Modulation of starch digestibility using non-thermal processing techniques:A review

Obesity and type 2 diabetes are widespread throughout the world, especially in developed countries. Starch is an important part of human staple food, the modulating of starch digestibility is conducive to reducing postprandial blood glucose levels and alleviating the chronic disease caused by high caloric intake. The digestion properties of starch are correlated with its structural features, including crystallization, amylose/amylopectin ratio, non-starch components, etc. Among the modified methods applied to regulate starch digestibility, non-thermal processing techniques(NTPT) receive extensive attention due to the characteristics of safety, environmental friendliness and high efficiency. The influence and mechanism of NTPT on the digestion properties of starch are discussed in this review, including ultrasounds, high pressure, γ-irradiation, etc. NTPT induces the alternation of morphological and structural characteristics of native starch, changing their sensitivity to enzymes. The effects of NTPT on the digestibility of starch are highly related to the processing parameters and structure characteristics of native starch. The review shows that NTPT is an effective way to modulate the digestion properties of starch and prevent people from suffering from chronic diseases such as obesity and type 2 diabetes.

Multi-objective optimization based optimal setting control for industrial double-stream alumina digestion process

The operation variables,including feed rate of ore slurry,caustic solution and live steams in the double-stream alumina digestion process,determine the product quality,process costs and the environment pollution.Previously,they were set by the technical workers according to the offline analysis results and an empirical formula,which leads to unstable process indices and high consumption frequently.So,a multi-objective optimization model is built to maintain the balance between resource consumptions and process indices by taking technical indices and energy efficiency as objectives,where the key technical indices are predicted based on the digestion kinetics of diaspore.A multi-objective state transition algorithm(MOSTA)is improved to solve the problem,in which a self-adaptive strategy is applied to dynamically adjust the operator factors of the MOSTA and dynamic infeasible threshold is used to handle constraints to enhance searching efficiency and ability of the algorithm.Then a rule based strategy is designed to make the final decision from the Pareto frontiers.The method is integrated into an optimal control system for the industrial digestion process and tested in the actual production.Results show that the proposed method can achieve the technical target while reducing the energy consumption.

Conversion of ferric oxide to magnetite by hydrothermal reduction in Bayer digestion process

Digesting aluminum-bearing minerals and converting ferric oxide to magnetite simultaneously in Bayer digestion process is crucially important to deal with high-iron diasporic bauxite economically for alumina production.The reaction behaviors of hydrothermal reduction of ferric oxide in alkali solution were studied by both thermodynamic calculation and experimental investigation.The thermodynamic calculation indicates that Fe3O4 can be formed by the conversion of Fe2O3 at proper redox potentials in alkaline solution.The experimental results show that the formation ratio of Fe3O4 either through the reaction of Fe and Fe2O3 or through the reaction of Fe and H2O in alkaline aqueous solution increases remarkably with raising the temperature and alkali concentration,suggesting that Fe（OH）3- and Fe（OH）4- form by dissolving Fe and Fe2O3,respectively,in alkaline aqueous solution and further react to form Fe3O4.Moreover,aluminate ions have little influence on the hydrothermal reduction of Fe2O3 in alkaline aqueous solution,and converting iron minerals to magnetite can be realized in the Bayer digestion process of diasporic bauxite.

Characteristics of high-sulfate wastewater treatment by two-phase anaerobic digestion process with Jet-loop anaerobic fluidized bed

A new anaerobic reactor, Jet-loop anaerobic fluidized bed （JLAFB）, was designed for treating high-sulfate wastewater. The treatment characteristics, including the effect of influent COD/SO42 ratio and alkalinity and sulfide inhibition in reactors, were discussed for a JLAFB and a general anaerobic fiuidized bed （AFB） reactor used as sulfate-reducing phase and methane-producing phase, respectively, in two-phase anaerobic digestion process. The formation of granules in the two reactors was also examined. The results indicated that COD and sulfate removal had different demand of influent COD/SO4^2- ratios. When total COD removal was up to 85%, the ratio was only required up to 1.2, whereas, total sulfate removal up to 95% required it exceeding 3.0. The alkalinity in the two reactors increased linearly with the growth of influent alkalinity. Moreover, the change of influent alkalinity had no significant effect on pH and volatile fatty acids （VFA） in the two reactors. Influent alkalinity kept at 400-500 mg/L could meet the requirement of the treating process. The JLAFB reactor had great advantage in avoiding sulfide and free-H2S accumulation and toxicity inhibition on microorganisms. When sulfate loading rate was up to 8. 1 kg/（m^3.d）, the sulfide and free-H2S concentrations in JLAFB reactor were 58.6 and 49.7 mg/L, respectively. Furthermore, the granules, with offwhite color, ellipse shape and diameters of 1.0-3.0 mm, could be developed in JLAFB reactor. In granules, different groups of bacteria were distributed in different layers, and some inorganic metal compounds such as Fe, Ca, Mg etc. were found.

