Effect of processing on potato starch: in vitro availability and glycaemic index

The content of digestible starch (DS) and resistant starch (RS) in processed potatoes was assessed. In addition, the effect of domestic cooking on the in vitro digestibility of starch in this tuber, which may influence the glycaemic response, was studied. Resistant starch in raw potato is high, however different RS values were obtained when processed, ranging from 1.18% in boiled potatoes to 10.38% in retrograded flour. In general, cooked potatoes have high levels of DS. Starch digestibility is improved after processing and it is affected by the cooking methods. Boiled and mashed potatoes showed the highest rate of digestion, on the contrary raw potato was hardly digested. The estimated Glycaemic Index (GI) from the degree of starch hydrolysis within 90 min was in accordance with the reported GI values, for potatoes processed in the same way.     

发酵法制备马铃薯微孔淀粉的工艺优化

采用黑曲霉直接发酵法制备马铃薯微孔淀粉.在单因素研究的基础上,采用正交试验优化发酵工艺条件.结果表明,在30℃,摇床转速170r/min条件下,初始PH为5.5,豆饼粉4%,接种量3%,添加初始马铃薯生淀粉10%,发酵40 h后,补加10%生淀粉,后期发酵45 h,制得微孔淀粉吸附性能较佳,吸水率和吸油率分别比原淀粉提高了62.8%和69.2%.     

纤维素酶-压热法制备马铃薯抗性淀粉工艺参数优化

为了提高抗性淀粉的得率,并获得抗性淀粉制备方法的最佳工艺参数,该试验以马铃薯淀粉为原料,抗性淀粉得率为评价指标,采用纤维素酶-压热法制备马铃薯抗性淀粉。研究淀粉乳浓度、酶添加量、酶解时间、压热温度、压热时间5个因素对马铃薯抗性淀粉得率的影响,在单因素试验的基础上,通过正交试验优化得出马铃薯抗性淀粉的最佳制备工艺条件,即淀粉乳含量25%、淀粉乳pH 5.0、酶用量30 U/mL、酶解时间50 min、压热温度125 ℃、压热时间30 min、老化温度4 ℃、老化时间18 h,在此条件下抗性淀粉的得率为30.33%。     

马铃薯淀粉的提取与直链淀粉的制备

为解决商品淀粉成本高的问题,以绵阳本地鲜马铃薯为原料,通过设计正交实验研究马铃薯淀粉提取工艺,以马铃薯淀粉得率为参考指标筛选出马铃薯淀粉提取最佳工艺参数为:粉碎时间2 min,静置时间3 h,洗涤次数3次。在最佳工艺条件下,鲜马铃薯的平均淀粉得率为13.5%。以国标法为基础,采用热碱法和正丁醇-异戊醇结晶法制备直链淀粉纯品,对其进行品质鉴定,结果表明实验室自制的直链淀粉可以作为标准品使用。      

响应面优化微波法制备马铃薯交联淀粉工艺

交联淀粉不仅具有预防和治疗疾病的健康效应,还是良好的稳定剂与增稠剂。为优化交联淀粉的制备工艺,采用单因素和响应面试验对微波法制备马铃薯交联淀粉的工艺进行优化。单因素试验结果表明,六偏磷酸钠质量分数、淀粉乳质量分数、p H、温度对交联淀粉的沉降积均有显著影响。在单因素试验的基础上,采用响应面法构建交联淀粉沉降积的回归方程。结果表明,回归方程的决定性系数R2为0.9806,表明该模型能够较好的预测交联淀粉的沉降积;优化结果表明,当六偏磷酸钠质量分数0.6%(相对于淀粉干基),淀粉乳质量分数24%,p H为10,温度为44℃时,交联淀粉的沉降积为4.86 m L,实测值与回归模型的预测值的相对误差1%。说明采用响应面法得到的优化工艺准确性高。     

辛烯基琥珀酸马铃薯淀粉酯的制备条件研究

以马铃薯淀粉为原料,采用单因素和正交实验方法研究湿法工艺制备马铃薯辛烯基琥珀酸淀粉酯,从淀粉乳的初始浓度、反应温度、酸酐浓度、pH和时间五个方面研究马铃薯辛烯基琥珀酸淀粉酯最佳制备工艺。其结果为:淀粉乳浓度40%、温度30℃、pH7.5~8.0、酸酐浓度5%。      

Effect of pre-soaking treatments on the nutritional profile and browning index of sweet potato and yam flours

