No abstract

Little is known about the impact of temperature on proanthocyanidin (PA) accumulation in grape skins, despite its significance in berry composition and wine quality. Field-grown grapes (cv. Merlot) were cooled during the day or heated at night by +/–8 °C, from fruit set to véraison in three seasons, to determine the effect of temperature on PA accumulation. Total PA content per berry varied only in one year, when PA content was highest in heated berries (1.46 mg berry−1) and lowest in cooled berries (0.97 mg berry−1). In two years, cooling berries resulted in a significant increase in the proportion of (–)-epigallocatechin as an extension subunit. In the third year, rates of berry development, PA accumulation, and the expression levels of several genes involved in flavonoid biosynthesis were assessed. Heating and cooling berries altered the initial rates of PA accumulation, which was correlated strongly with the expression of core genes in the flavonoid pathway. Both heating and cooling altered the rate of berry growth and coloration, and the expression of several structural genes within the flavonoid pathway.

No abstract

The presence of phenolic compounds in food has garnered much attention over the years. The diversity of these compounds and their contribution to nutritive and sensory qualities has been investigated in depth to elucidate benefits and modes of action. This review is intended to provide information on the impact of growing conditions on the accumulation of phenolics in plants. The aim is to provide knowledge of factors that influence phenolic biosynthesis in plants to help us manage them prior to harvest. Through improving our understanding of plant responses to the environment we may be able to manipulate growing parameters to suit the needs of the consumer. In this review, research regarding plant responses to climate, farming practices, biotic, and abiotic stresses is presented.

Antioxidant-rich foods and beverages play an essential role in the prevention of diseases. This study assessed the influence of the addition of ethanolic extract of propolis (EEP) to beer at different concentrations (0.05, 0.15, and 0.25 g/L). Total phenolic content (TPC) and total flavonoid content (TFC) were determined. Antioxidant activity (AA) was evaluated by radical scavenging activity (DPPH and ABTS) and reducing power (FRAP). The addition of EEP in beer resulted in a linear increase in the TPC with values of 4.5%, 16.7%, and 26.7% above a control (no EEP added; 242 mg gallic acid equivalent/L). A similar increase was observed with TFC values 16.0%, 49.7%, and 59.2% above the control (16.9 mg quercetin equivalent/L). The FRAP assay indicated linear increases in AA relative to control with values of 1555, 1705, and 1892 mol Trolox equivalent/L following EEP additions. The incorporation of EEP resulted in increases in the bioactive compounds and AA in beer without altering the physicochemical parameters of golden ale beer. The results indicate a promising use of propolis extract as a functional ingredient in beer.