EFFECT OF ULTRASOUND-ASSISTED MASHING ON THE PHYSICOCHEMICAL AND FUNCTIONAL PROPERTIES OF A FERMENTED BEVERAGE FROM GERMINATED PUMPKIN SEED FLOUR

The growing demand for functional plant-based beverages has encouraged the use of alternative raw materials, such as pumpkin seeds, which are rich in proteins, fibers and bioactive compounds. In this context, the use of ultrasound (US) during mashing emerges as a promising strategy to intensify nutrient extraction through the cavitation, which promotes cell disruption. This study aimed to evaluate the effect of US-assisted mashing on the physicochemical and functional properties of water-soluble extracts (WE) obtained from germinated pumpkin seed flour. Pumpkin seeds were subjected to either conventional hydration or intermittent ultrasound-assisted hydration (two 10-minute cycles at 25 or 45 °C, 38 W/L, 25 kHz) at a 1:3 (m/v) ratio, followed by germination (3 days at 25 °C). Non-germinated seeds were used as the control. After drying and milling, the resulting flours were mixed with water (1:8 w/w) and subjected to mashing for 132 minutes using either a thermostatic or ultrasonic bath (38 W/L, 25 kHz), depending on the US application level (0%, 50%, or 100% of the total mashing time), with a temperature ramp ranging from 35 to 78 °C. The mixtures were then blended (2 min, 25 °C), filtered, thermally treated (121 °C/15 min), and fermented with Lacticaseibacillus rhamnosus at 42 °C until pH 4.6. The beverages were evaluated for physicochemical parameters, lactic acid bacteria (LAB) counts, color, total phenolic compounds (TPC) and antioxidant activity (ABTS and DPPH) over 15 days of storage at 5°C. The pH and acidity remained stable throughout storage (p>0.05). LAB counts did not differ among treatments (p>0.05), remaining above 8.52 log CFU/mL after production and increasing after 15 days (>9.13 log CFU/mL; p<0.05). Color was influenced by germination and US-assisted mashing, especially at 50% US, which yielded lighter (L* up to 78.5; 20.4% increase) and more visually appealing beverages (higher a* and b* values; p<0.05). Regardless of storage time, germinated and sonicated samples showed higher TPC (up to 125% increase) and antioxidant activity (up to 387% for ABTS and 382% for DPPH) compared to control, especially those that were germinated with US intervention and mashed under US (50% or 100%), reaching up to 63.1 mg EAG/100 mL (TPC), 213.7 µmol Trolox/100 mL (ABTS) and 127.3 µmol Trolox/100 mL (DPPH). These results confirm that combining germination and ultrasound enhances fermentation, microbiological stability, and functional potential of vegetable beverages obtained from germinated pumpkin seed flour, representing a promising strategy for non-dairy functional foods development.