Antioxidant Activities and Quality Characteristics of Mulberry Concentrate, Freeze-dried Mulberry, and Pomace

Abstract

Mulberry pomace, a by-product obtained from mulberry juice, has not been utilized as food. In this study, antioxidant activities, proximate composition and physiochemical characteristics of mulberry pomace were evaluated and compared with those of mulberry fruit or mulberry concentrate. Mulberry fruit was pressed and filtered. The filtrate and residue were used as mulberry juice and mulberry pomace, respectively. Mulberry juice was evaporated, after which a concentrate (24.7 o Brix) was obtained. Moisture contents of mulberry concentrate, freeze-dried mulberry, and pomace were 68.7%, 6.03%, and 7.32%, respectively. Reducing sugar contents were 45.7% in freeze-dried mulberry, 24.5% in pomace, and 30.9% in mulberry concentrate. The pH and acidity of the three samples ranged from 5.80～5.92 and, 0.035～0.080%, respectively. Carbohydrate and crude ash contents were the highest in mulberry fruit, whereas crude protein, fat, and fiber contents were the highest in pomace. Redness of the Hunter color system was 4.7 in mulberry and 4.3 in pomace. Total phenolic content was the highest in mulberry fruit, whereas total flavonoid content was the highest in pomace. Antioxidant activities (DPPH, hydroxyl, and ABTS radical scavenging activities) were enhanced in the order of mulberry fruit> pomace> mulberry concentrate. Especially, antioxidant activities, such as DPPH and hydroxyl radical scavenging activities, of mulberry pomace were similar with those of mulberry fruit. Based on these results, freeze-dried mulberry pomace may be considered as a functional as well as an additive material for food processing.

Effects of Freeze-dried Mulberry on Antioxidant Activities and Fermented Characteristics of Yogurt during Refrigerated Storage

“…Anthocyanins, the major pigment of mulberry are phenolic compounds reported to have various health beneficial effects including antioxidant properties, anti-diabetic effect and anti-bacterial effect ( Grace et al , 2009 ). In addition, mulberry extract contains organic acids, vitamin and minerals such as Ca, K and vitamin C ( Jeon et al , 2012 ). Nevertheless, one of the limitations of employing anthocyanin pigment, as a food colorant in food products, is its poor stability ( Yawadio and Morita, 2007 ).…”