Changes in mineral absorption inhibitors consequent to fermentation of Ethiopian injera: implications for predicted iron bioavailability and bioaccessibility

Possible changes in mineral bioavailability during processing of different types of injera sampled in Ethiopian households were assessed using different methods: phytic acid/mineral molar ratio, absorption prediction algorithm and in vitro availability measurements. Most foods analysed were rich in iron, but most of the iron likely resulted from soil contamination. The highest iron, zinc and calcium contents were found in teff–white sorghum (TwS) injera and flour. The lowest phytic acid/Fe and phytic acid/Zn molar ratios were found in barley–wheat (BW) and wheat–red sorghum (WrS) injeras. Although ideal phytic acid/Fe molar ratios (<0.4) were found in BW and WrS injeras, no significant difference between in vitro iron bioaccessibility and algorithm predicted absorption was observed. In injera, phytic acid degradation alone is unlikely to improve iron bioavailability, suggesting interactions with other absorption inhibitors. The use of phytic acid/Fe molar ratios to predict bioavailability may thus be less appropriate for iron‐contaminated foods.     

In vitro bioavailability of calcium and iron from selected green leafy vegetables

The objective of the present investigation was to analyze the relative influence of oxalic acid, phytic acid, tannin and dietary fiber on in vitro availability of iron and calcium from green leafy vegetables (GLV). Thirteen GLV were selected and analyzed for iron, calcium, oxalic acid, phytic acid, tannin and dietary fiber contents using standard methods. The bioavailability of calcium and iron in the GLV was estimated by equilibrium dialysis. Oxalic acid content was less than 1 g kg^?1 in four greens and ranged between 1.22 to 11.98 g kg^?1 in the remaining. Dietary fiber ranged from 19.5 to 113.7 g kg^?1. Tannin content ranged between 0.6138 and 2.1159 g kg^?1 with the exception of two GLV that had 0.1332 and 14.8619 g kg^?1. Four GLV were found to have approximately 40% bioavailable iron, while the others were in the range of 6–30%. In vitro available calcium was less than or equal to 25% in eight GLV and between 34% and 52% in five GLV. Multiple regression analysis revealed that these factors together accounted for 53% (r² = 0.53) and 45% (r² = 0.45) inhibition of iron and calcium absorption, respectively. These findings infer that calcium and iron availability is influenced by the constituents present in the GLV. Copyright © 2006 Society of Chemical Industry     

Effects of dietary fiber and phytic acid on mineral availability.

In general, it has been shown that dietary fiber may bind metallic cations in both in vitro and in vivo studies. However, there clearly are many unresolved questions on the effects of high-fiber diets on mineral availability. On one side, the effects of fiber on the utilization of nutrients vary greatly with the amount and type of fiber. In addition, there are many agents in both food and the digestive tract that may affect the mineral binding to fiber: some agents may inhibit binding, while others will enhance it. Also, there are several major difficulties in drawing conclusions from the in vitro and in vivo studies due to the different experimental conditions, methods used to follow the mineral balance, etc. Finally, it must be borne in mind that fiber and phytic acid occur together in fiber-rich diets and, thus, it is difficult to separate the effects of fiber and phytate in the utilization of most essential polyvalent metallic ions. The studies summarized in this review show that the recommendation for increasing dietary fiber in Western communities would not be expected to have any adverse effect on mineral absorption if we increase not only the intake of fiber, but also the dietary intake of other food components such as protein (both vegetable and animal protein) and ascorbic, citric, and oxalic acids (in fruits and vegetables). The adequate intake of minerals, fat, and simple sugars are maintained with this type of diet. The recommendations should be best interpreted in such a way as to prevent the consumption of excessive amounts of phytate, particularly for those whose mineral needs are great. Further studies are still needed in this field in order to understand the conflicting results published in the literature regarding the effects of fiber on the utilization of minerals; however, the studies reviewed in this article may give us an idea of the complexity of mineral availability in fiber-rich, phytate-rich diets.     

