Feasibility of creating compression‐molded biocomposite boards from berry fruit pomaces

In this study, we investigated the feasibility of creating biocomposite boards from berry fruit pomaces on the basis of a crosslinking mechanism. Blueberry, cranberry, and wine grape pomaces were ground, dried, and mixed with soy flour (SF) or pectin and xanthan gum mixture at a ratio of 1 : 1 and with the addition of 15% glycerol (w/w of pomace and SF). Blueberry pomace (BP) was also blended with NaOH‐modified soy flour (MSF) at pomace/MSF ratios of 1 : 1, 4 : 1, and 9 : 1 and with 5, 10, or 15% glycerol. The mixtures were compression‐molded at 130–140°C into biocomposite boards to evaluate their mechanical and thermal properties, water absorption and solubility, and microstructure. Among the three pomaces, the BP board was the stiffest, whereas the wine grape pomace board was the most flexible. The breaking strength and modulus of elasticity of the BP/MSF boards increased with increasing MSF concentration but decreased with increased glycerol concentration. Mixing the pomace and glycerol into SF shifted the endothermic peaks and initial degradation to lower temperatures compared to that of SF alone. Increasing the glycerol concentration decreased the water absorption but increased the water solubility of the BP/MSF board. The pomace/MSF ratio in the board did not affect (P > 0.05) the water absorption, but the water solubility increased with increasing pomace concentration. Glycerol addition in the BP/MSF board smoothed the fracture surface, as shown by scanning electron microscopy images. This study may provide an approach to reducing fruit pomace disposal through the development of new value‐added biodegradable products for industrial applications, such as nursery pots and egg cartons. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010