Technologies for enhancement of bioactive components and potential health benefits of cereal and cereal-based foods: Research advances and application challenges

Cereal grains are a major source of human food and their production has steadily been increased during the last several decades to meet the demand of our increasing world population. The modernized society and the expansion of the cereal food industry created a need for highly efficient processing technologies, especially flour production. Earlier scientific research efforts have led to the invention of the modern steel roller mill, and the refined flour of wheat has become a basic component in most of cereal-based foods such as breads and pastries because of the unique functionality of wheat protein. On the other hand, epidemiological studies have found that consumption of whole cereal grains was health beneficial. The health benefit of whole cereal grain is attributed to the combined effects of micronutrients, phytochemicals, and dietary fibre, which are mainly located in the outer bran layer and the germ. However, the removal of bran and germ from cereal grains during polishing and milling results in refined flour and food products with lower bioactive compounds and dietary fibre contents than those from whole grain. Also, the level of bioactive compounds in cereal food is influenced by other food preparation procedures such as baking, cooking, extrusion, and puffing. Therefore, food scientists and nutritionists are searching for strategies and processing technologies to enhance the content and bioavailability of nutrients, bioactive compounds, and dietary fibre of cereal foods. The objective of this article was to review the research advances on technologies for the enhancement of bioactive compounds and dietary fibre contents of cereal and cereal-based foods. Bioactivities or biological effects of enhanced cereal and cereal-based foods are presented. Challenges facing the application of the proposed technologies in the food industry are also discussed.     

Comparison of in vitro starch digestibility methods for predicting the glycaemic index of grain foods

BACKGROUND: In vitro starch digestibility tests are useful for the prediction of glycaemic index (GI). However, there are no internationally recognised methods and no one method has been found to be suitable for all food types. This study compared six in vitro methods, using four grain foods, including those with a varied particle size and soluble fibre content. Method variations included using chewing or mincing, mincing with or without amylase and incubation in a restricted versus non‐restricted system. Hydrolysis index (HI) values, calculated from the starch digestibility curves and GI prediction equations were used to compare the in vitro results to GI. RESULTS: HI values for five of the six methods ranked all foods in the same order as the GI values. Using a GI prediction equation (predicted GI_HI) the mincing (without amylase) non‐restricted method had the smallest standard error of prediction between the predicted GI_HI and GI values. This method was then validated using 14 grain foods and demonstrated a significant correlation (r = 0.93, P < 0.01) between the in vitro starch digestibility and reported GI responses. CONCLUSIONS: The non‐restricted mincing method showed good potential as a new in vitro starch digestibility method for predicting GI in grain foods. Copyright © 2007 Society of Chemical Industry     

湿热处理法制备慢消化淀粉及其性质研究

以蜡质玉米淀粉为原料,采用湿热处理法制备慢消化淀粉,并研究了其性质。研究出湿热处理制备慢消化淀粉的优化工艺为:淀粉体系的水分含量35%(w/w),温度120℃,时间为10h,慢消化淀粉含量达9.25%。扫描电镜照片显示,湿热处理后淀粉颗粒表面出现了裂纹和凹坑,淀粉糊化温度升高,峰值粘度降低。     

大力发展杂粮产业和全谷物食品推进粮食供给侧结构性改革

发展优质杂粮产业是我国在"十三五"乃至更长时期粮食供给侧结构性改革的重要举措之一,可为大力发展"全谷物健康食品"提供优质原料。发展全谷物食品产业是我国粮食行业落实中央建设"健康中国"伟大发展战略的重要组成部分,"全谷物食品"已是全球粮食加工和食品工业的发展方向,它的意义不仅在于促进国民健康,同时具有保证粮食安全、资源节约利用和环境保护等多方面的战略意义。论述了当前我国以杂粮、杂豆为主体的全谷物食品的发展势态,我国许多食品企业和大专院校、研究院所对全谷物食品进行大量研究和开发,在不断创新的基础上取得了良好业绩和许多宝贵经验,对解决粮食供给侧结构性改革,增加粮食生产效益,增加农民收入,确保粮食安全具有重大意义。     

