Ultrasound and microwaves reduce stress in probiotics during avocado drying: Impact on mass transfer and cell viability

This study aimed to investigate the effects of ultrasound and microwave pre-treatment on the avocado structure and the incorporation of Bifidobacterium animalis ssp. lactis (BAL) (B94) for subsequent drying in a 60 °C oven. In addition to the probiotic incorporation into avocado, the functional, structural, and thermal properties of the product were studied. The incorporation of BAL (B94) was facilitated especially in microwave-treated samples that maintained higher cell viability throughout the process (>6 log CFU/g). The dehydrated avocado slices with probiotics showed higher levels of total phenolic compounds (3.28–9.65 mg GAE/100g), total carotenoids (0.83–1.19 mg/100g), antioxidant activity (6.47–11.22 μmol TE/g), as well as higher rehydration ratio (1.96–3.31 g/100g) and lower firmness (22.53–35.18 N). Ultrasound and microwave pre-treatments applied to avocado slices, followed by immersion in probiotic solution, significantly accelerated the drying process. This resulted in a significant reduction in time (690 and 450 min) and energy consumption (5.33 and 3.82 kW h/kg) while increasing effective diffusivity (9.81 and 12.40 × 10−10 m/s2) compared to the control group. The structural and thermal properties of avocado slices differed, indicating a high melting point in the crystalline network. These findings offer new possibilities for the food industry, suggesting that ultrasound and microwave can influence the formation of intracellular spaces within the avocado, providing a protective environment for probiotics and mitigating the adverse effects of stress during the drying process. •Non-dairy probiotic avocado snack was developed.•Ultrasound (US) and microwave (MW) treatments altered avocado tissue, improving probiotic distribution in snack.•US and MW accelerated the mass transfer process and reduced energy consumption.•Dehydrated product showed probiotic viability >6 log CFU/g.