Some physicochemical properties of acha (digitaria exilis stapf) and iburu (Digitaria iburua stapf) grains

Some physicochemical properties of two cultivated species of Digitaria (D exilis and D iburua) were studied. Physical properties such as 1000-kernel weight, kernel size and water absorption rate of the grains were determined. Water absorption by both cereals reached a maximum after 24 h steeping. The starch from both cereals exhibited a two-stage pattern of swelling and solubility properties similar to other non-waxy cereal starches. Starch from acha swelled less than iburu, 7·3 compared with 7·8 for iburu. Chemical constituents such as protein, oil, crude fibre, ash, nitrogen-free extract and amylose were also determined. An amylose content of 280 g kg^?1 was obtained for both cereal starches. Brabender amylograms obtained from starch and flour were typical of most normal, non-waxy cereals. Maize starch had relatively higher hot-paste and cold-paste viscosities than starches of the two Digitaria species.     

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.     

Effect of roasting parameters on soy‐butter product quality

Effect of roasting temperature and time on the hardness, moisture content and colour of whole‐kernel of soybean was studied using response surface method (RSM). Colour of reference soy‐butter (RSB) was used to indicate the time and temperature suitable for roasting soybean kernels to prepare soy‐butter (SB). Temperature (160 °C) and time (90 min) for roasting were identified, soybean kernels were roasted, subsequently made into SB and compared with RSB on the basis of nutrient content, particle size, colour and rheology. SB contained 45 g% protein and 34 g% fat on dry matter basis. There was a significant difference (P < 0.05) between RSB and SB on the basis of L* values, D_3,2 and D_4,3. Rheology showed that SB samples behaved like a viscoelastic material. The mean apparent viscosity was significantly different (P < 0.0001) between SB (7.18 Pa.s) and RSB (4.72 Pa.s) which may be due to the significant difference in the particle size distribution (PSD). The Herschel‐Bulkley model could successfully explain the rheological behaviour of SB.     

Response surface optimisation of extraction of antioxidants from strawberry fruit, and lipid peroxidation inhibitory potential of the fruit extract in cooked chicken patties

BACKGROUND: Strawberries contain high levels of antioxidants and have beneficial effects against oxidative stress‐mediated diseases, such as cancer. They contain multiple phenolic compounds, which contribute to their biological properties. Hence, a study was carried out to optimise the extraction of antioxidants and evaluate the antioxidant potential of strawberry fruit extract (SE) in cooked chicken patties during refrigerated storage. The activity of SE was compared with that of butylhydroxytoluene (BHT). RESULTS: The effect of solvent type (MeOH and EtOH), concentration (0–70%) of EtOH in the system, temperature (30–60 °C), and time (30–150 min) on DPPH^?‐scavenging activity of SE was investigated. Response surface methodology was used to estimate the optimum extraction conditions for each parameter. The maximum predicted DPPH^? scavenging under the optimised conditions (100% MeOH, 30 °C, 150 min) was 43% at 1 mg SE mL^?1. Freshly prepared chicken patties were treated with 5% and 10% SE and 2% BHT, and stored aerobically at 4 °C for 6 days. SE had no influence (P < 0.05) on any of the sensory attributes of the patties. The values of thiobarbituric acid reactive substances reduced significantly (P < 0.05) from 2.47 mg in control patties to 0.312 mg and 0.432 mg malonaldehyde kg^?1 sample in 5‐SE and 10‐SE patties, respectively, on the day 6 of storage. CONCLUSION: The optimised model depicted MeOH at 30 °C with an extended time of 150 min as the optimum settings for extraction of compounds from strawberry that had the scavenging activity. The study shows that the extraction of natural antioxidants from strawberry can be improved by optimising several key extraction parameters. SE also acted as an effective antioxidant and suppressed lipid peroxidation in cooked chicken patties. Copyright © 2011 Society of Chemical Industry     

响应曲面法优化酸性电解水对鲜切苹果杀菌效果的影响

以微生物减菌率为评价指标,在单因素试验的基础上,采用中心组合设计法,研究NaCl质量浓度、处理温度、处理时间,以及料液比对接种金黄色葡萄球菌、大肠杆菌、沙门氏菌和单增细胞李斯特菌的鲜切苹果杀菌效果的影响。响应面分析结果表明,鲜切苹果减菌工艺最优条件为:NaCl质量浓度4.5 g/L,处理温度25℃,处理时间6.45 min,液料比6∶1(m L/g),在此条件下经处理后细菌总数由1.14×105CFU/g降为9.3×103CFU/g,减菌率可达91.84%。同时,该处理对鲜切苹果的p H值和可溶性固形物影响不大,且能较好地抑制维生素C的降解及其表面的褐变。     

