Stability and antioxidant activity of phenolic compounds during in vitro digestion

The impact of phenolic compounds on the human body depended on the type, content, bioavailability, and antioxidant activity. After digestion, different phenolic compounds had different changes of bioavailability and antioxidant activity, which needed to be considered in the application. In this experiment, the structural stability and antioxidant activity of 27 phenolic compounds (phenolic acids, flavonols, flavonoids, and flavanones) were investigated during the in vitro simulated digestion. This experiment eliminated the influence of food matrix, provide a basis for regularity for the changes of phenolic substances in different materials. Results showed that the bioaccessibility of phenolic compounds with different structures varied, and there was a conformational relationship between the structure and stability. After oral digestion, most of the phenolic compounds underwent degradation and the cellular antioxidant activity (CAA) values decreased to a large extent (p < 0.05). After gastric digestion, the content (p > 0.05) and CAA values (p < 0.05) of most phenolic compounds increased. However, after intestinal digestion, the phenolic compounds were degraded to a greater extent, and different structures of phenolic compounds had different changes in CAA values (p < 0.05). In general, the CAA values of most phenolic compounds after in vitro digestion were lower than the initial value. The 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2′-azino-bis (3-ehylbenzthiazoline-6-sulfonic acid) (ABTS), and ferric reducing antioxidant power (FRAP) values of phenolic acids and flavonols decreased after in vitro simulated digestion (p < 0.05), while the values of DPPH, ABTS, and FRAP of most flavonoids (p < 0.05) increased. The increased oxygen radical absorption capacity (ORAC) values were found in most phenolic acids, flavonols, and flavonoids (p < 0.05), and most flavanones showed unremarkable changes in ORAC values (p > 0.05). In general, the changing trend of chemical-based antioxidant activity was consistent with the content of phenolic compounds.     

Interactions between proteins and phenolics: effects of food processing on the content and digestibility of phenolic compounds

Phenolic compounds have recently become one of the most interesting topics in different research areas, especially in food science and nutrition due to their health-promoting effects. Phenolic compounds are found together with macronutrients and micronutrients in foods and within several food systems. The coexistence of phenolics and other food components can lead to their interaction resulting in complex formation. This review article aims to cover the effects of thermal and non-thermal processing techniques on the protein–phenolic interaction especially focusing on the content and digestibility of phenolics by discussing recently published research articles. It is clear that the processing conditions and individual properties of phenolics and proteins are the most effective factors in the final content and intestinal fates of phenolic compounds. Besides, thermal and non-thermal treatments, such as high-pressure processing, pulsed electric field, cold plasma, ultrasonication, and fermentation may induce alterations  in those interactions. Still, new investigations are required for different food processing treatments by using a wide range of food products to enlighten new functional and healthier food product design, to provide the optimized processing conditions of foods for obtaining better quality, higher nutritional properties, and health benefits. © 2024 Society of Chemical Industry.     

外源物质在食品加工过程中的变化与安全性

许多农药、兽药、毒素、食品添加剂、重金属、环境污染物等外源物质不但本身有一定毒性, 污染食品后对人体造成危害, 而且在食品加工过程中也会发生变化而导致食品的二次污染, 可能分解为毒性更强的物质, 或与食品内源组分发生反应产生新的有害物质, 或与其他物质之间存在毒性协同增强作用等。实际上, 大量的外源物质在食品加工过程中的变化与安全性问题尚未研究。本文对该领域的研究进展进行了综述, 期望引起相关研究者的重视。     

菠萝浓缩汁带皮生产过程中多酚变化的研究

首先采用比色法测定了菠萝浓缩汁带皮榨汁生产过程中各工序下样品的褐变指数、总酚及原花青素的含量及变化情况,同时进一步用HPLC法确定了菠萝汁中单酚物质的种类和含量变化情况。研究表明,菠萝浓缩汁带皮加工过程中,总酚及原花青素含量与褐变指数是成正向相关的。     

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。     

Effects of germination time on phenolics,antioxidant capacity,in vitro phenolic bioaccessibility and starch digestibility in sorghum

The effects of germination time on phenolic, flavonoid, anthocyanin, antioxidant capacities, inhibition capacity of α-amylase, bioaccessibility of phenolic and digestibility of starch in sorghum were evaluated in this study. The levels of total phenolic, flavonoid and anthocyanin in germinated sorghum for 48 h increased by 39.74%, 37.28% and 52.21%, respectively. Germination also increased the composition of phenolic, flavonoid and anthocyanin in sorghum, and their antioxidant capacity and inhibitory rates of α-amylase. Additionally, in vitro digestion results showed that phenolic bioaccessibility increased by 10.18%, and digestibility of starch and expected glycaemic index (eGI) decreased by 13.87% and 5.26 in germinated sorghum for 48 h compared with the ungerminated sorghum. These results indicate that germination might be a green method to improve the nutritional quality of sorghum and promote the development of germinated whole-grain food.     

Phytochemical characteristics of citrus peel and effect of conventional and nonconventional processing on phenolic compounds: A review

Citrus peel is rich in functional ingredients such as essential oils (0.6–1%), fibers (6.30–42.13 g/100 g db), phenols (0.67–19.62 g/100 g db), and vitamin C (0.109–1.150 g/100 g db). Flavanones (hesperidin: 0.002–80.90 mg/g db, neohesperidin: 0.05–11.70 mg/g db, narirutin: 0.03–26.90 mg/g db; naringin: 0.08–14.40 mg/g db), and polymethoxylated flavones (sinensetin: 0.08–0.29 mg/g db, nobiletin: 0.20–14.05 mg/g db, tangeretin: 0.16–7.99 mg/g db) are the main phenolic compounds (PCs) of citrus peel. Due to their antioxidant activity, PCs are used in various applications such as formulation of healthy food, cosmetic, and pharmaceutical products. PCs present sensitivity to process operating conditions (during juice processing and further thermal and nonthermal processing). This review summarizes the main publications dealing with the proximate chemical composition, the functional properties, and the potential applications of the main citrus peel compounds. The effects of conventional and nonconventional processing on PCs of citrus fruits and their derived and coproducts are analyzed. The information provided in this review allows a better choice of appropriate processes and their optimal operating conditions for a better retention of antioxidants in citrus products.     