CONTROL TECHNIQUES FOR DIGESTION IN BAYER PROCESS

The control techniques for indirect heating digestion in Bayer process of alumina production were researched and developed. They include controlling chemical composition of slurry to be digested and controlling digestion status and energy consumption. Very good performances and technical and technical and economical figures for digestion process have been obtained by carefully applying these comprehensive control techniques in Pingguo alumina refinery.

Co-digestion of Waste Coffee and Cocoa Hulls: Modeling of Biogas Production by the Particle Swarm Method

Energy is a crucial material for the development of our economy.Access to sufficient energy remains a major concern for developing countries,particularly those in sub-Saharan Africa.The major challenge lies in access to clean,environmentally friendly,quality and low-cost energy in different households in our municipalities.To cope with this vast energy gap,many households are dependent on fossil fuels.In Cameroon,the consumption of wood for the supply of energy is increasing by 4%per year.Overall,approximately 80%of households in Cameroon depend on woody biomass as the sole main source of energy supply in Cameroon and demand is growing over time.In view of the climatic variations that our countries,particularly Cameroon,undergo through deforestation,the use of wood as a source of energy is expensive and harmful to the environment,hence the urgency of replacing wood with renewable energy.Biogas is one of the most versatile sources of renewable energy.On an industrial scale,it is important to automate the process control.The main objective of the present work is to model the anaerobic digestion of coffee and cocoa hulls using the particle swarm optimisation method.Pretreatment using the organosolv process was done.This resulted in 48%lignin removal and 22%cellulose increase.For the pretreated biomass,the maximum production rate was 21 NmLCH4 per day with a biomethane yield of 90 NmLCH4/gVS.This represents an enhancement of 117%in biomethane yield.A positive flammability test was recorded after the 10th day of retention time.Moreover,the data collected during anaerobic digestion allowed implementation of a two-phase mathematical model.The thirteen parameters of the model were estimated with particle swarm optimisation method in Matlab.The model was able to simulate the biomethane production kinetics and variation of volatile fatty acid concentration.

Alkaline digestion behavior and alumina extraction from sodium aluminosilicate generated in pyrometallurgical process

In pyrometallurgical process, Al-and Si-bearing minerals in iron and aluminum ores are easily transformed into sodium aluminosilicates in the presence of Na_2O constituents, which alters the leaching behaviors of Al_2O_3 and SiO_2. It was confirmed that sodium aluminosilicates with different phase compositions synthesized at various roasting conditions were effectively digested in the alkaline digestion process. Under the optimum conditions at temperature of 100–120°C, liquid-to-solid ratio(L/S) of 10:2 mL/g, caustic ratio of 4, and Na_2O concentration of 240 g/L, the actual and relative digestion ratio of Al_2O_3 from the synthesized sodium aluminosilicates reached maximums of about 65% and 95%, respectively, while SiO_2 was barely leached out. To validate the superior digestion property of sodium aluminosilicate generated via an actual process, the Bayer digestion of an Al_2O_3-rich material derived from reductive roasting of bauxite and comprising Na_(1.75) Al_(1.75) Si_(0.25)O_4 was conducted; the relative digestion ratio of Al_2O_3 attained 90% at 200°C.

