Effect of partial substitution of wheat flour with resistant starch on physicochemical,sensorial and nutritional properties of breadsticks

This study determined the physicochemical, sensorial and nutritional properties of breadsticks to which a resistant starch (RS)-rich ingredient was incorporated by partial substitution, that is, 40%–70%, of hard wheat flour in the control recipe. Wheat flour substitution at the levels exceeding 50% lightened the colour while decreasing the moisture content and hardness of breadsticks, which was explainable by the microstructure. Changes in properties of breadsticks also affected the suitability of its sensory attributes, particularly colour and texture. Breadsticks, of which half of wheat flour was substituted, contained less protein and calories but higher carbohydrate than the control formula. Such flour substitution increased RS content closed to its effective dose of 15 g in a 45-g serving, which led to approximately 15% reduction in in vitro glycaemic index. Therefore, incorporating effective dose of RS in breadsticks could be performed, without causing substantial changes in product quality, by partial substitution of wheat flour.     

Effects of potato starch on the characteristics,microstructures and quality attributes of indica rice flour and instant rice noodles

The effects of partial replacement (0%–20%, w/w) of rice flour by potato starch (PS) on the physicochemical properties, microstructures, texture and in vitro digestibility of indica rice flour (IRF) and instant rice noodles (IRN) were systematically investigated. Accordingly, the addition of PS significantly increased the peak viscosity (2876.00–3221.00 mPa·s) and tan δ values (0.14–0.22) but lowered the setback values (2169.00–1036.50 mPa) of the pastes. Rice noodles with 5%–15% PS (PS and IRF at the mixing ratios of 5:95, 10:90, 15:85 and 20:80, respectively) addition exhibited modulated appearance and textural properties. The mutually exclusive phosphate groups of PS facilitated the expansion of starch granules, contributing to the formation of more compact microstructure and higher-ordered crystalline structures (confirmed by scanning electron microscope and X-ray diffraction), endowing rice noodles with better cooking and digestive attributes, and visibly increased slowly digestible starches content (26.09%–31.34%). The quality attributes of rice noodles could be accurately predicted by the physicochemical properties of rice flour referring to Pearson’s correlation analysis. The study demonstrates that the blending of PS is both an effective and economical pathway in improving the nutritional and textural properties of IRN.     

马铃薯-小麦粉混粉的理化性质与消化特性研究

以不同比例马铃薯全粉(PG)和小麦粉(WF)混粉为研究对象,探讨了马铃薯全粉与小麦粉混合比例对混粉还原糖、溶解度、膨胀度、冻融稳定性、糊化特性、快消化淀粉含量、慢消化淀粉含量、抗性淀粉含量及消化速率的影响。结果表明,马铃薯全粉具有较低的还原糖含量,较高冻融稳定性、糊化温度、快消化淀粉含量和消化速率。小麦粉的慢消化淀粉和抗性淀粉含量较高,消化速率较低。马铃薯全粉与小麦粉比例为9∶1时,溶解度和膨胀度最高。比例为1∶9时,糊化温度最低。马铃薯全粉和小麦粉的混合比例对混粉的理化性质及消化特性有明显影响。      

马铃薯主粮化与马铃薯全粉及其生产线

马铃薯不但营养价值高,富含膳食纤维以及人体必需的多种氨基酸,而且脂肪和糖分含量又低。推进马铃薯主粮化,就是将马铃薯加工成适合国人消费习惯的馒头、面条、米粉,实现由副食消费向主食消费转变,逐渐成为稻谷、小麦、玉米之后的第四大主粮。这既有利于改善全体国民膳食结构,又有利于提高人民健康水平。马铃薯全粉及马铃薯全粉生产线将是实施马铃薯主粮化的一把金钥匙。      

醋酸酯变性淀粉对荞麦挂面烹煮、质构特性的影响

以荞麦-小麦混合粉为原料,研究木薯醋酸酯淀粉、马铃薯醋酸酯淀粉在不同添加量下对荞麦挂面品质的影响。两种醋酸酯淀粉均可显著降低荞麦挂面的烹煮损失,提高吸水率(p<0.05)。两种醋酸酯淀粉的添加量与荞麦挂面硬度、内聚性、胶着性极显著负相关,而与荞麦挂面的弹性呈极显著正相关,但与咀嚼性无显著相关性。     

Effects of cooking, drying and pretreatment methods on texture and starch digestibility of instant rice