苹果品种和酿造工艺对苹果酒中酚类物质的影响研究

研究不同苹果品种及加工工艺与苹果酒中最终酚类物质的含量和种类的关系,了解不同苹果酒中酚类物质含量的差异.选用甘肃天水提供的两种不同工艺的6款苹果酒样,测定其中的总酚、酚酸及黄烷-3-醇的含量.苹果酒的总酚含量(以没食子酸计)较高,3种苹果酒中的主要酚类物质中,酚酸主要以原儿茶酸、绿原酸、p-香豆酸以及咖啡酸为主;黄烷-3-醇以儿茶素和表几茶素居多.结果表明,不同苹果品种之间酚类物质的含量及类别差异很大,相同品种的苹果酒中多酚的构成及含量会受到酿造工艺的影响.     

Effect of food processing on the resistant starch content of cereals and cereal products – a review

Depending on the conditions, processing of cereal grains may cause an increase or a decrease in the resistant starch (RS) content. This review discusses the impact of some of the processing techniques (cooking, tempering and extrusion) on the RS contents of cereals and cereal products. In addition to processing, the review briefly summarises the effects of lipids, dietary fibre and sugars, which may be present within the food matrix, on starch digestibility. The review also provides definitions for the four types of RS (RS type 1, 2, 3 and 4) and brief information about the beneficial effects of RS on human health.     

Bioavailability of phenolic compounds

Phenolic compounds in foods originate from one of the main classes of secondary metabolites in plants. They are essential for the growth and reproduction of plants, and are produced as a response for defending injured plants against pathogens. In recent years, there is a growing interest in phenolic compounds and their presumed role in the prevention of various degenerative diseases, such as cancer and cardiovascular diseases. The importance of antioxidant activities of phenolic compounds and their possible usage in processed foods as a natural antioxidant have reached a new high in recent years. The absorption and bioavailability of phenolics in humans are also controversial. Data on these aspects of phenolics are scarce and merely highlight the need for extensive investigations of the handling of phenolics by the gastrointestinal tract and their subsequent absorption and metabolism. In this article, absorption, metabolism, and the bioavailability of pheniolic compounds are reviewed.     

酚类化合物与食品大分子互作代谢研究进展

由于代谢形态变化以及其与食品大分子相互作用等因素的影响,酚类化合物的体内外生理活常常表现不一致。酚类化合物与脂质、蛋白质和碳水化合物等食品大分子的相互作用是造成这一现象的主要原因。本文综述了酚类化合物与食品大分子之间的相互作用及食品大分子对酚类化合物生物利用度和生理活性的影响,以期为深入探讨酚类化合物的体内代谢机制提供借鉴。      

Changes of phenolic compounds and antioxidant capacity in cocoa beans processing

A number of studies have shown that the consumption of cocoa and chocolate products has positive health effects on humans. The object of this research was to monitor changes of total and individual phenolics and antioxidant capacity during the cocoa bean manufacturing. The loss of cocoa phenolics and their antioxidant activity vary with the degree of technological process. The process of roasting and cocoa nib alkalisation had the major influence on phenolic compounds as well as on antioxidant capacity. The roasting treatment resulted in 14% loss of the total phenolics content, while alkalisation resulted in 64% loss of total phenolics content. Procyanidins B1 and B2 as well as (?)‐epigallocatechin were the unstable components, while caffeic acid derivate showed the greatest stability in all technological process. Furthermore, PCA showed that phenolic contents, antioxidant capacity and non‐fat cocoa solids parts of the samples were classified in groups according technological conditions.     

食品中酚类成分及其与其它成分相互作用研究进展

酚类成分是植物中种类最多的重要次生代谢产物,在植物源食品中有着广泛的分布。由于其优良的抗氧化活性、护色、增加风味及潜在保健功能等,成为了食品中重要的功能性成分和常用的食品添加剂。文章就食品中酚类成分及与其他成分如蛋白质、脂类、糖类、金属离子、维生素等的作用进行综述,以期为酚类成分的应用提供参考资料。     

Optimisation,characterisation and quantification of phenolic compounds in olive cake

The phenolic compounds in extracts from pressed olive cake were investigated. Free phenolic compounds were extracted from olive cake using methanol. To liberate bound phenolic compounds, the olive cake was subjected to basic and acidic hydrolysis followed by methanol extraction. The individual phenolic compounds and antioxidant activity of the extracts were determined. The highest total phenolic content and antioxidant activity were obtained using methanol extraction for 12 h at 70 °C. The RP-HPLC profiles for full-fat and defatted olive cake showed that protocatechuic acid, hydroxybenzoic acid, sinapic acid, p-coumaric acid, rutin and hesperidin were the predominant free phenolic compounds. Meanwhile, syringic acid, sinapic acid, caffeic acid and protocatechuic acid were the predominant bound phenolic acids. A positive correlation was observed between total phenolic content and antioxidant activity. The results indicated that most of the phenolic compounds in olive products were present in their free forms (75–90% of total phenolic content), while bound phenolic compounds were only a small proportion (10–25%) of total phenolic content.