Influence of temperature on performance of anaerobic digestion of municipal solid waste

The influence of temperature on the performance of anaerobic reactors for treating the organic fraction of municipal sohd waste （OFMSW） was studied. Batch digestion of OFMSW was carded out for 32 d at different temperature （25℃, 35℃, 45℃ and 55℃） conditions for total solid concentrations （TS） 17% with the ratio of total organic carbon to nitrogen （C/N） being, 25：1 respectively, while keeping other parameters constant such as inoculum, start-up pH, reactor volume （2 L） and so on. Temperature can influence the methanogenic bacteria activity, accordingly inhibiting the OFMSW biodegradation and stabilization efficiency. Anaerobic reactors excelled at TS reduction, total volatile solid reduction, chemical oxygen demand reduction, increasing cumulative biogas production, whose rate was at temperature （35℃ and 55℃） conditions. Methane concentration in the biogas was above 65% in four reactors. In addition, the fluctuation of temperatures resulted in the biogas production variation. The data obtained indicated that temperature had a significant influence on anaerobic process.

Facultative-anaerobic microbial digestion of coal preparation waste and use of effluent solids to enhance plant growth in a sandy soil

Coal preparation solid waste,which is a major environmental issue for coal-producing areas in China,may be microbiologically digested and transformed into a product suitable as a soil amendment to increase soil organic matter content and prevent and enhance plant/crop growth.Coal preparation waste collected from a coal sorting plant in Inner Mongolia,China was digested in bioreactors inoculated with microbial enrichments prepared from activated sludge and cow manure.The effluent solids from the coal preparation waste bioreactors were analyzed for their suitability as organic soil amendments,which complied with China standards.Plant growth tests were conducted in sandy soil from a semi-arid region in Colorado,which was amended with the effluent solids.Kentucky bluegrass(Poa pratensis L.)and chives(Allium schoenoprasum)were used as the representative plants for the growth tests,where results indicated substantially higher yields of Kentucky bluegrass and chives for the sandy soils amended with the effluent solids when compared to a commercial organic fertilizer.The number and average length of Kentucky bluegrass shoots were 10 and 5.1 times higher,respectively,in soils amended with the effluent solids.Similarly,the number and average length of chives shoots were 10 and 1.7 times higher,respectively,in soils amended with the effluent solids.Overall,the microbial digestion of coal preparation waste for application as an organic soil amendment is a viable alternative and beneficial use of coal preparation solid waste.

Stability and Uniform Boundedness for a Class of Anaerobic Digestion Ecological Models

Stability, boundedness and persistence are three important aspects for an ecological model. In this paper, a further analysis of a class of anaerobic digestion ecological models is performed. Based on the Liupunov Method, the local stability of all equilibria in the system is got. According to the vector fields described by the system, the proof of the boundedness of the solution on the anaerobic digestion processes is completed in three steps. The method proposed in the discussion on the boundedness can be generalized to the similar problems. Results in this paper give information on how to run the ecological system well by adjusting the system parameters.

生长抑素在肿瘤合并肠梗阻姑息治疗中的应用

目的观察静脉持续泵入生长抑素在肿瘤合并肠梗阻姑息治疗中的应用效果。方法选取85例肿瘤合并肠梗阻患者为研究对象,随机分为两组。常规组42例予以胃肠减压治疗,试验组43例采用生长抑素辅助治疗。比较两组患者的胃肠动力、胃消化功能、炎症因子、免疫功能变化情况及恢复情况。结果在不同治疗方案下,试验组胃泌素(GAS)、胃动素(MLT)的水平均高于常规组,差异有统计学意义(P<0.05);试验组胃蛋白酶Ⅰ(PGⅠ)、胃蛋白酶Ⅱ(PGⅡ)的水平均高于常规组(P<0.05);试验组C-反应蛋白(CRP)、降钙素原(PCT)、白细胞介素-6(IL-6)的水平均低于常规组(P<0.05);试验组的T淋巴细胞CD3^(+)、CD4^(+)、CD4^(+)/CD8^(+)的水平均高于常规组(P<0.05);试验组的恢复自主进食时间、首次排气时间、首次排便时间、腹部不适缓解时间、住院时间均短于常规组(P<0.05)。结论经静脉持续泵入生长抑素能改善肿瘤合并肠梗阻患者的胃肠动力及胃消化功能,对缓解患者炎症反应、增强机体免疫力、加快康复进程均有积极意义。

