Beer Molecules and Its Sensory and Biological Properties: A Review.

The production and consumption of beer plays a significant role in the social, political, and economic activities of many societies. During brewing fermentation step, many volatile and phenolic compounds are produced. They bring several organoleptic characteristics to beer and also provide an identity for regional producers. In this review, the beer compounds synthesis, and their role in the chemical and sensory properties of craft beers, and potential health benefits are described. This review also describes the importance of fermentation for the brewing process, since alcohol and many volatile esters are produced and metabolized in this step, thus requiring strict control. Phenolic compounds are also present in beer and are important for human health since it was proved that many of them have antitumor and antioxidant activities, which provides valuable data for moderate dietary beer inclusion studies.

Effect of ethylene and 1-methylcyclopropene on the postharvest behavior of cape gooseberry fruits (Physalis peruviana L.).

Cape gooseberry (Physalis peruviana L.) fruits are highly perishable berries that exhibit a climacteric respiratory behavior. The objective of this study was to evaluate the effect of ethylene and the ethylene action inhibitor 1-methylcyclopropene on the postharvest behavior of cape gooseberry fruits (ecotype Colombia). Fruits were treated with ethylene, in an ethephon application (1000 µL L-1), and pretreated with 1-methylcyclopropene (1 µL L-1), 1-methylcyclopropene+ethylene, and results compared with a control without application. Subsequently, the fruits were maintained at room temperature (20 ℃, 75% RH) for up to 11 days. The pretreatment of the cape gooseberry fruits with 1-methylcyclopropene delayed most of the ripening-associated parameters, with a reduction in the respiration rate and ethylene production, skin color development, total soluble solids, total carotenoid content, loss of firmness, loss of total titratable acidity and emission of volatile compounds such as ethyl octanoate, ethyl butanoate, ethyl decanoate, and hexyl decanoate. Conversely, application of ethephon accelerated most of these physiological changes and also overcame most of the effects prevented by the ethylene action inhibitor. Altogether, the results supported the idea of a climacteric-like behavior for cape gooseberry fruits and pointing out that the pretreatment with 1-methylcyclopropene may be a promising and efficient postharvest treatment to delay maturity and extend the postharvest period.

Producción de ésteres volátiles a través de tecnología de fermentaciones utilizando residuos cítricos / Volatile ester production using citrus waste through fermentation technology

La acumulación de residuos generados por las industrias procesadoras de alimentos, entre ellos, los residuos cítricos producidos en el procesamiento de jugos, constituyen una problemática desfavorable para el medio ambiente. En diversos países incluyendo Bolivia no existen gestiones que se apliquen al manejo y aprovechamiento de estos residuos, los cuales representan aproximadamente más del 50 % del total de la fruta, por ello es necesaria una gestión integrada de estos residuos de acuerdo al concepto de reducir, reutilizar y reciclar. En el Área de Biotecnología Microbiana del Instituto de Investigaciones Fármaco Bioquímicas, se estudia una alternativa de manejo y aprovechamiento de estos residuos cítricos, investigando la utilización de los mismos como materia prima para la producción de ésteres volátiles que tienen propiedades biosaborizantes. La conversión de residuos cítricos a biosabores se lleva a cabo mediante procesos biotecnológicos de fermentación de azúcares que involucran el uso de microorganismos como levaduras. Para ello, se plantea el estudio del comportamiento cinético de Cándida maltosa asociado a su capacidad de producir ésteres volátiles, considerando que esta levadura es capaz de formar biopelículas como forma de protección ante compuestos inhibitorios propios de la materia prima.

The accumulation of wastes from food processing industries, among them the citrus residues from the juice-processing industry becomes an issue due to its unfavorable impact for the environment. Several countries including Bolivia do not have alternatives for waste management. The citrus waste accounts 50% of the fruit. Therefore,an integrated procedure under the concept to reduce-reuse-recycling is needed.An alternative for management and reuse of citric waste is planned at the Microbial Biotechnology Area of Instituto de Investigaciones Fármaco Bioquímicas. Moreover, the utilization of citrus waste as feedstock for the production of volatile esters, with flavoring properties, is being researched.The conversion of citrus waste to bioflavors can be carried out by sugars-fermenting yeast through biotechnology. Therefore, studies involving the kinetic behaviour of Candida maltosa associated to volatile ester production are planned. This yeast is able to form biofilm as a protection skill against inhibitory compounds from the feedstock.

Production of sensory compounds by means of the yeast Dekkera bruxellensis in different nitrogen sources with the prospect of producing cachaça.

The distilled spirit made from sugar cane juice, also known as cachaça, is a traditional Brazilian beverage that in recent years has increased its market share among international distilled beverages. Several volatile compounds produced by yeast cells during the fermentation process are responsible for the unique taste and aroma of this drink. The yeast Dekkera bruxellensis has acquired increasing importance in the fermented beverage production, as the different metabolites produced by this yeast may be either beneficial or harmful to the end-product. Since D. bruxellensis is often found in the fermentation processes carried out in ethanol fuel distillation in Brazil, we employed this yeast to analyse the physiological profile and production of aromatic compounds and to examine whether it is feasible to regard it as a cachaça-producing microorganism. The assays were performed on a small scale and simulated the conditions for the production of handmade cachaça. The results showed that the presence of aromatic and branched-chain amino acids in the medium has a strong influence on the metabolism and production of flavours by D. bruxellensis. The assimilation of these alternative nitrogen sources led to different fermentation yields and the production of flavouring compounds. The influence of the nitrogen source on the metabolism of fusel alcohols and esters in D. bruxellensis highlights the need for further studies of the nitrogen requirements to obtain the desired level of sensory compounds in the fermentation. Our results suggest that D. bruxellensis has the potential to play a role in the production of cachaça.