Physicochemical and structural characterisation of fermented pumpkin purees: a sustainable approach to pulp utilisation

Abstract

• Processing transforms Moscata and Styriaca pumpkin pulps • Fermentation modulates structure and rheology of purees • β-carotene stability preserved during fermentation of Moscata • Cultivar-dependent responses drive texture and flow behaviour • Pumpkin pulp valorisation supports sustainable food design This study focused on pumpkin pulp as a promising raw material for the development of value-added plant-based foods in the context of the sustainable utilization of underutilized biomass. In this context, the influence of blanching, sterilization, and lactic acid fermentation using Pediococcus pentosaceus on pumpkin purees from two pumpkin cultivars of different technological relevance, namely, the carotenoid-rich pumpkin variety Cucurbita moschata and the oil pumpkin variety Cucurbita pepo var. styriaca , was studied. Structural, physicochemical, and chemical properties were evaluated. The results showed that the fermentation process resulted in a significant decrease in pH, as the pH values decreased from 6.8 to 4.2 and 5.9 to 4.3 for fermented Moscata puree and fermented Styriaca puree, respectively. Moreover, the fermentation process affected the particle size distribution and rheological properties of the pumpkin purees. On the other hand, the β-carotene content remained relatively stable during the processing steps, especially in the purees of the variety C. moschata , which reached values of up to 31.55 ± 0.08 μg/g f.w. Raman spectroscopy combined with principal component analysis (PCA) enabled clear differentiation between processing treatments and cultivars, explaining 87% of the variance. The results of this study demonstrate that the thermal processing and controlled lactic acid fermentation of pumpkin purees affect the microstructure and rheology of the pumpkin purees while retaining the β-carotenoid content.