蒸汽爆破技术在全谷物食品加工中的应用

蒸汽爆破技术是一种安全高效的纤维预处理技术,主要应用于木质纤维素原料的预处理。近年来作为一种新兴的麸皮预处理技术在全谷物加工领域得到关注,该技术对谷物膳食纤维改性和功能性成分提取取得显著的进展。本文综述了蒸汽爆破技术的工作原理以及在全谷物加工当中的研究进展,重点介绍其在降低麸皮的颗粒度、增加膳食纤维的溶解性、提高酚酸和游离氨基酸含量、钝化内源酶等方面的影响,以及蒸汽爆破后麸皮的微观结构和分子结构的变化,进一步分析了其在全谷物食品加工领域的应用前景,并对其在全谷物领域中的发展进行总结和展望。     

Health benefits of whole grain: effects on dietary carbohydrate quality,the gut microbiome,and consequences of processing

Grains are important sources of carbohydrates in global dietary patterns. The majority of these carbohydrates, especially in refined-grain products, are digestible. Most carbohydrate digestion takes place in the small intestine where monosaccharides (predominantly glucose) are absorbed, delivering energy to the body. However, a considerable part of the carbohydrates, especially in whole grains, is indigestible dietary fibers. These impact gut motility and transit and are useful substrates for the gut microbiota affecting its composition and quality. For the most part, the profile of digestible and indigestible carbohydrates and their complexity determine the nutritional quality of carbohydrates. Whole grains are more complex than refined grains and are promoted as part of a healthy and sustainable diet mainly because the contribution of indigestible carbohydrates, and their co-passenger nutrients, is significantly higher. Higher consumption of whole grain is recommended because it is associated with lower incidence of, and mortality from, CVD, type 2 diabetes, and some cancers. This may be due in part to effects on the gut microbiota. Although processing of cereals during milling and food manufacturing is necessary to make them edible, it also offers the opportunity to still further improve the nutritional quality of whole-grain flours and foods made from them. Changing the composition and availability of grain carbohydrates and phytochemicals during processing may positively affect the gut microbiota and improve health.     

抗性、慢消化淀粉的制备及其控血糖机理的研究进展

抗性淀粉（RS）与慢消化淀粉（SDS）因其良好的抗消化性和功能特性得到了广泛关注,研究已证实其在调控血糖方面具有显著效果,成为近年来兴起的新型功能性食品原料。本文介绍了RS与SDS在物理、化学、生物方面主要制备方法及其形成机制,对RS与SDS在不同动物模型体内可能存在的血糖调控机理进行了整合,例举了它们在功能性食品中的应用,并对现存的问题作了展望,为未来RS与SDS的研究与应用提供参考。     

Properties of extruded whole grain cereals and pseudocereals flours

Common cereals such as wheat are widely used worldwide in extruded products. Nevertheless, other locally available grains would be beneficial for local consumers regarding taste preference, nutritional needs and sustainability. Locally available cereals, that is millet, teff, sorghum and pseudocereals, that is quinoa and amaranth flours were extruded at the same processing conditions, and the resulting properties were compared to those of extruded refined wheat flour. Amaranth flour contained the highest protein content (16%). Sorghum was the highest in calories because of its high lipid content (10%). The extrusion process greatly increased a water solubility index (WSI) of amaranth from 11% to 61%, while the WSI level of quinoa was almost not affected (WSI of 4%). The expansion properties varied differently among grain types. These grains had a sectional expansion index (SEI) ranging between 11 and 13, which could not achieve the performance of the refined wheat (SEI of 22). The lowest expansion was observed for amaranth flour which contained the lowest starch content. Sorghum extrudates, interestingly, provided comparable stress at rupture value to that of wheat. For the mechanical properties, none of these local grains could fully replace refined wheat at the employed extrusion conditions.     

菰米的营养组分及其健康功效

从菰米的营养组分、健康功效、活性机制和未来的研究重点等方面概述了近年来国内外关于菰米的研究进展,并对菰米的进一步研究开发与综合利用进行了展望。     

Effect of baking on nutritional properties of starch in organic spelt whole grain products

Consumers of organic spelt food products claim health benefits or sense of well-being from their consumption as opposed to consumption of common wheat products. This study was designed to help clarify the validity of such claims through the evaluation of nutritional properties of starch in a variety of organic spelt products, including breads, biscuits, cookies and muffins, in comparison with their respective common wheat products. Three fermented bread products, namely, yeast leavened, sour and yeast/sour dough were evaluated. Rate and extent of starch digestion were based on the measurement of starch digestion index (SDI) and rapidly available glucose (RAG). The commercial spelt variety used contained approximately eight to ten fold the amount of resistant starch (RS) as compared to common wheat, averaging 3.7% versus 0.4%, and exhibited lower SDI and RAG values. This is the first report to demonstrate high content of RS in spelt. After mixing and fermentation, RS, SDI and RAG reduced, but were still higher in spelt doughs and batters than in those of common wheat. After baking, slight differences were observed in rate and extent of starch digestion between spelt and common wheat baked products. The study showed that differences among baked products were more pronounced than those between spelt and common wheat products.     