湿法膨化和发酵豆粕对断奶仔猪生长性能、免疫功能及氨基酸消化率的影响

[目的]本试验旨在探究湿法膨化和发酵豆粕对断奶仔猪生长性能、免疫功能及氨基酸消化率的影响。[方法]选用21日龄、体重相近,公母各半的288头断奶仔猪,随机分为4组,每组6个重复,每个重复12头。常规组(Con)饲喂常规豆粕,3个试验组分别为湿法膨化1组(WeSM1)、湿法膨化2组(WeSM2)和发酵组(FSM),分别饲喂湿法膨化豆粕和发酵豆粕。在试验的14和49 d,于每个重复中随机选取1只健康状况良好的断奶仔猪采血。在试验的47~49 d,连续收集3 d的粪便用于养分及氨基酸消化率的测定。[结果]湿法膨化1组和湿法膨化2组断奶仔猪平均日增重和采食量均高于常规组(P>0.05),以湿法膨化1组的效果最优。发酵组料重比显著高于常规组(P<0.05)。与常规豆粕和发酵豆粕相比,饲喂湿法膨化豆粕可以显著提高断奶仔猪总能、粗灰分的表观消化率(P<0.05);与常规组相比,其他3组赖氨酸、精氨酸、丝氨酸和天冬氨酸表观消化率显著提高(P<0.05),以湿法膨化1组效果最好。与常规组相比,湿法膨化2组和发酵组仔猪血清游离精氨酸、赖氨酸、酪氨酸含量显著提高(P<0.05)。在试验14 d,与常规组相比,发酵组血清球蛋白含量显著提高,白蛋白与球蛋白之比显著降低(P<0.05),发酵组和湿法膨化2组断奶仔猪血清中IgM含量显著提高(P<0.05),湿法膨化1组和2组及发酵组仔猪血清中MDA的含量均显著降低(P<0.05);与湿法膨化1组、湿法膨化2组相比,发酵组试验49 d血清中GSH-Px的活性显著提高(P<0.05)。[结论]豆粕经湿法膨化和发酵处理能够提高断奶仔猪的生长性能、养分消化率、血清抗氧化和免疫相关指标及游离氨基酸含量,且发酵豆粕在提高血清抗氧化及免疫功能方面优于湿法膨化豆粕,但在提高仔猪生长性能、养分表观消化率方面不及湿法膨化豆粕。

新型辅助加工技术提高肉制品消化特性的研究进展

随着国民生活质量的提高,人们对肉制品的需求也不再仅仅局限于感官质量和卫生质量等基本特性。肉制品中蛋白质含量高达10%~20%,是人体不可缺少的营养物质。近年来,如何提高肉制品的消化率这一问题受到了广泛的关注。目前,改善肉制品中蛋白质的结构和功能特性是提高消化率的主要可行性途径。在传统蒸煮、烘烤等加工方式的前提下,肉制品的制作过程中辅以新型加工技术(如超声波、超高压、脉冲电场、真空低温烹饪、酶解技术等),可以达到改变蛋白质结构、提高蛋白水解酶活性的目的,从而提高肉制品的消化率。本文系统综述新型辅助加工技术在提高肉制品消化特性方面的研究进展,旨在探求更经济有效的加工方法,为提高肉制品的消化特性提供理论基础。

双酶协同增加青稞慢消化淀粉含量的工艺优化

以萌芽黑青稞粉为原料,研究β-淀粉酶协同α-葡萄糖苷酶增加青稞慢消化淀粉含量及其体外降糖活性。通过单因素试验、体外模拟消化法和Box-Behnken响应面试验,确定最优工艺条件,并通过α-淀粉酶和α-葡糖苷酶抑制率的测定,评价其体外降糖活性。结果表明,双酶协同增加青稞慢消化淀粉含量的酶解最优条件为β-淀粉酶、α-葡萄糖苷酶添加量150 U/g青稞粉、酶解时间8 h、酶解温度50℃、青稞粉浓度10%。此条件下青稞慢消化淀粉含量达到最高,为33.62%。体外降糖活性测定结果显示,与原粉相比酶改性青稞粉的α-淀粉酶抑制率增加了62.97%,α-葡萄糖苷酶的抑制率增加了52.46%,表明酶解粉的体外降糖活性明显提高。

