Plum-grape like

Several attempts have been made to obtain a more complete picture of the phenolic composition of a sample. For this purpose some researchers propose the conductance of several complementary assays [106]. More popular is the formation of ratios which are claimed to correlate with the relative degree of polymerization. Considering the complex reaction scheme of these assays, interpretations of such ratios must be performed very carefully. In our opinion, some of them more likely reflect the specific proanthocyanidin structures than actual relative degrees of polymerization. In the last few years the following ratios have been described in the literature dimethylaminocinnamaldehyde / proanthocyanidin ratio for wine and grape tissue [149], vanillin / dimethylaminocinnamaldehyde ratio for wine and purified standards [96] and proanthocyanidin / vanillin ratio for plums [95] as well as purified proanthocyanidins from various plant sources [155]. 

Table II shows that sucrose levels are highest in peach fruit and very low in blackberry, cherry, and grape. The % C.V. for sucrose content for many of the fruit samples is extremely high, most likely because of enzymic or chemical hydrolysis. The average sucrose content of plum fruit is 38 of total sugars, while processed plums contain only 1. Presence of large quantities of sucrose in prune juice has, in fact, been used as an indication of adulteration ( ). Cherries and grapes contain invertase Cllj 12) which may account for sucrose not being detected in some samples and may also explain the high % C.V. for those fruits. In examining apple Juice concentrates, we did not detect sucrose in seven-fold concentrates whereas we did in fo ar-fold apple concentrates (7.) > the time-temperature conditions allowing for complete hydrolysis in the more concentrated product.

Flavonols, like anthocyanidins, exist almost exclusively as glycosides. Three common flavonols are kaempferol, quercetin, and myricetin, resembling pelargonidin, cyani-din, and delphinidin, respectively, in the hydroxylation pattern of the B ring. Flavonol glycosides impart weak yellow hues to apples, apricots, cherries, cranberries, grapes, onions, plums, potatoes, strawberries, tea, tomatoes, and other commodities. 

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