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Abstract
Pecan is a high fat hickory nut which is susceptible to rapid physical and chemical deterioration, affected by post-harvest conditions. Some of the external factors such as relative humidity (RH), temperature of the surrounding environment and storage duration are the major factors affecting pecan quality. The aim of the project is to study quality changes during storage. Three cultivars (Stuart, Pawnee and Desirable) were stored at various temperatures (0°C to 40°C), relative humidity (RH, 30% to 90%) and packaging materials (LDPE, PE, laminate, PE-Nylon). The effect of environmental conditions was studied and changes in pecan color, texture and lipid oxidation status during storage was explored. For the first time, effect of RH on pecan color was explored. It was recorded that under high RH conditions (>50%), rate of color deterioration increased, and pecans turned dark brown as opposed to reddish brown under low RH conditions (<50%). The extent and difference in storage stability under varying environmental condition was explored via sensory evaluation. The pecans stored in metallic laminates (with N2 flushing) experienced least color, aroma, texture and lipid oxidation degradation (even under extreme conditions i.e., 40°C storage temperature) followed by PE-Nylon (vacuum packed) and LDPE. The computer-aided predictive models were developed to estimate changes in pecan quality (color, texture, lipid oxidation status and sensory) at different storage and packaging conditions. For the first time, artificial neural network model was developed, capable of estimating sensory perception score (from human’s perspective) based on concentration of volatile compounds present in pecans and/or generated during storage. These models has been made available online for free use to researchers, pecan growers and processors. This information will allow pecan growers and processors to select best storage conditions and packaging methods for improved quality and extended shelf life of pecan products. The results from this project will contribute to a more consistent and sustainable supply of pecan and ensure that the US pecan industry remains competitive in the international marketplace.