Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 9, 2013
Publication Date: March 1, 2014
Citation: Harshman, J.M., Jurick Ii, W.M., Lewers, K.S., Wang, S.Y., Walsh, C.S. 2014. Decay resistance to Botrytis cinerea and quality characteristics during storage of raspberry genotypes. HortScience. 49:311-319. Interpretive Summary: Red raspberry is a highly valued fruit that deteriorates very quickly in storage, reducing quality of fruit presented in the market and eaten by consumers. Consumers are interested in raspberry fruit available in other colors, such as black, purple or yellow raspberries, either for the novelty or for perceived increased health benefits. Increased knowledge of how the novel-colored raspberries deteriorate in storage after harvest, and how that deterioration rate is affected by weather prior to harvest, would allow more attractive and better quality fruit to reach the consumer. This research compared red, black, purple, and yellow raspberry fruit to understand how each deteriorated in storage with regard to color, firmness, fungal decay, juice leakage, sweetness, tartness, and antioxidant levels. We found that the different raspberry color groups deteriorated differently from each other in storage. Yellow raspberries had the worst decay rates while some black and purple raspberries resisted decay the longest. We also found that different aspects of the weather prior to harvest, such as rainfall, humidity, and temperature, affected each raspberry color group differently during storage. The information will be of interest to raspberry growers and those who package and market raspberries in addition to scientists who study raspberries and food storage.
Technical Abstract: Raspberries are a delicate, high value crop with an extremely short shelf life exacerbated by postharvest decay caused by Botrytis cinerea Pers. European red raspberry (Rubus idaeus L.) is the most widely grown. Yellow (R. idaeus L.), black (R. occidentalis L.) and purple raspberries (R. ×neglectus Peck. or R. occidentalis ×idaeus hybrids) are available mainly at local markets and U-pick farms. To compare the postharvest quality of the raspberry color groups, pesticide-free fruit from cultivars and breeding selections of red, yellow, purple, and black raspberries were examined for ORAC, phenolics, anthocyanins, soluble solids, titratable acids, pH, color, firmness, decay and bleed rates, ethylene evolution and respiration. There were significant correlations between decay rate and physiochemical properties. Both decay and bleed rates were correlated with weather conditions before harvest, but each color group responded differently to different weather factors. There were no correlations between changes in color, firmness, decay or bleed rates. All the other color groups were less tart than the familiar red raspberry. Yellow raspberries had the worst decay rates but the best bleed rates. Black and purple raspberries, with the highest phenolics and anthocyanins and the lowest ethylene evolution rates, resisted decay the longest, but bled soonest.