The role of dietary fiber in the bioaccessibility and bioavailability of fruit and vegetable antioxidants

Antioxidants are abundant compounds primarily found in fresh fruits and vegetables, and evidence for their role in the prevention of degenerative diseases is continuously emerging. However, the bioaccessibility and bioavailability of each compound differs greatly, and the most abundant antioxidants in ingested fruit are not necessarily those leading to the highest concentrations of active metabolites in target tissues. Fruit antioxidants are commonly mixed with different macromolecules such as carbohydrates, lipids, and proteins to form a food matrix. In fruits and vegetables, carbohydrates are the major compounds found, mainly in free and conjugated forms. Dietary fiber, the indigestible cell wall component of plant material, is considered to play an important role in human diet and health. Most studies on antioxidant bioavailability are focused on foods and beverages from which antioxidants are easily released. There is evidence indicating that food microstructure affects the bioaccessibility and bioavailability of several nutrients, referring mostly to antioxidants. Nevertheless, the specific role of dietary fiber in the absorption of antioxidants has not been widely discussed. In this context, the purpose of the present review is to compile and analyze evidence relating to the association between dietary fiber and antioxidants, and the physical and chemical interactions that modulate their release from the chyme in the gastrointestinal tract.     

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。     

Phytic acid and its interactions: Contributions to protein functionality,food processing,and safety

Is phytic acid (IP6) an undesirable constituent for vegetables and foods? This question is getting harder to answer. Phytic acid contributes to mineral/protein deficiency, but also brings about potential physiological benefits. Both the positive and negative effects boil down to the interactions among IP6, metal ions, and biopolymers. In the wake of the booming market of plant-based foods, an unbiased understanding of these interactions and their impacts on the foods themselves is a necessity to the smart control and utilization of plant-sourced phytates. This overview presents updated knowledge of IP6-related interactions, with a strong focus on their contributions to food functionality, processability, and safety.     

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。     

A review of the impact of processing on nutrient bioaccessibility and digestion of almonds

Almond kernels contain phytochemicals and nutrients that potentially have positive health benefits in relation to heart disease, diabetes and obesity. One important mechanism associated with these benefits is an imposed limit on bioaccessibility (release) of nutrients, such as lipids, from almond tissue during mastication and digestion. Recent studies have demonstrated the importance of food structure during the digestion of plant foods. In particular, in the almond kernel, depending on its structure and degree of processing, the amount of lipid released from the almond tissue matrix and the fatty acids produced from lipolysis has been found to vary substantially. This review aims at discussing the commercial methods of almond processing and the different almond forms produced for human consumption, mainly with respect to their impact on nutrient composition, digestion and metabolism.     

Food processing,gut microbiota and the globesity problem

Abstract

In the context of diseases of affluence, western diets have in the past years mainly been studied on their fat and sugar content and lack of dietary fiber. Yet, the more general aspect of food processing has recently sparked scientific interest as well. In addition, the gut microbiota have been put forward as an important link between diet, obesity and non-communicable diseases (NCD). Western dietary patterns, containing large amounts of processed foods might create an imbalance in the gut system by affecting gut bacteria and their metabolism. Here we discuss what has been already published regarding the relationship between several recently researched features of processed foods and the etiology of obesity and NCD. The addressed features concern micronutrient and energy density, several types of food additives and the generation of advanced glycation end products by thermal treatment during food processing. Overall, literature indicates that all discussed aspects can be linked to western ailments and that they can have a potential negative impact on human microbiota. Therefore, we propose that the thesis that a distressed gut microbiota is a mechanism that might explain how food processing features could harm human health is gaining empirical evidence. Future research will need to address the question whether the alteration of the gut microbiota is a direct or an indirect (via the host) effect. These conclusions are important assets in the fight against the continuing worldwide upsurge of obesity and NCD.     