Instant rice produced from a conventional process consisting of the cooking, washing and drying steps possesses poorer eating quality compared with that of freshly cooked rice. The objective of this work was therefore to study the effects of cooking, pretreatment and drying methods on microstructure, textural properties and starch digestability of instant rice after rehydration; jasmine white rice was chosen as a test material. Conventional boiling method and electric rice cooking were selected as the methods to prepare cooked rice. In the case of boiling, cooked rice was frozen at −20 °C or cooled at 4 °C for 24 h prior to drying, while the cooked rice from an electric rice cooker was washed with ambient or cool water for 30 s prior to drying. After pretreatment the cooked rice was dried either by freeze drying or hot air drying at 80 °C. Based on the scanning electron microscopic results it was found that the cooking, pretreatment and drying methods all affected the rice morphology. The hardness and stickiness of instant rice after rehydration were lower for samples prepared from the rice cooker than those of freshly cooked rice, while both textural properties appeared to be improved significantly for the samples from boiling. The texture of the freeze-dried products was not different from that of the air-dried one. The freezing pretreatment provided the texture and glycemic index of instant rice after rehydration similar to those of the freshly cooked rice. On the other hand, the cooling pretreatment resulted in the harder texture and higher glycemic index of the samples.     

螺杆挤压对马铃薯淀粉消化性及血糖指数的影响

目的研究螺杆挤压对马铃薯淀粉消化特性的影响。方法马铃薯淀粉经过螺杆挤压后(过程中淀粉未膨化),采用酶重量法测定挤压后抗性淀粉的含量变化情况,并通过模拟体外消化和动物实验评价挤压后淀粉的消化性能和餐后血糖上升速率。结果螺杆挤压后马铃薯淀粉中抗性淀粉的含量增加了1.08%,酶解时间为0~1.5 h时,马铃薯淀粉快速消化淀粉的含量减少,酶解时间为1.5~6.5 h时,抗性淀粉和慢消化淀粉的含量增加。挤压后的马铃薯淀粉在一定程度上可以降低小鼠的餐后血糖指数。结论螺杆挤压技术可以提高抗性淀粉和慢消化淀粉的含量,减缓餐后血糖上升速率,为马铃薯食品的深度开发提供一定的参考。     

紫薯-小麦混合粉的性质及在面条上的应用

紫薯全粉保留了鲜薯的色泽和营养,是极好的食品加工原料,能够弥补小麦粉营养结构单一的缺点。将紫薯粉添加到小麦粉中,对混合粉的特性及在面条上的应用进行了研究,结果表明：随着紫薯粉的添加量由0%增加到30%,混合粉的糊化温度由66.31℃上升至67.73℃;糊化黏度、崩解值和回生值均减小;面团稳定时间由18min下降至7.8min;紫薯面条煮沸损失率由7.2%上升至11.8%;最大拉伸应力、剪切应力及硬度均减小;面条色度变暗,色泽向紫红色渐变。紫薯粉最佳添加量为15%。     

Addition of waxy,low- or high-amylose rice starch differentially affects microstructure,water migration,texture and cooking quality of dried potato starch noodles

Potassium alum (PA) is commonly used as an improver for quality of potato starch noodles (PSN). However, PA poses health risks to consumers, thus making it imperative to seek substitutes for Al³⁺. In this study, effects of rice starch addition on quality of PSN were investigated. Scanning electron microscopy revealed that addition of low-amylose rice starch (LARS) or 40% waxy rice starch (WRS) enhanced structural development of PSN. Magnetic resonance imaging showed that the presence of LARS increased water retention in PSN. Addition of rice starch enhanced cooking quality of PSN by extending cooking time and significantly decreasing cooking loss (P < 0.05). Moreover, addition of LARS significantly (P < 0.05) increased tensile strength and hardness of PSN, whereas addition of WRS had the reverse effect. Mixing waxy potato starch with LARS at ratios of 4:1 or 3:2 is optimal for production of PSN.     

前处理和干燥对马铃薯全粉品质影响的研究进展

马铃薯全粉是新鲜马铃薯经去皮、切片、漂烫、护色等后脱水干燥制成的片状或粉末状产品,包含了除薯皮以外大部分马铃薯的营养物质,因此马铃薯全粉具有营养丰富、耐储的优点。作为马铃薯主粮化的原料,马铃薯全粉有助于改善和丰富我国居民膳食营养结构。近两年对马铃薯全粉的研究较多地集中在添加了马铃薯全粉制成的主食类或者其他相关产品的开发上。马铃薯全粉品质除了与马铃薯品种有关外还受到马铃薯全粉加工工艺的影响。本文将从马铃薯全粉生产过程中的前处理和干燥两个方面对马铃薯全粉品质的影响进行综述,以期为该领域的研究者提供理论参考。     

Physicochemical,antioxidant properties and in vitro digestibility of wheat–purple rice flour mixtures

The physicochemical characteristics, antioxidant properties and in vitro digestibility of high‐antioxidant content flours made from different combinations of Thai purple rice flour and refined wheat flour from 25%, 50% to 75% (w/w) were investigated and these were compared with whole flour from purple rice and refined wheat flour. The increase in substitution levels of purple rice flour affected all the functional properties of flours, at the same time the levels of dietary fibre, protein digestibility and antioxidant compositions were also changed. The purple rice flour exerted a particularly strong effect on starch digestibility as the purple rice increased to 50% in the mixture. Moreover, purple rice flour showed lower amounts of rapidly digested starch (RDS), whereas slowly digested starch (SDS) of whole flour from purple rice and 75% substitution purple rice flour was found to be the highest for all samples. The in vitro starch digestibility of all samples also showed a positive correlation between dietary fibre and antioxidant compounds. Overall, the addition of purple rice flour improved the final nutritional properties, notably a lower predicted glycaemic index, and a higher antioxidant potential, which are two important nutritional properties for human health.     

