Effect of Compost Socks System on Antioxidant Capacity, Flavonoid Content, and Fruit Quality of Strawberries

Authors: Wang, Shiow; Millner, Patricia

Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/3/2009
Publication Date: 9/22/2009
Citation: Wang, S.Y., Millner, P.D. 2009. Effect of Compost Socks System on Antioxidant Capacity, Flavonoid Content, and Fruit Quality of Strawberries. Journal of Agricultural and Food Chemistry. 57:9651-9657.

Interpretive Summary: Strawberries are susceptible to numerous disease problems. Previous research demonstrated that treatment of soil with vinegar and addition of compost to the surface of strawberry beds helped to reduce the incidence and severity of strawberry plant root diseases. Data are not available to document the influence of this new cultural practice on fruit quality and potential nutritive value. Specifically, we wanted to know how antioxidants are affected because antioxidants have been shown to promote human health. We found that strawberries grown in the new system had more antioxidants. They also had more chemicals (flavonoids and anthocyanins) which give better color and higher nutritive value. In most cases, the strawberries had more sugar and citric acid, important to flavor. However, in some cases, sugar was lower. These results are important to researchers and growers who might like to use the new system to control diseases.

Technical Abstract: The effect of cultivation practices on fruit quality, antioxidant capacity, and flavonoid content in strawberries cv. Allstar and Chandler was evaluated. Strawberry fruit used in this study were from plants grown in soils which had prior history of black root rot and red stele and had not been fumigated during the seven years prior to the study. Results from this study showed that different cultural systems (matted row, black plastic mulch and compost socks) significantly affected total anthocyanins and total phenolics in strawberries. Fruit from plants grown in compost socks had significantly higher oxygen radical absorbance capacity (ORAC) than fruit from black plastic mulch or matted row systems. Individual flavonoids and anthocyanins were also higher in strawberries grown in compost socks than those grown in black plastic mulch or matted row systems. Higher levels of ellagic acid, ellagic acid glucoside, p-coumaroyl-glucose, quercetin 3-glucoside and quercetin 3-glucuronide, kaempferol 3-glucoside and kaempferol 3-glucuronide were also found in fruit grown from compost socks than those from other systems. Strawberry plants grown in compost socks also produced fruit with significantly higher soluble solids content, titratable acid, total sugars, fructose, glucose, sucrose, and citric acid than fruits produced in the two other culture systems. In general, cv. Chandler surpassed cv. Allstar in content of sugars, acids and flavonoids regardless of pre-planting vinegar drenching and various culture treatments. However, pre-planting vinegar treatment increased acidity, and cyanidin-based and pelargonidin-based anthocyanins, but decreased sugar content in fruit of both cultivars.