酶解法制备花生肽及其抗氧化活性分析

为提高花生粕利用价值,开发健康安全的花生肽功能食品,采用碱提酸沉法提取花生蛋白,利用碱性蛋白酶酶解制备花生抗氧化肽,通过单因素试验、 Plackett-Burman试验和响应面试验优化花生抗氧化肽的制备工艺,并对其酶解前后的成分和结构进行测定,通过体外模拟胃肠道消化评价其抗氧化稳定性。结果表明:酶解花生蛋白制备花生抗氧化肽的最佳工艺条件为酶解pH9.5、温度50℃、碱性蛋白酶添加量6 100 U/g、底物浓度4%、时间4 h,在此条件下制备的花生抗氧化肽ABTS自由基清除率可达90.31%±0.53%、水解度可达35.06%±1.29%,与预测值无显著性差异;采用此工艺制备的花生肽抗氧化活性较花生蛋白提升约50%;体外模拟消化后,花生肽仍保持了较高的抗氧化活性。研究结果为花生抗氧化肽的高效制备及推动花生粕在食品加工行业的应用提供了理论依据。

结合态酚类物质在植物生长、食品加工及人体消化过程中的释放规律研究进展

酚类物质具有抗氧化、抗炎、改善机体肠道健康等多种生理作用,在植物体生长及调节人体健康方面有着重要作用。相较于可直接萃取的游离态酚类物质,与多糖、蛋白质、脂质等结合的结合态酚类物质,所占比例更高,分布更广,具有潜在的应用价值,受到了越来越多的关注。结合态酚类物质从植物生长到食品加工再到人体消化利用全链条过程中,因受到多种因素影响,其组成、结构、迁移转化、赋存特征等会发生复杂的变化,研究其积累与释放规律对增强其生物活性,提高酚类利用率尤为重要。因此,本文就结合态酚类物质在植物生长、食品加工及人体消化过程中的释放研究情况进行简要综述,以期为阐明结合态酚类释放规律及提高其利用率提供理论指导。

“葵花壳+玉米秸秆”加工粉尘对合作猪养分消化率、小肠组织形态和消化酶活性的影响

试验旨在研究饲粮中添加“葵花壳+玉米秸秆”加工粉尘对合作猪养分消化率、小肠组织形态和消化酶活性的影响。选择平均体重为(9.88±0.82)kg的合作猪50头,进行7 d预试验,饲喂基础饲粮。预试验结束后选取40头平均体重为(11.94±1.43)kg的合作猪,随机分为4组,每组10个重复,每个重复1头猪。对照组饲喂基础饲粮,试验Ⅰ、Ⅱ、Ⅲ组分别饲喂添加5%、10%和15%的“30%葵花壳+70%玉米秸秆”加工粉尘的基础饲粮,正式试验期90 d。结果表明:①试验Ⅱ组粗蛋白和酸性洗涤纤维消化率显著高于对照组(P<0.05);试验Ⅱ、Ⅲ组中性洗涤纤维消化率均显著高于对照组(P<0.05)。②试验Ⅱ组十二指肠绒毛高度显著高于对照组(P<0.05),试验Ⅱ、Ⅲ组空肠绒毛高度显著高于对照组(P<0.05);试验Ⅰ、Ⅱ、Ⅲ组十二指肠隐窝深度极显著低于对照组(P<0.01);试验Ⅰ、Ⅲ组十二指肠绒隐比显著高于对照组(P<0.05),试验Ⅱ组十二指肠绒隐比极显著高于对照组(P<0.01);空肠隐窝深度和绒隐比差异不显著(P>0.05)。③试验Ⅱ、Ⅲ组十二指肠内蛋白酶活性极显著高于对照组(P<0.01),试验Ⅱ组空肠内蛋白酶活性显著高于对照组(P<0.05);试验Ⅱ组试验猪十二指肠内淀粉酶活性显著高于对照组(P<0.05),试验Ⅰ、Ⅱ、Ⅲ组空肠内淀粉酶活性极显著高于对照组(P<0.01)。综上可知,饲粮中添加“葵花壳+玉米秸秆”加工粉尘,可提高合作猪的养分消化率、十二指肠和空肠内蛋白酶和淀粉酶活性,能够改善小肠组织形态,添加水平以10%最佳。