响应曲面法优化芦荟蒽醌提取工艺的研究

采用响应曲面法的中心组合设计对超声波辅助提取库拉索芦荟中的蒽醌类物质的提取工艺参数进行优化研究。考察提取时间、液料比、乙醇浓度、超声功率对芦荟蒽醌提取率的影响,并建立数学模型。利用Minitab软件对数据进行回归分析,得到芦荟蒽醌提取率的二次多项式回归方程的预测模型。结果表明,库拉索芦荟蒽醌超声辅助提取的优化工艺条件为:提取时间40min,液料比50:1(mL/g),乙醇浓度80%,超声功率600W。在此条件下,库拉索芦荟全叶烘干粉中蒽醌类物质的提取率为2.868%。     

响应面分析法优化血红素提取工艺

在单因素试验的基础上,通过中心组合旋转设计与响应面分析法优化酸性丙酮法提取血红素的工艺,考察浸提时间、酸酮比以及酸性丙酮与血红蛋白的比对血红素得率的影响,并通过响应面分析法得出最佳提取条件。结果表明：最佳提取工艺条件为浸提时间42min、酸酮比3%、酸性丙酮与血红蛋白体积比5.66:1,在此条件下血红素的得率为0.225g/100mL,与预测值0.230g/100mL 相差不显著。     

Effect of cold shock on the enhancement of β‐amylase activity during malting and malt processability for a red sorghum intended for brewing use

The low β‐amylase activity of sorghum malt is a major concern when malts are intended for use in brewing. Several studies have shown that the germination temperature plays an important role in β‐amylase synthesis. In this study, the cold shock treatment was envisioned as a means of improving β‐amylase synthesis during red sorghum malting. The results show that, when a high‐frequency decrease in the germination temperature is used, the obtained malt exhibits a significantly increased β‐amylase activity. This study shows that this increase is not sufficient to consider cold shock as a means of improving β‐amylase activity for red sorghum brewing use, as the processabilty of the malts is unsatisfactory. Copyright © 2015 The Institute of Brewing & Distilling     

星点设计- 效应面法优选短梗五加叶中金丝桃苷的提取工艺

目的：星点设计- 效应面法优选短梗五加叶中金丝桃苷的提取工艺。方法：以乙醇体积分数、提取时间、溶媒比为主要影响因素,金丝桃苷提取率为评价指标,通过对主要因素各水平的多元线性回归及二项式拟合,用岭嵴分析和效应面法选取最佳工艺,并进行预测分析。 结果：确定金丝桃苷最佳提取工艺为乙醇体积分数69.80%,溶媒比23.17,超声提取时间86.56min。结论：星点设计- 效应面法优选的短梗五加叶中金丝桃苷的提取工艺,方法简便,精密度高。     

Optimization of Malting Conditions for Two Black Rice Varieties,Black Non‐Waxy Rice and Black Waxy Rice (Oryza sativa L. Indica)

Two black rice varieties, “black non‐waxy” and “black waxy”, were investigated as possible raw materials for the production of malt. The malting conditions were optimised using response surface methodology. The three process parameters were steeping, germination time and temperature. Each parameter was tested at three levels: adjustment degrees of steeping were 38, 41, and 44%, germination times were 6, 7, and 8 days, and the temperatures were 20, 25 and 30°C. At the end of the germination process, all samples were kilned at 50°C for 24 h, and shoot/rootlets were removed before a detailed quality assessment was performed. Data analysis was performed using the Design Expert Statistic Program. The optimal conditions found for both rice varieties were as follows: germination time of 8 days at 30°C and 44% grain moisture. Although the extract yield, and a‐amylase and β‐amylase activities of both rice malts were lower than barley malt, the higher activity of limit‐dextrinase enzyme and apparent attenuation limit (AAL), which was higher than 80%, suggests that rice malt has potential for use in brewing.     

