Mark A. Kelm

Detailed Characterization of Proanthocyanidins in Skin, Seeds, and Wine of Shiraz and Cabernet Sauvignon Wine Grapes (Vitis vinifera)

The distribution of proanthocyanidin (PA) polymer lengths, proanthocyanidin concentration at each polymer length, and polymer composition were determined in the seed, skin, and wine of Shiraz and Cabernet Sauvignon grape berries grown in southeast Australia. PA was fractionated by semipreparative high performance liquid chromatography (HPLC) and analyzed by phloroglucinolysis and HPLC to report the degree of polymerization (DP), concentration, and composition at 11 DP values in seed and wine and 21 DP values in skin. In skin, the highest PA concentration was observed at a DP of 31 in Shiraz and 29 in Cabernet Sauvignon representing 15% of the total PA in both varieties. The distribution of seed PA had the highest concentration at a DP of 7 in Shiraz and 6 in Cabernet Sauvignon representing around 30% of the total PA. In the wine PA distribution, the highest concentration was observed at a DP of 11 in Shiraz and 9 in Cabernet Sauvignon representing around 26 and 32% of the distribution, respectively. A second peak in wine PA concentration was observed at the largest DP of 18 in Shiraz and 15 in Cabernet Sauvignon representing around 20% of the distribution. The composition in wine did not vary at different DP, but the proportion of epicatechin gallate varied in seed PA less than 4 DP. The proportion of epigallocatechin increased with increasing DP in skin PA. Wine PA had a DP range and composition similar to the distribution of skin PA between DP 4 and 18 suggesting that larger skin PAs are not extracted into wine. This study provides information that could be used to target the important PA fractions in grapes that need to be measured to understand (or predict) PA extraction into wine and eventual mouthfeel.

Identification and quantitation of flavanols and proanthocyanidins in foods: how good are the datas?

Evidence suggesting that dietary polyphenols, flavanols, and proanthocyanidins in particular offer significant cardiovascular health benefits is rapidly increasing. Accordingly, reliable and accurate methods are needed to provide qualitative and quantitative food composition data necessary for high quality epidemiological and clinical research. Measurements for flavonoids and proanthocyanidins have employed a range of analytical techniques, with various colorimetric assays still being popular for estimating total polyphenolic content in foods and other biological samples despite advances made with more sophisticated analyses. More crudely, estimations of polyphenol content as well as antioxidant activity are also reported with values relating to radical scavenging activity. High-performance liquid chromatography (HPLC) is the method of choice for quantitative analysis of individual polyphenols such as flavanols and proanthocyanidins. Qualitative information regarding proanthocyanidin structure has been determined by chemical methods such as thiolysis and by HPLC-mass spectrometry (MS) techniques at present. The lack of appropriate standards is the single most important factor that limits the aforementioned analyses. However, with ever expanding research in the arena of flavanols, proanthocyanidins, and health and the importance of their future inclusion in food composition databases, the need for standards becomes more critical. At present, sufficiently well-characterized standard material is available for selective flavanols and proanthocyanidins, and construction of at least a limited food composition database is feasible.

Effect of Cocoa and Chocolate Beverage Consumption on Human Cardiovascular Health

Cocoa and chocolate have a rich history of use as both a medicine and a vehicle to deliver other medicines. This was, and still is in some communities, in the context of a traditional medicine popular in Central America. In addition, many of these uses were transferred and modified for approximately four centuries in Europe after New World contact. Interestingly, chocolate was consumed predominantly as a beverage; its now-familiar solid format appeared later as a result of food manufacturing innovation in Europe during the 19th century. However, the standard cocoa and chocolate beverage formats we are familiar with bear little, if any, resemblance to the recipes developed by ancient Central Americans. Dillinger et al. (1) convincingly illustrate the versatility of cocoa and chocolate as medical and nutritional uses in their research. As shown in Table 1, the number of different indications, multiplied by different preparations in the accompanying text, is impressive. Continuing research by Dillinger et al. and others on the use of these products by the native populations before European contact may provide additional and important insights on cocoa’s cultural origins and geographical aspects and its medical uses (L. Grivetti and H. Yana-Shapiro, personal communication).