Ultrasonic pre-treatment to enhance drying of potentially probiotic guava (Psidium guajava): Impact on drying kinetics, Lacticaseibacillus rhamnosus GG viability, and functional quality.

This study aimed to evaluate the effects of ultrasound (US) on the drying acceleration of potentially probiotic guava, including its impact on drying kinetics, probiotic (Lacticaseibacillus rhamnosus GG) viability, and functional quality of the product during drying. To perform US pre-treatments, one group of samples were first pre-treated by US (38 W/L, 25 kHz) for 15 and 30 min and then immersed in the probiotic solution for 15 or 30 min, and another group of samples were submerged in the probiotic solution simultaneously applying US (US-assisted) for 15 and 30 min. After pre-treatments, the samples were convectively dried at 60 °C. Based on the results, all US pre-treatments improved the drying rate (up to 59%) and reduced the drying time (up to 31%) to reach 25% moisture compared to non-sonicated samples. The reduction in drying time (from ∼6 h to ∼4 h for US pre-treated samples) was crucial for maintaining the probiotic viability in the dehydrated guavas. These samples showed counts of 6.15 to 7.00 CFU∙g-1 after 4 h, while the control samples reached counts of 4.17 to 4.45 CFU∙g-1 after 6 h. US pre-treatment did not affect the color parameters of the samples before drying (p > 0.05). The functional compounds were reduced during drying (p < 0.05), however, all US pre-treated samples had lower reductions in vitamin C content (up to 20%), phenolic compounds (up to 41%) and antioxidant capacity (up to 47%) compared to control samples (up to 52%, 81% and 61%, respectively). Therefore, US pre-treatment (highlighting the US-assisted probiotic incorporation for 30 min) reduced the drying time for guava slices and minimized the thermal impact on probiotic viability and functional compounds, being a strategy to produce potentially probiotic dehydrated guava.

Use of maltodextrin, sweet potato flour, pectin and gelatin as wall material for microencapsulating Lactiplantibacillus plantarum by spray drying: Thermal resistance, in vitro release behavior, storage stability and physicochemical properties.

Different plant products and co-products have been studied as wall materials for the microencapsulation of probiotics due to the need for new lost-cost, abundant, and natural materials. In this study, microparticles were developed by spray drying using different combinations of conventional materials such as maltodextrin, pectin, gelatin, and agar-agar with unconventional materials such as sweet potato flour to microencapsulate Lactiplantibacillus plantarum. The microparticles obtained were evaluated for encapsulation efficiency, thermal resistance, and rupture test. The most resistant microparticles were characterized and evaluated for probiotic viability during storage and survival to in vitro gastrointestinal conditions. Microparticles A (10 % maltodextrin, 5 % sweet potato flour, and 1 % pectin) and B (10 % maltodextrin, 4 % sweet potato flour, and 2 % gelatin) showed high thermal resistance (>59 %) and survival in acidic conditions (>80 %). L. plantarum in microparticles A and B remained viable with counts > 6 log CFU.g-1 for 45 days at 8 °C and -18 °C and resisted in vitro gastrointestinal conditions after processing with counts of 8.38 and 9.10 log CFU.g-1, respectively. Therefore, the selected microparticles have great potential for application in different products in the food industry, as they promote the protection and distribution of probiotic microorganisms.