极低频电磁场影响Nisin发酵生产的工艺研究

在发酵罐的外部循环管路上加螺线圈,通过控制磁场的强度、发酵液的循环速度和磁场的暴露时间3个因素来对磁场存在下Nisin的发酵进行研究并寻求其最优工艺.采用响应面法中的中心组合试验设计法得到3个因素的最佳条件,通过对试验数据的分析,在最优条件电流0.43A,气速0.56L/min,暴露时间7 h时,Nisin效价提高27%.     

中心组合设计优化酶法提取胖大海多糖工艺

利用中心组合设计及响应面分析法对胖大海多糖的纤维素酶提取工艺条件进行了优化。在单因素实验的基础上,选取纤维素酶浓度、料液比和酶解时间进行了中心组合实验设计,并运用DesignExpert8.06软件对数据进行分析和优化。结果表明,影响胖大海多糖得率的工艺参数按主次顺序排列为:纤维素酶添加量>酶解时间>料液比,最佳提取条件为:纤维素酶添加量1.92%,料液比1∶30.5,pH4.8,50℃下酶解时间126min,在此条件下,胖大海多糖得率为7.92%±0.09%。      

酶辅助提取紫甘蓝中原花青素的工艺优化

以紫甘蓝为原料,在单因素实验基础上,通过中心组合设计和响应面分析法,对酶辅助提取紫甘蓝中原花青素的条件进行研究。确定酶辅助提取的最佳工艺条件是：酶解时间2.5h,酶解温度43.39℃,纤维素酶浓度0.02%,果胶酶浓度0.02%,在此工艺条件下,原花青素的提取率为17.3%。     

Original article: Optimisation of extraction conditions and characteristics of skin gelatin from Nile tilapia (Oreochromis niloticus)

Response surface methodology was used to optimise gelatin extraction conditions from the skin of Nile tilapia (Oreochromis niloticus), and characteristics of the gelatin were determined. Concentration of NaOH (%, X₁), alkaline treatment time (h, X₂), concentration of HCl (‰, X₃) and acid treatment time (min, X₄) were chosen for independent variables. Dependent variable was yield of gelatin (%, Y). Optimal conditions were X₁ = 3.2 (%), X₂ = 2.3 (h), X₃ = 0.7 (‰) and X₄ = 84 (min), and predicted value of response optimal conditions was Y = 20.4%. Actual value was 19.3% by verification experiments under optimal conditions. Crude protein content of the tilapia skin gelatin was 88.5%. The content of imino acids including proline and hydroxyproline in the gelatin was 185 residues per 1000 total amino acid residues. Its gel strength was 260 g. The gelling and melting points were 18.0 and 22.4 °C, respectively.     

Multiple responses optimization of antioxidative components extracted from distiller's grains using response surface methodology and identify their chemical compositions

Distiller's grains are a waste product in the Baijiu brewing that contains many bioactive ingredients. However, few studies on the active ingredients and biological in distillers' grains. Therefore, it is promising to study the utilization of bioactive substances in distiller's grains. In our present study, an ultrasonic-assisted method was applied to extract antioxidative components from distiller's grains. Four factors: ethanol concentration, liquid–solid ratio, extraction temperature, and ultrasonic power were selected, and multiple responses were studied using response surface methodology (RSM). The effects of factors and the correlation between all responses (flavonoids content, DPPH assay, OH^- assay) were investigated. The regression model indicated that all factors have significant effects on all responses. The model predicted a flavonoid yield of 6.53 mg/g, DPPH-RSC of 90.00%, and OH-RSC of 55.03% at an ethanol concentration of 69%, a liquid–solid ratio of 35 ml/g, an extraction temperature of 61℃, and a power of 300 W. The confirmation test showed the closeness of the predicted results with those of experimental values. The distiller's grains was separated by LH20 glucan gel, and total flavonoid content of 79.4% was obtained. LC-HRMS analyzed the compounds, and 24 compounds, including 7 flavonoids, were identified successfully.     