Delayed drying interval of red rice: Effects on cooking properties,in vitro starch digestibility and phenolics content

Maintaining the cooking characteristics and bioactive compound contents in red rice is essential during the post-harvest stages. For this reason, this study aimed to evaluate the influence of delayed drying time interval of 3 and 6 days and temperature of 15 and 25 °C followed by storage for 12 months on the cooking properties, in vitro starch digestibility, and the phenolic contents of red rice. The increased the delayed interval duration reduced the protein solubility, rehydration capacity, and free phenolic contents, and increased the cooking time and hardness after cooking in a temperature-independent manner. These changes reduced the starch digestibility of red rice. Increased the delayed interval duration also reduced the proanthocyanidin contents, consequently changing the grain color (decreased luminosity and increased a1 values). Thus, a delay in the interval duration before drying of 3 days at 15 °C showed the best results about the rice characteristics among the evaluated parameters; these conditions may be utilized when immediate drying is not possible.     

In vitro starch digestibility of fresh and sun‐dried faba beans (Vicia faba L.)

Fresh and sun‐dried faba beans (Vicia faba L.) were cooked, stored for various times at 4 °C and analysed for available starch (AS), resistant starch (RS) and fibre‐associated resistant starch (FARS) contents as well as α‐amylolysis. Fresh beans required a shorter cooking time (25 min) than dried beans (158 min). Cooked fresh faba beans had a higher AS content than cooked dried faba beans. The AS content in both decreased during cold storage, with fresh beans showing a smaller decrease than dried beans with increasing storage time. Cooked fresh faba beans also had a higher total RS content than cooked dried faba beans, although a greater increase in RS content was recorded in the latter upon storage. Starch retrogradation was more prominent in cooked dried faba beans than in cooked fresh faba beans, as indicated by the consistently higher FARS content. The α‐amylolysis rate decreased with increasing storage time, i.e. long‐stored (72 h) cooked faba beans exhibited slower starch digestion, and differences were recorded between fresh and dried beans. The predicted glycaemic index ranged between 60.9 and 58.0% for cooked fresh faba beans and between 57.9 and 55.8% for cooked dried faba beans, which is suggestive of slow glucose release from starch in faba beans. Copyright © 2007 Society of Chemical Industry     

马铃薯抗性淀粉结构特征及体外消化特性的研究

研究马铃薯抗性淀粉的结构特征与体外消化特性。方法 以马铃薯淀粉为对照, 采用红外光谱仪、XRD、DSC等手段研究了马铃薯抗性淀粉的碘吸收特性、颗粒形貌、晶型结构形态、热特性等。通过模拟体外消化评价了抗性淀粉的消化性能。结果 马铃薯淀粉和抗性淀粉碘吸收曲线最大吸收峰在580~600 nm,马铃薯抗性淀粉分子量分布更集中。马铃薯淀粉为B型结晶结构, 马铃薯抗性淀粉为C型结晶结构。SEM观察显示：马铃薯淀粉分子颗粒完整, 表面光滑, 整体呈不规则的椭圆形; 马铃薯抗性淀粉分子为不规则多面体, 分子表面粗糙、有凹陷, 且有少量的层状起伏; 红外光谱分析表明抗性淀粉未出现新的基团。DSC检测发现：马铃薯抗性淀粉的热稳定性更高; 马铃薯淀粉和抗性淀粉酶解前2 h内消化速率迅速增加, 酶解2 h后速率减慢, 消化速率逐渐趋于平缓, 血糖指数分别为70.42、40.50。结论 说明马铃薯抗性淀粉具有较致密的结晶结构和酶抗性, 抗消化性显著。     

出粉率对小麦粉理化特性及面条品质的影响

从制粉生产线上取82种系统粉,并根据灰分含量和流量配制出粉率为55％、60％、65％、70％、75％、80％、88％、95％、100％等9种不同小麦粉.对不同出粉率小麦粉理化特性及面条品质进行研究,结果表明:出粉率为55％～70％时,小麦粉来源于胚乳,小麦粉理化特性及面条品质较好,且各类指标在较小范围内浮动;出粉率为7...