Modelling inactivation kinetics of free and encapsulated probiotic cells in millet biscuit under different baking conditions.

The rising popularity of probiotic food in the diet for improved health benefits leads to the development of new probiotic functional foods. In general, biscuit is a long-shelf-life snack product that can be consumed straight from the pack without further processing. Although the development of probiotic bakery products is an innovative approach to market expansion, the infusion of probiotics in biscuits to produce probiotic biscuits has not been explored because of the complexity of the baking process. Therefore, this study aimed to evaluate the impact of baking conditions (160, 180, 200, and 220 °C) on the viability of free and encapsulated probiotic Lactobacillus acidophilus NCDC 016 cells by adding them into biscuit dough separately and baking for up to 600 sec. The cells were encapsulated using 20 % maltodextrin and 8.51 % gum arabic as a wall material and spray drying at an inlet and outlet air temperature of 150 and 55 ± 2 °C, respectively. At different baking temperatures (160, 180, 200, and 220 °C), the viability of probiotic (free and encapsulated) cells, the physicochemical properties of biscuits, and the inactivation kinetics of cells were examined by withdrawing samples every 120 sec. The survivability of encapsulated cells was observed to be higher than free cells at 160 and 180 °C for 600 sec. The moisture content and water activity were found to be higher and lower, respectively for encapsulated probiotic biscuits than for the biscuit containing free cells. The observed results of higher cell viability at 200 °C, 360 sec (5.38 log CFU/g) than at 180 °C, 600 sec (5.02 log CFU/g) can be explained by the time-temperature combination. Thus, producing the probiotic biscuit at baking conditions of 200 °C and 360 min is possible, providing the cell viability of 5 log CFU/g of probiotic biscuit. Further, the inactivation kinetics of cells were predicted by log-linear, Weibull, log-logistic, Gompertz, and Buchanan models. Under all baking conditions, the log-linear model was the best model for describing the data of encapsulated and free cells.

Erratum: Retraction notice to "Studies on survivability, storage stability of encapsulated spray dried probiotic powder" [Curr. Res. Food Sci. 3 (2020) 235-242].

[This corrects the article DOI: 10.1016/j.crfs.2020.09.001.].

Studies on survivability, storage stability of encapsulated spray dried probiotic powder.

Awareness about probiotic food and their health benefits is increasing tremendously. However, probiotics have to withstand the harsh conditions that come across during their processing, handling, storage, and gastrointestinal conditions. Encapsulating technologies can be used to protect the probiotics during their passage through the gastrointestinal system of the human gut. Probiotics as an ingredient in dry powder form can be easily handled, stored, and used in developing the probiotic functional products. In the present study, probiotic cells (Lactobacillus acidophilus) were encapsulated by spray drying technology to produce a probiotic powder using 20% of maltodextrin and varied concentrations of gum arabic. The effect of processing conditions such as inlet air temperature (130-150 °C) and gum arabic concentration (0-10%) on the encapsulation efficiency and physical properties were studied. Further, the free and encapsulated probiotic cells were exposed to the simulated-gastric intestinal (SGI) fluid conditions and different storage conditions for their viability. For all the tested formula, moisture content, water activity, encapsulation efficiency, hygroscopicity, and wettability obtained were in the range of 4.59-9.05% (w.b.), 0.33-0.52, 65-89.15%, 12-21.15 g H2O/100g dry weight, and 116 s-353 s, respectively. The Fourier transform infrared (FTIR) results have shown that gum arabic and maltodextrin have structural stability during spray drying. The encapsulated probiotic cells have shown a positive effect and exhibited better viability after exposure to a SGI solution at different pH levels and duration compared to free cells. The viability of encapsulated cells stored at refrigerated condition (4 °C) was found to be higher than the viability of cells stored at room temperature (25 °C).

Encapsulation of Lactobacillus acidophilus NCDC 016 cells by spray drying: characterization, survival after in vitro digestion, and storage stability.

In the present study, probiotic cells (Lactobacillus acidophilus) were encapsulated by spray drying technology to produce a probiotic powder using 20% maltodextrin and varied concentrations of gum arabic. The effects of processing conditions such as inlet air temperature (130-150 °C) and gum arabic concentration (0-10%) on the encapsulation efficiency, physical properties, and morphology were studied. For all the tested formulae, the moisture content, water activity, encapsulation efficiency, hygroscopicity, and wettability obtained were in the range of 4.59-9.05% (w.b.), 0.33-0.52, 65-89.15%, 12 to 21.15 g H2O per 100 g dry weight, and 116 s to 353 s, respectively. The Fourier transform infrared (FTIR) results have shown that gum arabic and maltodextrin show structural stability during spray drying. The encapsulated probiotic cells exhibited better viability of 4.03, 4.68, and 5.34 log CFU g-1 after 3 h of exposure to a simulated gastric fluid (SGF) solution at pH levels of 1, 1.5, and 2, respectively, compared to free cells. The viability of encapsulated cells stored for 12 weeks under refrigerated conditions (4 °C) and at room temperature (25 °C) was found to be 6.05 log CFU g-1 and 1.24 log CFU g-1, respectively.