Designed mixed model approach for efficient antioxidant extraction from pomace

Abstract

Pomace is a waste product of juice production, but still holds many valuable compounds, such as e.g. antioxidants. However, efficient extraction proves to be challenging as extractability is highly dependent on experimental conditions. Furthermore, antioxidants are also often retained by structural polysaccharides. Consequently, this study investigates the extractability of antioxidants in five different types of pomace in a 2 x 2 x 2 x 3 full factorial fully replicated design to determine the most efficient way of extraction. Therefore, extracting agent, temperature, extraction method as well as the use of enzyme were alternated to investigate the effects of these parameters on the extractability. Main effects as well as interaction effects were estimated with linear mixed models. To study the effects of polysaccharides on the retention of antioxidants, the number of soluble polysaccharides was measured as well and correlated with the increase in antioxidants after enzyme application. The experiments showed that acetone was most suitable as an extracting agent and that the use of pectinase significantly increased the amount of extracted antioxidants. Additionally, ultrasound-assisted extraction is advantageous compared to extraction in water baths. Temperature showed the smallest effect in this experimental design. Lastly, the results also highlight that the amount of soluble polysaccharides do not correlate with the extractability of antioxidants.