Flavonoids are a large and diverse group of polyphenolic compounds with antioxidant effects, and onion (Allium cepa L.) is one of the richest sources of dietary flavonoids. Flavonoid content is affected by endogenous factors—genotype and agro-environmental conditions. Considerable research has been directed toward understanding the nature of polyphenols in different products and the factors influencing their accumulation. This review examines the impacts of pre- and postharvest factors on onions’ flavonoid content, highlighting how this knowledge may be used to modulate their composition and the potential use of onion by-products.
Part of the book: Flavonoids
The essential oils normally had low physicochemical stability and low solubility in water. These facts limit their industrial applications in general and in food formulations particularly. This chapter characterizes the physicochemical properties and the antioxidant and antimicrobial activities of three encapsulated essential oils – guava leaf, yarrow and black pepper essential oils – in hydroxypropyl-β-cyclodextrin (HPβCD).
Part of the book: Cyclodextrin
The kinetic behaviours in microemulsions can be easily modelled using an extension of the pseudophase model previously developed for micellar catalysis. This model considers that the microheterogeneous media can be considered as the sum of different conventional reaction media, where the reagents are distributed and in which the reaction can occur simultaneously. The reaction rate observed in the microheterogeneous system will be the sum of the velocities in each one of the pseudophases. This use can be considered as an extension of the pseudophase model, which has been developed for the quantitative analysis of nitrosation reactions in AOT/isooctane/water microemulsions and has been applied successfully in the literature in a large variety of chemical reactions.
Part of the book: Microemulsion
Recent research has substantially focused on residual subproducts containing chemical compounds with bioactive properties. Even though there are some culinary or medicinal uses of Capsicum seeds, there is still a seed mass waste from pepper processing. Many pepper leading producer countries generally lack the facilities and infrastructure required for such processing technologies and so, pepper seeds are usually either destroyed or employed as landfilling or as animal feed. This involves an inadvertent economic loss for producers as well as a detrimental environmental impact. However, there is a hidden potential within the pepper processing industry related to valorization of pepper seeds to obtain added value by-products and thus reduce generated waste. Pepper seeds are a good source of antioxidants, carotenoids, phenolic acids, flavonoids, and vitamins C, E, and A and are also rich in volatile compounds, among others. The unique alkaloids of this genus are capsaicinoids and capsainoids, which have been linked to many beneficial biochemical and pharmacological effects including anti-oxidative or anti-inflammatory activities. Other prominent bioactive compounds of peppers seeds include saponins, lectins, and polyunsaturated fatty acids. In this context, an overview of the biological properties, extraction systems, and possible industrial application of bioactive compounds of pepper whole fruit and seeds is presented.
Part of the book: Capsicum
Wine’s aroma is defined by volatile and non-volatile compounds that contribute to its make-up. The complex variety of volatile compounds, coming from grapes, interact with other non-volatile substances of the wine as precursors of wine’s aroma, known as primary aromas, which give the aroma of the young wine. The volatile compounds present in the skin and in the grape juice change according to the grape variety. Most of wine volatile compounds responsible for aroma are linked to sugars and they initially form odorless glycosides. Through the process of hydrolysis, they are reverted into an aromatic form. Chemical reactions among these compounds occur during the fermentation and in the first months of a wine’s existence, triggering fast and multiple modifications in wine’s aroma at this point. As wine ages and matures, changes and development in aroma will continue to take place but at a slower and more gradual pace. The study of the compounds responsible for aroma and flavor, as well as their correlation with the wine quality, is ongoing. Improving the knowledge of wine aromatic compounds could increase the risk of its potential adulteration; however, consumers prefer wine for its natural origin, so this scenario is unlikely in the future.
Part of the book: Chemistry and Biochemistry of Winemaking, Wine Stabilization and Aging
During the last decades, consumers have increased the demand for healthier natural foods with lower presence of chemical additives. One reason of this choice is the controversy about chemical additives possible adverse effects. To fulfill market needs, different techniques have been developed to extract compounds from various raw materials to produce natural additives with different properties (preservatives, emulsifiers, or colorants) and bioactivities. In addition, the growing concern about the effects of climate change has led the development of more sustainable techniques to carry out the extraction. The use of new alternative nonconventional, emerging, or green extraction methodologies has gained considerable attention during the last decade. These novel techniques have been applied to minimize any negative changes in the nutritional, physicochemical or sensory properties of the natural source, while at the same time reducing the environmental impact of the process and gaining competitiveness of the world market. For this purpose, new green extraction methods have been proposed and optimized for the reduction of the consumption of raw materials, solvents, and energy. In this chapter, a revision of different types of green extraction techniques is compiled together with the main factor that can affect extraction-process feasibility and the main challenges and future trends for their development.
Part of the book: Natural Food Additives
The application of natural colorants is increasing in the food industry because they are considered safer and healthier than some synthetic pigments. Natural colorants can improve the organoleptic properties of foodstuffs, provide additional benefits such as enhance their nutritional value and/or extend shelf-life. Plants, fungi, bacteria or algae naturally produce different natural colorants, including carotenoids. These compounds are classified into two main groups: pure hydrocarbon carotenes (α- and β-carotenes, lycopene) and oxygenated derivatives of xanthophylls (lutein, zeaxanthin, astaxanthin, fucoxanthin, cryptoxanthin, etc.). Carotenoids have been related with beneficial properties like antioxidant, antidiabetic, antitumor or antimicrobial, so they are a natural and healthy alternative to the use of synthetic colorants. Thus, it is critical to optimize their extraction, by utilizing novel and green techniques, and their stability through encapsulation processes. This chapter aims to review natural sources of carotenoids, strategies to efficiently extract and produce them and their potential application as food colorants.
Part of the book: Natural Food Additives
Recently, there has been an increasing interest in health-promoting products which are also natural and safe for consumption because the consumer market has been searching for a healthy lifestyle. This global market trend has driven the food industry to invest in developing innovative products containing bioactive components. Flavonoids are a group of phenolic compounds of low molecular weight, consisting of 15 carbon atoms. Their alterations in the heterocyclic ring’s substitution pattern generate six subclasses: flavonols, flavanols, flavones, flavanones, isoflavones and anthocyanins. Also, different studies have reported that diets rich in flavonoids provide numerous benefits associated with health-promoting effects by reducing the risk of development of chronic diseases such as cardiovascular diseases, diabetes type II and some types of cancers. These effects have been related to their biological properties which also include other activities such as colorant effects (e.g., anthocyanins), transforming them into potential food additives with desirable capacities. Therefore, this review aims to revise the classes of flavonoids and their main biological properties as well as the most used extraction techniques applied for obtaining these compounds, their bioavailability and the application to formulate new natural food additives.
Part of the book: Natural Food Additives