The use of sweet potato and yams for product development is hindered by the discoloration from enzymatic and non-enzymatic browning. The effect of pre-soaking treatments on the nutritional changes and browning index (BI) of sweet potato and yam (greater yam and white yam) flours was investigated. Ascorbic acid (AsA), citric acid (CA), acetic acid (AA) and sodium metabisulfite (SMS) were used for soaking at three concentrations (0.25%, 0.50% and 1.00%) and two durations (1 h and 2 h). AsA and SMS removed more starch during soaking of sweet potato, while CA and AA removed more starch from greater yam and CA removed more starch from white yam. Highest removal of reducing sugars was observed in sweet potato in AA, while CA removed maximum reducing sugars from both the yams. Phenol and total free amino acid (TFA) levels were more in SMS treatment than the control sweet potato flour, and least in AA (2 h). Whilst AsA raised the phenols and TFA in greater yam, it removed phenols to the maximum in white yam. Maximum BI was in AsA treatment for the three crops, and least for flour from CA (0.25%) treated yams and AA (1.00%) treated sweet potato.Industrial RelevanceBrowning resulting from enzymatic and non-enzymatic reactions is a major drawback in the processing of sweet potato and yams for product development. The study showed that this could be successfully tackled through soaking the slices in low cost chemicals like acetic acid or citric acid and sodium metabisulfite at low concentrations. The treated slices yielded flour with very low browning indices compared to the respective native flours, which could enhance the potential of such flours in the development of food products.     

微波法合成交联马铃薯淀粉的工艺研究

以马铃薯淀粉为原料,三偏磷酸钠为交联剂,在微波辐射条件下制备交联淀粉。以结合磷为评价指标,探讨了微波加热时间、pH、淀粉质量分数和三偏磷酸钠的用量四个因素对交联马铃薯淀粉交联度的影响。通过单因素和正交试验,获得微波法制备交联马铃薯淀粉的较佳工艺参数为:马铃薯淀粉质量分数为30%,三偏磷酸钠用量为淀粉质量(干基)的0.3%,反应pH 10,时间4min。在此条件下制得结合磷含量为0.0305%的交联马铃薯淀粉。分别采用扫描电镜和红外光谱仪对产品结构进行表征。扫描电镜显示淀粉颗粒表面受到侵蚀,部分颗粒出现凹陷,红外光谱图显示在1050 970cm-1处P=O吸收峰加强,证明淀粉确实发生了交联反应。     

马铃薯羟丙基淀粉的制备及理化特性研究

研究了用环氧丙烷制备马铃薯羟丙基淀粉的反应条件及羟丙基化对马铃薯淀粉糊特性的影响.在反应条件中,着重研究了 Na2SO4用量、环氧丙烷用量、反应温度和反应时间对分子取代度的影响规律.实验表明:羟丙基化能大大提高马铃薯淀粉糊的透明度、膨胀度和冻融稳定性,适度降低了糊化温度.     

菠萝蜜种子杂粮冲调粉工艺及血糖生成指数研究

目的 以菠萝蜜种子和低血糖生成指数(glycemic index,GI)杂粮为主要原料制作冲调粉,研究蒸制、水煮、烘烤3种熟化工艺和真空冷冻干燥、热风干燥、喷雾干燥3种干燥方法对其血糖生成指数及风味物质的影响.方法 采用快速体外淀粉消化法测定淀粉水解率并计算估计血糖生成指数(expected glycemic inde...     

一种新型复合微生态制剂的研制

采用双歧杆菌,蜡样芽孢杆菌及低聚果糖制成一种新型复合微生态制剂,在温度25℃,干燥条件下其活菌数保持基本稳定的时间为12个月,毒理实验表明其安全无毒。     

马铃薯葡萄糖培养基制作方法的改进

对传统马铃薯葡萄糖培养基制作方法进行改良,以期得到一种制作简便、经济节约、对酵母菌检出率较高的马铃薯葡萄糖培养基。将马铃薯葡萄糖培养基制作方法改进为直接打浆、免除过滤的方式,通过对马铃薯浓度筛选实验、酵母菌性能测定实验以及酵母菌检出率实验检验改良马铃薯浓度培养基性能。结果表明最佳的马铃薯浓度为100g/L,与传统马铃薯葡萄糖培养基相比,在该浓度下对酵母菌的性能没有显著影响;改进后的培养基与传统方法制作的培养基相比,能够提高酵母菌检出率67.2%,t检验法分析二者有显著性差异。说明改进后的培养基相比传统的马铃薯葡萄糖培养基可达到节约制作时间、节省材料,并且在提高酵母菌检出率上性能更为优越。     