响应面法优化花椒香气成分的HS-SPME萃取条件的研究

为了优化花椒香气成分HS-SPME萃取,在单因素实验的基础上,利用Box-Benhnken的中心组合实验设计原理,以提取物质的质(色)谱图总峰面积为考察指标,对萃取温度、萃取时间、原料用量进行3因素3水平响应面分析。结果表明,萃取温度对总峰面积有显著影响,萃取时间和原料用量对其影响不显著;萃取时间和原料用量的交互作用显著,其它交互作用均不显著;得到萃取花椒香气成分最佳的工艺条件为:萃取温度55.97℃,萃取时间30.73min,原料用量3.15g,在此条件下,香气成分总峰面积为2.21101×109。     

响应面分析法优化大豆11S球蛋白提取工艺条件

从提取溶剂及提取条件等方面对大豆抗原蛋白提取工艺进行了优化,采用单因素试验对提取溶剂及提取条件进行了分析研究,结果表明Tris-HCl缓冲液是理想的提取溶剂,提取温度、提取时间和料液比对大豆抗原蛋白提取产生一定的影响,其中提取温度的影响最为显著。通过Box-Benhnken中心组合设计和响应面分析法,确定了大豆抗原蛋白提取的理想工艺条件,即Tris-HCl缓冲液为溶剂,料液比1∶21.2(g∶mL),提取温度19.15℃,提取时间1.085h,在此条件下最大吸光度值为1.220,验证值为1.198,11S球蛋白提取得率为24.45%,较优化前提高了76.15%。     

Production of α‐amylase by Aspergillus oryzae As 3951 in solid state fermentation using spent brewing grains as substrate

BACKGROUND: The optimisation of nutrient levels for the production of α‐amylase by Aspergillus oryzae As 3951 in solid state fermentation (SSF) with spent brewing grains (SBG), an inexpensive substrate and solid support, was carried out using response surface methodology (RSM) based on Plackett–Burman design (PBD) and Box–Behnken design (BBD). RESULTS: In the first optimisation step a PBD was used to evaluate the influences of related factors. Corn steep liquor, CaCl₂ and MgSO₄ were found to be the most compatible supplements to the substrate of SBG and influenced α‐amylase activity positively. In the second step the concentrations of these three nutrients were optimised using a BBD. The final concentrations (g/g dry substrate basis) in the medium optimised with RSM were 1.8% corn steep liquor, 0.22% CaCl₂ and 0.2% MgSO₄ · 7H₂O using SBG as the solid substrate. The average α‐amylase activity reached 6186 U g^?1 dry substrate under the optimised conditions at 30 °C after 96 h. Under the optimised conditions of SSF an approximately 17.5% increase in enzyme yield was observed. CONCLUSION: SBG was found to be a good substrate for the production of α‐amylase by A. oryzae As 3951 under SSF. Copyright © 2007 Society of Chemical Industry     

Optimisation of pectin acid extraction from passion fruit peel (Passiflora edulis flavicarpa) using response surface methodology

Pectin was extracted from passion fruit peel using three different acids (citric, hydrochloric or nitric) at different temperatures (40–90 °C), pH (1.2–2.6) and extraction times (10–90 min), with and without skins using a 2⁴ factorial design. Temperature, pH and extraction time had highly significant effects on the pectin yield. A central composite design with face centring was used to optimise the extraction process conditions for citric acid without skins. Pectin yields varied from 10% to 70%. The optimal conditions for maximisation of pectin yield were the use of citric acid at 80 °C and pH 1 with an extraction time of 10 min considering model extrapolation.     

罗伊氏乳杆菌培养基优化及其生长代谢研究

罗伊氏乳杆菌的MRS 培养基是富培养基,简化培养基组分,优化培养基组成和培养条件是微生物工业化培养的重要基础。本实验在传统MRS 培养基基础上,首先对氮源进行单因素优化,然后采用Plackett-Burman 和中心组合试验设计对影响罗伊氏乳杆菌CG001 生长的MRS 培养基和培养条件进行筛选优化,并在最优条件下研究该菌的生长代谢情况。结果表明：酵母膏质量浓度、葡萄糖质量浓度、硫酸锰质量浓度和温度是影响菌体质量浓度的4 个关键因素;经响应面法分析确定该菌的最优培养条件为：酵母膏质量浓度20g/L,葡萄糖质量浓度20g/L,醋酸钠质量浓度7g/L,柠檬酸铵质量浓度1g/L,磷酸氢二钾质量浓度3g/L,硫酸镁质量浓度0.2g/L,硫酸锰质量浓度为0.23g/L,吐温-80 质量浓度1g/L,初始pH6.2,培养温度38.6℃,最终菌体质量浓度达0.984g/L,相对优化前提高1.102 倍。发酵罐中菌体生长曲线呈S 型,4～12h 菌体处于对数生长期,之后趋于平衡,葡萄糖的代谢与菌体的生长速率相对应。