Functional foods: a survey of health claims, pros and cons, and current legislation

Functional foods stand for a new category of remarkably promising foods bearing properties (i.e., low cholesterol, antioxidant, anti-aging, anticancer, etc.) that have already rendered them quite appealing. There are many classes offunctionalfoods (pro- and pre-biotics, dietary fiber, low fat, etc.), and their definition is occasionally confused with that of nutraceuticals and novel foods. Consumers' main skepticism regarding functional foods resides in the veracity of health claims and in the low and often inadequate control of their claimed properties. Legislation concerning this matter is progressing at an extremely low pace and currently only Japan, the U.K., U.S.A., and Scandinavian countries have managed to make notable progress. Moreover, the labeling of functional foods is far from informative, providing scanty information about nutritional value, storage, and cooking recipes. It is anticipated that technological advances in the food industry, in conjunction with extensive clinical trials and governmental control, will eventually guarantee the credibility of health claims and ensure consumers' confidence in functional foods.     

Whole grains — impact of consuming whole grains on physiological effects of dietary fiber and starch

Much of the present research on the physiological effects of dietary fiber and starch has been done on sources isolated from the parent material, and it is not clear whether they have the same effects if fed in the intact or whole grain. For dietary fiber, physiological effect depends on extent of fermentation in the large intestine, and this is influenced by chemical composition, solubility, physical form, and presence of lignin or other compounds. All of these factors are altered by isolation of a fiber source from the whole grain, and hence effects of eating fiber vary. Similarly, physical form and presence in the whole grain will affect digestibility of starch in the small intestine, which in turn influences the glycemic response and colonic effects determined by the extent of malabsorption and entry into the colon. Starch that enters the colon is fermented and produces short‐chain fatty acids, particularly butyrate, which is necessary to maintain a healthy mucosa. Hence, their presence within the whole grain may have important implications for health for both dietary fiber and starch. Evidence indicates that such effects are beneficial and that whole‐grain consumption should be encouraged.     

全谷物调节代谢性疾病机制研究的新视角——肠道微生物

全谷物中含有丰富的植物化学素和多种营养成分,增加全谷物的摄入能够显著降低代谢性疾病(如肥胖、Ⅱ型糖尿病)的发生率,然而也正是由于全谷物成分复杂,很多现有的体外研究模型和方法并不适用于全谷物保健机制的研究。随着肠道微生物与人体健康之间的关系逐步得到揭示,肠道微生物启发了全谷物健康保健机制的研究方向。本文将详细介绍肠道微生物与代谢性疾病、全谷物成分与肠道微生物以及全谷物与肠道微生物之间的研究现状,并分析以肠道微生物作为全谷物保健机制研究靶点的可行性,目的在于为明确健康作用的全谷物及其相关产品的综合开发提供研究思路,使得来源广泛、食用方便、功效显著的全谷物更好地服务于人类健康。      

Whole grain rice: Updated understanding of starch digestibility and the regulation of glucose and lipid metabolism

Nowadays, resulting from disordered glucose and lipid metabolism, metabolic diseases (e.g., hyperglycemia, type 2 diabetes, and obesity) are among the most serious health issues facing humans worldwide. Increasing evidence has confirmed that dietary intervention (with healthy foods) is effective at regulating the metabolic syndrome. Whole grain rice (WGR) rich in dietary fiber and many bioactive compounds (e.g., γ-amino butyric acid, γ-oryzanol, and polyphenols) can not only inhibit starch digestion and prevent rapid increase in the blood glucose level, but also reduce oxidative stress and damage to the liver, thereby regulating glucose and lipid metabolism. The rate of starch digestion is directly related to the blood glucose level in the organism after WGR intake. Therefore, the effects of different factors (e.g., additives, cooking, germination, and physical treatments) on WGR starch digestibility are examined in this review. In addition, the mechanisms from human and animal experiments regarding the correlation between the intake of WGR or its products and the lowered blood glucose and lipid levels and the reduced incidence of diabetes and obesity are discussed. Moreover, information on developing WGR products with the health benefits is provided.     

