪费严重等问题,设计了一种对辊挤压式对虾去头装置。该装置根据对虾的生物特性和体型特征,利用对辊之间的间隙和对辊表面上沿圆周方向设置的凸棱对虾头进行挤压使得对虾在头胸部与虾体连接处被挤断,从而实现对虾的头尾分离工作,并进行了原理分析。针对按对虾厚度分级后体厚为13~16mm的新鲜南美白对虾进行了试验研究,结果表明利用对辊挤虾头式去虾头的方法去头效果良好,去头装置原理合理,为今后对虾去头装置的研制提供了新的思路和依据。     

烹调方式对菠菜、芥蓝中维生素C、维生素K_1和类胡萝卜素的影响

采用化学测定方法对汽蒸和水焯处理不同时间的菠菜和芥蓝中的维生素C、维生素K1和α-胡萝卜素、β-胡萝卜素和叶黄素含量进行研究。结果表明:1)维生素K1和叶黄素的烹调损失低于10%;2)维生素C在水焯处理后损失较大,在菠菜和芥蓝中的保存率分别为41.6%和61.7%;3)各营养素保存率均以汽蒸烹调更佳。短时汽蒸烹调处理时,无论脂溶性还是水溶性营养素保存率均较高,适宜作为绿叶蔬菜的少油烹调方法。     

食品挤压技术装备及工艺机理研究进展

以营养、低能耗、快捷为特点的新型食品挤压技术如超临界流体挤压(supercritical fluid extrusion)、双阶或多级挤压、挤压机与3D打印机等设备联用、智能化控制模拟技术受到关注。该文梳理了食品挤压技术装备发展概况;比较了普通低水分和高水分挤压、超临界CO2挤压、双阶或多级挤压以及挤压-3D打印联用等工艺技术的特点;总结了食品挤压能量输入与蛋白构象变化关系机理。结果认为:1)通过改进挤压设备材料和结构及与中近红外设备、流变仪、拉曼光谱仪等设备联用,提高其通用性、可视性和智能性,实现挤压过程全程监控,是今后挤压设备研发的方向。2)控制挤压过程中能量输入方式或大小,是挤压工艺研究要解决的主要问题,也是挤压工艺放大生产的关键点。3)建立挤压能量输入方式或大小、物料组分结构变化及产品品质形成研究体系,研究结果为实现挤压过程中能量输入精准调控提供参考。