超声波辅助提取水酶法豆渣中植酸的工艺优化

以水酶法提油后的副产物豆渣为原料,探索超声波辅助技术提取植酸的工艺条件,并与振荡浸提法对比。首先选取超声功率、超声温度、超声时间进行单因素实验,通过正交实验选出最佳的超声参数。然后在最优超声参数的基础上,以植酸得率为响应值,利用Box-Behnken中心组合设计原理和响应面分析法,确定提取植酸的最佳条件。结果表明,超声提取植酸的条件为:超声温度50℃,超声功率500 W,超声时间20 min;醋酸浓度4.1%、料液比1∶17 g/m L、提取温度64℃、提取时间33 min。在以上条件下,平均植酸得率为1.23%,与振荡提取法相比,提高41.3%。      

Modulation of the human gut microbiota by phenolics and phenolic fiber‐rich foods

The gut microbiota plays a prominent role in human health. Alterations in the gut microbiota are linked to the development of chronic diseases such as obesity, inflammatory bowel disease, metabolic syndrome, and certain cancers. We know that diet plays an important role to initiate, shape, and modulate the gut microbiota. Long‐term dietary patterns are shown to be closely related with the gut microbiota enterotypes, specifically long‐term consumption of carbohydrates (related to Prevotella abundance) or a diet rich in protein and animal fats (correlated to Bacteroides). Short‐term consumption of solely animal‐ or plant‐based diets have rapid and reproducible modulatory effects on the human gut microbiota. These alterations in microbiota profile by dietary alterations can be due to impact of different dietary macronutrients, carbohydrates, protein, and fat, which have diverse modulatory effects on gut microbial composition. Food‐derived phenolics, which encompass structural variants of flavonoids, hydroxybenzoic acids, hydroxycinnamic acids, coumarins, stilbenes, ellagitannins, and lignans can modify the gut microbiota. Gut microbes have been shown to act on dietary fibers and phenolics to produce functional metabolites that contribute to gut health. Here, we discuss recent studies on the impacts of phenolics and phenolic fiber‐rich foods on the human gut microbiota and provide an insight into potential synergistic roles between their bacterial metabolic products in the regulation of the intestinal microbiota.     

Role of polysaccharides in food,digestion, and health

Polysaccharides derived from plant foods are major components of the human diet, with limited contributions of related components from fungal and algal sources. In particular, starch and other storage carbohydrates are the major sources of energy in all diets, while cell wall polysaccharides are the major components of dietary fiber. We review the role of these components in the human diet, including their structure and distribution, their modification during food processing and effects on functional properties, their behavior in the gastrointestinal tract, and their contribution to healthy diets.     

Berry fruits-enriched pasta: effect of processing and in vitro digestion on phenolics and its antioxidant activity,bioaccessibility and potential bioavailability

Pasta samples were made by substituting wheat flour (2.5% and 7.5%) for lyophilised raspberry, boysenberry, and redcurrant and blackcurrant. Total polyphenol content showed minimum variation during processing while anthocyanins presented high degradation. In general, the first minutes of cooking showed the major detrimental effect on antioxidant activity. In vitro starch hydrolysis showed the lowest value with the addition of raspberries and boysenberries. During simulated digestion, polyphenols were released from pasta matrix reaching a 2.3- to 4.3-fold increase in bioaccessible polyphenols. Likewise, values observed for reducing power and free radical scavenging activity ranged from a 0.7- to 2.0-fold and 1.6- to 6.8-fold increase in relation to cooked pasta, respectively. In addition, ≈40% of dialysability was observed for scavenging activity. In conclusion, enrichment of pasta with fine fruits is an effective tool to obtain a product with enhanced antioxidant potential.     