Antioxidants and hormone‐mediated health benefits of whole grains

Lignans and phytoestrogens have been associated with protective effect against hormone‐related diseases, for example, cancer of the breast and prostate, and potential mechanisms for this effect have been reported. Antioxidants also appear to have some protective effect against diseases associated with reactive free radicals such as coronary heart disease and cancer. Whole grains contain some of these substances particularly the mammalian lignan precursors, vitamin E, other phenolic compounds, Se, and phytic acid. These substances may in part be responsible for the reduced risk of cancer and coronary heart disease associated with intake of high‐fiber diets containing whole grains. Because they are more associated with the fiber in the outer layers of the grain, the intake of whole vs. refined grain is emphasized for optimum health benefits.     

肉制品辅料对木薯淀粉糊化黏度的影响

木薯淀粉可作为肉制品中的黏结剂，对改善肉制品的组织结构有重要作用。通过对木薯淀粉糊化黏度的测定，以及脂肪、食盐、葡萄糖、大豆分离蛋白等肉制品中主要营养成分对木薯淀粉糊化黏度的影响研究，为木薯淀粉在肉制品中的应用提供理论基础。     

稻谷整粒与粉碎水分测试方法的对比分析

通过连续测试在一定含水量区间内的稻谷籽粒含水量,对比分析国家标准稻谷粉碎测试与国外稻谷整粒测试所得的含水量。结果表明,稻谷经粉碎后测试含水量与整粒测试含水量在整个水分测试区间存在较大差异,整粒测试所得含水量大于粉碎测试所得含水量,并且随着稻谷籽粒含水量的降低2种测试方法间含水量差异性逐渐减小,直至稻谷含水量达到11%左右时2种测试方法间无差异。因此总体来说整粒测试方法所得稻谷含水量测定结果更准确可靠。     

低碳水化合物饮食和低脂肪饮食对2型糖尿病患者体质量及血糖的影响

碳水化合物与慢性病的关系密切,研究日益增多,然而对碳水化合物质量的描述尚未有明确的定义。目前常用的指标包括膳食纤维含量、全谷物摄入量、游离糖摄入量、血糖生成指数（Glycemic index,GI）这四个方面。高质量的碳水化合物食物一般具有高膳食纤维、全谷物食物高摄入量、低游离糖、低GI的特性,其中GI与人体血糖应答直接相关,是描述碳水化合物质量的重要指标。本文从消化吸收、加工方式、淀粉的组成和结构等三个方面总结了影响GI的因素,并对不同食物来源的GI进行了分析。消化吸收速度、不同加工方式都可影响GI,而淀粉的组成和结构对GI也有直接影响。直链淀粉和支链淀粉的结构组成不同,相比于直链淀粉,支链淀粉具有更多的淀粉酶结合位点,从而有更高的消化速率。因此直链淀粉含量高的食物,GI值相对低。根据淀粉中所含支链淀粉晶型可以将淀粉分为A型、B型、C型,3种类型的淀粉中,A型最容易消化,B型和C型不易消化,具有低GI特性。淀粉微观结构的研究将有助于深入了解GI的影响因素和为食物碳水化合物质量的评价补充一个新的角度。     

多酚-膳食纤维相互作用及其影响多酚生物利用率研究进展

多酚广泛存在于植物源食品中,具有潜在的促进人体健康作用。天然多酚绝大多数以结合态存在,并且多酚与膳食纤维结合的比例要显著高于其他基质。多酚和膳食纤维的相互作用在食品加工和机体消化等环节会受到不同因素的影响,从而发生复杂的变化。近年来,多酚-膳食纤维相互作用对多酚生物利用率的影响已经受到了越来越多的关注。本文首先分析了多酚与膳食纤维的不同结合方式,随后总结了影响多酚与膳食纤维相互作用的主要因素,最后探讨了两者相互作用对于多酚生物利用率的影响,可为改善多酚食品的营养健康品质以及提高多酚的生物利用率提供一定的理论参考。