Calcium lactate treatment of fresh-cut butternut squash (Cucurbita moschata): effect on texture during storage and shelf life

Abstract

Butternut squash (Cucurbita moschata), originating from Mexico belongs to the Cucurbitaceae family and is mainly grown in Mpumalanga and Gauteng provinces of South Africa. Two cultivars of butternut squash, ‘Atlas’ and ‘Pluto’ are widely cultivated and used for minimal processing by fresh-cut produce manufacturers in South Africa. Despite the increasing popularity and global market share for fresh-cut produce due their convenience, sensory properties and nutritional profiles, fresh-cut products experience rapid quality deterioration during storage. In this research, exacerbated texture quality deterioration during storage of fresh-cut butternut squash which led to economic losses at a South African based food processing plant was noted. Consequently, the effects of calcium lactate dipping treatment on texture quality and shelf life of fresh-cut butternut squash (Cucurbita moschata) cultivars ‘Atlas’ and ‘Pluto’ was investigated in this study. The investigation was divided into two subsequent experimental trials: the first was aimed at determining the impact of calcium lactate treatments (0.5% and 3% w/v; for 10 minutes at 50-60°C dipping temperatures) on fresh-cut butternut texture quality during storage (3.5°C) and investigating texture quality differences between ‘Atlas’ and ‘Pluto’ fresh-cut butternut. The second experimental trial was aimed at investigating the impact of 10°C storage temperature on the texture quality of fresh-cut butternut squash. Butternut squash cultivars ‘Atlas’ and ‘Pluto’ also underwent physical and physicochemical characterization. In both research experiments fresh-cut butternut sensory quality was evaluated by a trained descriptive panel while the microbiological quality was assessed through testing for total viable counts, Escherichia coli (O157:H7), coliforms, Listeria species, yeasts and moulds. There v were no significant differences (p>0.05) brought about by calcium lactate dipping treatments in terms of texture quality and shelf life for both ‘Atlas’ and ‘Pluto’ butternut squash in the first experiment. Furthermore, no significant differences (p>0.05) in terms of firmness and shelf life were established between ‘Atlas’ and ‘Pluto’ fresh-cut butternut squash as determined by the descriptive sensory panel. In the second experiment, a significant texture quality (firmness) difference (p<0.05) was observed between the controls and calcium lactate treated (0.5% and 3% w/v) fresh-cut butternut stored at 10°C. This study provided evidence that texture quality retention challenges during storage of fresh-cut butternut squash could better be addressed by adhering to strict cold chain parameters rather than application of calcium lactate dipping treatments at 0.5% and 3% concentrations. In addition, results from this research suggest that there is no variation between butternut squash cultivars ‘Atlas’ and ‘Pluto’ in terms of physicochemical properties, minimal processability, texture quality and shelf life. Further research can explore the application effect of more concentrated calcium lactate solutions (>3% w/v), prolonged dipping times (>10 minutes), higher dipping temperatures (>60°C) and/or a combination thereof in retaining texture quality of fresh-cut butternut squash cultivars.