Polyphenolic Content and Color of Seedless and Seeded Shade Dried Chinese Raisins

Abstract

grape cultivars, of seeded and seedless raisins from black, reddish-brown and yellowish-green grape varietieswere examined to determine the relationship between grape color, seeded status and raisin phenolic content. The raisins were analyzed for phenolic profile, total phenolic (TP) and flavonoid contents (TF), and antioxidant activities (DPPH, ABTS and FRAP). We found that despite the perception that dark colored raisins, contain higher levels of polyphenolic antioxidants, only seedless raisins from black grapes were higher in TP. Black raisins exhibited significant higher values of TP and FRAP activity than reddish-brown and yellowish-green raisins. The values of TP, TF, DPPH, ABTS, and FRAP capacities for seeded raisins were higher than those of seedless samples. Raisins could be classified into three groups and some raisins differing in seed-bearing status or color were grouped together, indicating the antioxidant properties of raisins were not only determined by raisin color, but also by their seedbearing status.Keywords: Raisin, polyphenol, color, seeded status, antioxidant capacity IntroductionChina is the world's third largest producer of raisins after the U.S. and Turkey. Most grapes are grown in Xinjiang province, China's largest province, spanning an area the combined size of France, Spain, Italy, and Germany or the six western states of the USA. The large geographical area encompasses diverse climatic zones requiring grapes varieties that are adapted to these zones.Xinjiang Province is the largest producer of green raisins . Green raisins are highly preferred by Chinese consumers over imports even though they command a higher price because of their flavor and appearance.Raisins rank the highest in concentration of total phenolic compounds and antioxidant activities among solid fruit products (Williamson and Carughi 2010;Karakaya 2001). Thompson seedless is the variety most widely grown in the world including China for both dark and green raisin production, however, other grapes such as Muscat or black grapes such as black Corinth are also grown for specialty markets. Darker colored grapes and raisins are often perceived to have higher levels of "antioxidants" and perceived to be healthier. The interest in health benefits related to polyphenolic compounds have resulted in studies of the polyphenolic content of grape varieties. Breksa et al. (2010) analyzed the polyphenol content of white grapes from six commercial U.S. varieties and ten potential selections for raisin D. Shao et al. 360 production (Breksa III et al. 2010). The composition of the fresh grapes, but not raisins were analyzed, cafteric acid also called monocaffeyltartaric acid, a phenolic acid and not a polyphenol compound, predominates in fresh grapes but is typically absent in raisins. Baiano and Terracone (2011) analyzed the polyphenol content of peels, seeds and juice of fresh grapes: four white and three red/black varieties. In seeded varieties the content of total polyphenols was 3 _ 5 times higher in seeds than in skins. The r...

Study on quality parameters of grapes (Vitis vinifera) and raisins affected by grape type

“…Black seeded grapes contain phenols in seeds and skin so the raisins made from black seeded grapes were found with higher content while raisins obtained from white grapes like Thompson Seedless, Manjari Naveen and Manjari Kishmish. Same type results were obtained by Shao et al (2016) and noted large variations in phenolic compounds and their contents among different raisins. Sharma et al (2018) stated that the coloured seeded varieties have higher antioxidant properties than seedless varieties.…”

“…Black raisins contained significantly higher values of TP and antioxidant activities than reddish-brown and yellowishgreen raisins. Moreover, seeded raisins contained much higher phenols and showed better antioxidant activities than seedless samples (Shao et al 2016). Black seeded grapes contain phenols in seeds and skin so the raisins made from black seeded grapes were found with higher content while raisins obtained from white grapes like Thompson Seedless, Manjari Naveen and Manjari Kishmish.…”

Bioactive Properties of Different Parts of Vitis labrusca L. Fruit

“…The antioxidants in the samples act as reductants in a redox-linked colorimetric reaction. The value reflects the reducing power of the antioxidants (Shao et al, 2016). The extract has the ability to scavenging of free radicals thanks to hydrogen donation.…”

Effect of Pretreatment and Drying on the Nutritional and Functional Quality of Raisins Produced with Seedless Purple Grapes

“…Raisins, recognized for their delightful taste and substantial nutritional value, rank as one of the most significant and favored dried fruits globally [3]. China stands as the world's third-largest raisin producer, with Xinjiang Province leading in raisin production [4]. At present, common drying methods include shade drying, sun drying, and hot-air drying [5].…”