蒸制对甘薯可溶性膳食纤维提取、理化性质及消化特性的影响

目的:考察蒸制前、后甘薯中可溶性膳食纤维(SDF)提取、组成及性质的差异。方法:为获得高品质甘薯SDF,以提高提取得率和SDF总多糖含量为目标,采用响应面分析和满意度函数方法优化料液比、提取温度、提取时间3个参数,建立甘薯SDF提取工艺。从蒸制前、后的甘薯中提取得到生鲜甘薯膳食纤维(SDF-F)和蒸制甘薯膳食纤维(SDF-S),对比两者提取得率、多糖组成、膳食纤维含量以及持水力和持油力等理化性质差异,并做体外模拟消化试验。结果:优化的提取工艺参数为:料液比1∶16、提取温度40℃、提取时间40 min。在此工艺条件下,SDF-S的提取得率【(6.13±0.25)%vs(2.89±0.18)%】、中性多糖含量【(59.31±0.73)%vs(46.83±0.63)%】、酸性多糖含量【(25.36±0.48)%vs(9.60±0.14)%】、膳食纤维含量【(54.71±6.70)%vs(35.69±3.25)%】、持水力【(4.60±0.31)g/g vs(3.27±0.21)g/g)】和持油力【(3.30±0.40)g/g vs(1.82±0.28)g/g)】显著高于SDF-F(P<0.05),而SDF-F的抗消化性优于SDF-S。结论:蒸制处理虽提高了甘薯SDF的可及性,但导致SDF的抗消化性减弱。

马铃薯鲜湿面的制备及其品质评价

目的探究不同原料配方对面团混合特性和马铃薯鲜湿面条蒸煮、质构特性的影响,并对鲜湿面配方进行优化。方法在单因素试验中研究马铃薯全粉、芦笋全粉、水、谷朊粉、魔芋胶添加量对面团混合特性以及鲜湿面的蒸煮特性和质构特性的影响,并通过正交试验确定马铃薯营养鲜湿面制备工艺;此外,比较不同配方制备的鲜湿面的消化特性和血糖生成指数。结果正交试验和验证试验结果表明,马铃薯鲜湿面在水添加量30%,马铃薯全粉添加量6%,芦笋粉添加量4%,魔芋胶添加量0.8%或0.4%时,面条的蒸煮特性和质构特性无显著差异(P>0.05),都可用于鲜湿面的制备;对比不同配方制备鲜湿面的拉伸强度、蒸煮断条率无显著差异(P>0.05),不同方法制备鲜湿面血糖生成指数均大于80,都属于高生糖指数食品。结论通过工艺优化确定了马铃薯鲜湿面最优配方,在此配方下制备的面条具有良好的蒸煮特性和质构特性,本研究可为生产马铃薯鲜湿面提供理论依据。

石莼发酵条件优化及其在刺参养殖中的应用效果

为优化石莼(Ulva lactuca)发酵饲料工艺并探索石莼发酵饲料对刺参(Apostichopus japonicus)生长、消化性能的影响,选取特基拉芽孢杆菌(Bacillus tequilensis)作为发酵剂,以发酵产物中还原糖、游离氨基酸和多肽为评价指标,采用单因素试验与响应面法对石莼发酵工艺条件进行优化,并进一步比较石莼发酵饲料、石莼未发酵干粉饲料和商品饲料对刺参生长性能、消化性能的影响。结果表明:石莼最佳发酵条件为温度33℃、接种菌量4.4×10^(6)CFU/g、含水率50%,此条件下发酵7 d,产物中游离氨基酸由3.6 mg/g增加到45.0 mg/g,多肽含量由30.1 mg/g增加到96.0 mg/g,还原糖含量由1.3 mg/g增加到20.8 mg/g;用3组饲料投喂刺参30 d后发现,刺参对3组饲料的摄食率无显著性差异(P>0.05),石莼发酵饲料组饲料转化率及消化酶活性均显著高于其他两个饲料组(P<0.05),刺参增重率与商品饲料组相差不大(P>0.05),但显著高于石莼未发酵干粉饲料组(P<0.05)。研究表明,石莼发酵饲料可替代商品饲料,不仅能提高刺参增重率、消化酶活性,同时也为刺参饲料的配制提供了广泛的原料资源。