RESUMEN
In this study, tiger nut was pretreated with xylanase (Xyl), microwave radiation (MW), and a combination of both (MW + Xyl). The structure, nutritional composition, technofunctional, and antioxidant properties of the pretreated and untreated (control) tiger nut flour (TNF) were investigated. The Fourier transform infrared spectroscopic and X-ray diffractrometric spectra of the control and the pretreated samples are similar; however, there was a slight change in some peaks in the pretreated samples, indicating structural re-organization of macromolecules. Scanning electron microscopic images show reductions of surface erosion and formation of clusters in the MW + Xyl-treated TNF compared to the other pretreated samples. Pretreatment increased the protein, Ca, total phenolic content, and swelling capacity of TNF by 3.71-7.31%, 29.41-32.35%, 4.39-9.65%, and 1.59-6.75%, respectively. Meanwhile, 45.52-58.78% and 11.54-15.38% reductions in fat content and water absorption capacity, respectively, were recorded. Pretreatment of TNF with Xyl and MW + Xyl increased its soluble dietary fiber by 26.84% and 64.34%, respectively; however, a 3.31% reduction was recorded following MW treatment. The highest 2, 2-diphenyl-1-picrylhydrazyl scavenging activity (53.20%) was recorded in the MW + Xyl-treated TNF. These findings proved that pretreating TNF with microwave radiation and Xyl could improve its technological and nutritional qualities, enhancing its applicability in food systems.
RESUMEN
This study investigated the viability of encapsulated and un-encapsulated (free cell) Lactobacillus rhamnosus GG (LGG) in bread baked at different baking conditions (180 °C for 30 min, 220 °C for 20 min, and 250 °C for 15 min) and in simulated gastrointestinal conditions. The cell was encapsulated either with sodium alginate, singly or in combination with chitosan, cassava starch, and hi-maize resistant starch. There was complete loss of viability of un-encapsulated LGG after baking. Significantly (P < 0.05) higher viability was recorded for LGG encapsulated with sodium alginate + cassava starch + chitosan beads (SCCB) and sodium alginate + hi-maize resistant starch + chitosan beads (SHCB) compared to sodium alginate beads (SAB) and sodium alginate + cassava starch beads (SSB). Lactobacillus rhamnosus GG encapsulated with SHCB gave the highest viability (P < 0.05) after subjection to simulated gastric and intestinal juices. The incorporation of LGG did not have significant (P < 0.05) influence on volume, specific volume, moisture, ash, fat, and fiber contents of bread. The lowest moisture content was obtained at baking condition of 180 °C for 30 min, while the highest value was at 250 °C for 15 min. Baking condition did not cause significant (P > 0.05) change in fat, ash, and carbohydrate content of bread. The encapsulation of LGG with multiple layers of encapsulating materials significantly preserved its viability during baking and in simulated gastrointestinal conditions.