Effect of sperm preparation method on in vitro fertilization in pigs

This study was designed to determine the effect of different sperm preparation treatments before IVF on the acrosome reaction, oocyte penetration time, early embryo development and timing of female and male pronucleus formation. Pooled sperm-rich fractions were (i) washed in PBS, (ii) left unwashed, or (iii) layered in a Percoll gradient. In Expt 1, the proportion of acrosome-reacted spermatozoa, determined by staining with fluorescein isothyocyanate-labelled peanut agglutinin lectin and propidium iodide, was highest after treatment with Percoll (P < 0.001). In Expt 2, oocytes matured in vitro were co-cultured with spermatozoa for 2, 4 or 6 h. Attached spermatozoa were then removed and the oocytes were cultured in fresh IVF medium for 16 h. Both sperm treatment and co-culture time were found to affect penetrability and monospermy rates (P < 0.001); spermatozoa treated with Percoll showed fastest oocyte penetration and highest penetrability. In Expt 3, matured oocytes were co-incubated with spermatozoa pretreated by the three above mentioned procedures (i, ii, iii) for 2, 6 and 2 h respectively. Putative zygotes were then washed and transferred to medium NCSU-23 until the blastocyst stage. In this experiment, sperm treatment had a significant effect on the cleavage rate (P < 0.001) and rate of blastocyst formation (P < 0.05); the group treated with Percoll showed the highest rate of blastocyst formation. Finally, in Expt 4, timing of female and male pronucleus formation for each sperm treatment was determined 4, 6 and 8 h after insemination. The time of female and male pronucleus formation was affected by the sperm treatment and was faster for the Percoll group (P < 0.05). The findings of the present study indicate that treatment with Percoll yields the best results in this in vitro pig embryo production system.     

谷氨酸制备马铃薯交联淀粉研究

以谷氨酸作交联剂制备马铃薯交联淀粉,对其制备条件进行研究,考察影响其交联效果因素。结果表明,谷氨酸制备马铃薯交联淀粉工艺条件为:谷氨酸用量5%、pH为8、反应温度45℃、反应时间90 min,在该条件下,制备马铃薯交联淀粉交联度最高。     

马铃薯表皮脱净率测定方法的研究

文章提出了一种像素比值测定法,并通过模型验证的方法设计了3种不同马铃薯模型和3种不同表皮脱净率的正交试验进行验证。试验结果表明,在95%的置信区间内,马铃薯模型的实际测定值与理论计算值之间无显著性差异,说明提出的像素比值测定法在计算马铃薯表皮脱净率问题上具有较强的可信度,该方法用于评价马铃薯的去皮效果是科学可行的,可作为马铃薯产品品质鉴定的一种有效方法。     

一步和二步改性法对交联酯化甘薯淀粉性质的影响

以三偏磷酸钠(STMP)为交联剂,醋酸酐为酯化剂,对甘薯淀粉进行复合变性,通过一步和二步改性法制备交联酯化改性甘薯淀粉。比较了一步和二步改性法对交联酯化甘薯淀粉性质的影响。一步法指甘薯淀粉交联后调整酯化的条件,省去水洗、中和与干燥操作工序连续进行酯化;二步法为将制备的交联淀粉粉碎干燥后作为酯化变性反应的原淀粉。以峰值粘度和稳定性为指标测定。结果表明:一步法改性的交联酯化甘薯淀粉具有更好的峰值粘度和稳定性;二步法改性的交联酯化甘薯淀粉具有更好的抗凝沉性,溶解度和膨胀度略高于一步法,抗冻融性更好,但与一步法差别不显著。     

Relationship between glycaemic index and nutrient composition of fruit and vegetables

Abstract

The glycaemic index (GI) of different fruits and vegetables varies over a three‐fold range but no causal explanation for the differences has been advanced. This study examined the statistical relationship between published data on GI and the concentrations of nutrients in 24 fresh fruit and vegetables. The most significant relationships were a decrease in GI with increasing organic acids, especially malic acid, and the monosaccharides glucose and fructose, and an increase in GI with increasing minerals. There was no significant correlation with sucrose, starch, citric acid, protein, fat or vitamin C. Possible part explanations for the findings is the GI is reduced by compositional changes that result in an increase in osmolality and nutrient concentration which delay gastric emptying. It is also suggested that acidity per se, i.e. pH, may have a direct effect on GI.