Metabolism of carotenoids and apocarotenoids during ripening of raspberry fruit.

Carotenoids are important lipophilic antioxidants in fruits. Apocarotenoids such as alpha-ionone and beta-ionone, which are breakdown products of carotenoids, are important for the flavor characteristics of raspberry fruit, and have also been suggested to have beneficial effects on human health. Raspberry is one of the few fruits where fruit ripening is accompanied by the massive production of apocarotenoids. In this paper, changes in levels of carotenoids and apocarotenoids during raspberry fruit ripening are described. In addition, the isolation and characterization of a gene encoding a carotenoid cleavage dioxygenase (CCD), which putatively mediates the degradation of carotenoids to apocarotenoids during raspberry fruit ripening, is reported. Such information helps us to better understand how these compounds are produced in plants and may also enable us to develop novel strategies for improved apocarotenoid production in fruits or indeed, alternative production systems.

Microbial production of natural raspberry ketone.

Raspberry ketone is an important compound for the flavour industry. It is frequently used in products such as soft drinks, sweets, puddings and ice creams. The compound can be produced by organic synthesis. Demand for "natural" raspberry ketone is growing considerably. However, this product is extremely expensive. Consequently, there is a remaining desire to better understand how raspberry ketone is synthesized in vivo, and which genes and enzymes are involved. With this information we will then be in a better position to design alternative production strategies such as microbial fermentation. This article focuses on the identification and application of genes potentially linked to raspberry ketone synthesis. We have isolated candidate genes from both raspberry and other plants, and these have been introduced into bacterial and yeast expression systems. Conditions have been determined that result in significant levels of raspberry ketone, up to 5 mg/L. These results therefore lay a strong foundation for a potentially renewable source of "natural" flavour compounds making use of plant genes.

Potential role of glycosidase inhibitors in industrial biotechnological applications.

The nutrient content of food and animal feed may be improved through new knowledge about enzymatic changes in complex carbohydrates. Enzymatic hydrolysis of complex carbohydrates containing alpha or beta glycosidic bonds is very important in nutrition and in several technological processes. These enzymes are called glycosidases (Enzyme Class 3.2.1) and include amylases, pectinases and xylanases. They are present in many foods such as cereals, but their microbial analogues are often produced and added in many food processes, for instance to improve the shelf-life of bakery products, clear beer, produce glucose, fructose or dextrins, hydrolyse lactose, modify food pectins, or improve processes. However, many plant foods also contain endogenous inhibitors, which reduce the activity of glycosidases, in particular, proteins, peptides, complexing agents and phenolic compounds. The plant proteinaceous inhibitors of glycosidases are in focus in this review whose objective is to report the effect and implications of these inhibitors in industrial processes and applications. These studies will contribute to the optimisation of industrial processes by using modified enzymes not influenced by the natural inhibitors. They will also allow careful selection of raw material and reaction conditions, and future development of new genetic varieties low in inhibitors. These are all new and very promising concepts for the food and feed sector.