植酸酶在食品和医药方面的应用展望

从植酸及其盐类的抗营养作用出发，简单介绍了植酸酶的分类，来源，着重阐述了植酸酶在食品和医药方面应用及所面临的困难和应用前景。     

植酸的食品保鲜机理及应用

本文通过植酸的分子结构,分析了植酸的理化特性及高效螯合金属离子的作用机理。介绍了植酸在食品行业中作为抗氧化剂、护色剂、沉淀剂的理论研究和应用概况,并对植酸食品保鲜技术进行了展望。     

物理加工方法对淀粉及淀粉基食品中抗性淀粉含量的影响

抗性淀粉是一种低热量的功能性食品成分,具有促进肠道健康、降低餐后血糖等保健作用,但常因在摄入食品中含量过低而难以发挥功效。为了促进抗性淀粉在食品工业中的实际应用,已有研究者尝试利用物理、化学、酶处理等加工方法提高淀粉及淀粉基食品中的抗性淀粉含量,其中物理方法最为常见,其提高效果显著、安全性高,还可以改善抗性淀粉的物理性质,有利于拓展抗性淀粉在食品工业中的应用。因此,本文综述了不同物理加工方法对淀粉及淀粉基食品中抗性淀粉含量的影响规律,并对比分析这些加工方法对该含量的提高效果,以期为提高食品中抗性淀粉含量提供高效的方法选择参考。     

挤压膨化对牛蒡膳食纤维提取及加工特性影响的研究

采用微波膨化、挤压膨化对牛蒡膳食纤维提取的工艺及加工特性进行研究。以膨化率作为评定指标,研究挤压膨化中原料含水量、机筒温度、螺杆转速及喂料速度的影响,以及微波膨化、挤压膨化处理后牛蒡膳食纤维的持水力、持油力、膨胀力及阳离子交换能力等加工特性的变化。结果表明,微波膨化、挤压膨化均能提高牛蒡中可溶性膳食纤维含量,很好地改善牛蒡中膳食纤维的持水力、持油力、膨胀力和阳离子交换能力等加工特性。当物料含水量15%、机筒温度150℃、螺杆转速250r/min、喂料速度300r/min时,挤压膨化效果最好,膨化率达到1.65%,可溶性膳食纤维达30.65%,比对照提高27.25%。      

Hornification: Lessons learned from the wood industry for attenuating this phenomenon in plant-based dietary fibers from food wastes

A significant amount of waste is annually generated worldwide by the supply chain of the food industry. Considering the population growth, the environmental concerns, and the economic opportunities, waste recovery is a promising solution to produce valuable and innovative ingredients for food and nonfood industries. Indeed, plant-based wastes are rich in dietary fibers (DF), which have relevant technical functionalities such as water/oil holding capacity, swelling capacity, viscosity, texture, and physiological properties such as antioxidant activity, cholesterol, and glucose adsorption capacities. Different drying technologies could be applied to extend the shelf life of fresh DF. However, inappropriate drying technologies or process conditions could adversely affect the functionalities of DF via the hornification phenomenon. Hornification is related to the formation of irreversible hydrogen bindings, van der Waals interactions, and covalent lactone bridges between cellulose fibrils during drying. This review aims to capitalize on the knowledge developed in the wood industry to tackle the hornification phenomenon occurring in the food industry. The mechanisms and the parameters affecting hornification as well as the mitigation strategies used in the wood industry that could be successfully applied to foods are summarized. The application of conventional drying technologies such as air or spray-drying increased the occurrence of hornification. In contrast, solvent exchange, supercritical drying, freeze-drying, and spray-freeze-drying approaches were considered effective strategies to limit the consequences of this phenomenon. In addition, incorporating capping agents before drying attenuated the hornification. The knowledge summarized in this review can be used as a basis for process design in the valorization of plant-based wastes and the production of functional DF that present relevant features for the food and packaging industries.     

曲酸的发酵法生产及其在食品加工中的应用

概述了曲酸发酵法生产的菌种选育、发酵法工艺、提取及精制及其在食品加工中的应用。