WINETECH Technical Yearbook 2019

components found in wine which contribute to this health benefit still remain to be delineated (Opie & Lecour, 2007). Ischemic heart disease, commonly referred to as a heart attack, is associated with cellular death of the heart tissue which, function to its extent, will compromise the pumping activity (cardiac function) of the heart. With the vision to better understand the cardiovascular benefits of chronic and moderate consumption of wine, we have established a preclinical model mimicking a heart attack by using an isolated heart model in rats that were pre-treated with wine at a dose equivalent to 2-3 glasses of wine per day in humans. In this model, we compared the cardiovascular protective effect of a red wine with 12% alcohol before and after alcohol removal to 6%, using the reverse osmosis technique. To our surprise, the wine with 6% alcohol offered as much cardiovascular protection as the 12% wine, both wines increasing the cardiac function by approximately 60% compared to a pre-treatment with water only. Our data therefore strongly suggest that alcohol in wine may not be the primary component

contributing to the cardiovascular benefit of wine (Lamont et al ., 2012). ABOUT RESVERATROL Resveratrol, a polyphenol found in wine, is a strong antioxidant we l l known for i t s mu l t i p l e health benefits. Produced in the skin of grapes, this phytoalexin is mainly found in red wine a t c o n c e n t r a t i o n s v a r y i n g between 0 . 2 and 5 . 8 mg /L , depending mainly on the grape var i ety and the winemak ing process. Although resveratrol possesses strong cardiovascular properties, its contribution into the cardiovascular benefit of moderate and chronic moderate consumption of wine remains to be demonstrated, as most of the cardiovascular benefits o f r e s v e r a t r o l h a v e b e e n demonstrated for concentrations o f r e s v e r a t r o l a b o v e i t s concentration found in wine (Lamont et al ., 2011; Lamont & Lecour, 2011). ABOUT MELATONIN M e l a t o n i n ( N - a c e t y l - 5 - methoxytryptamine) is another component in wine that has attracted attention in the past

f ew ye a r s . T h i s h o rmo n e , produced in both humans and plants, is well known for its role in the regulation of our sleeping pattern . Synthet i sed ma i n l y in the brain at night, it triggers our sleep by modulation of the physiological circadian clock. I n p l ant s , the phys i o l og i ca l func t i ons of me l aton i n st i l l remain to be understood. As a strong antioxidant, the presence of melatonin in plants seems to protect it from stressful situations, such as drought, temperature changes or UV radiations. It is also suggested that melatonin may be key to enhance the development stage of the p l ant and the photosynthesis process (Arnao & Hernandez-Ruiz, 2015). Melatonin in wine was discovered in 2006 in both red and white wines, with melatonin levels reported to be highest in red wines, ranging from 2 pg/mL-500 pg/mL (Iriti et al ., 2006). In South African wines, similar levels of melatonin have been reported with a maximal concentration found in Pinotage (unpublished data) . The concent rat i on of melatonin is largely dependent on the type of grapes and the