Dipeptidyl peptidase-4 (DPP-4) inhibitory activity and glucagon-like peptide (GLP-1) secretion in arsenically safe pigmented red rice (Oryza sativa L.) and its product.

Inhibition of DPP-4 and stimulation of GLP-1 secretion are therapeutic strategies for controlling glycaemia in type 2 diabetes. The present study assessed the DPP-4 inhibitory activity and GLP-1 secretory action of pigmented and non-pigmented rice (Oryza sativa L.), along with an extruded food product. Cereal-based extruded food products, with or without passion fruit powder, were prepared from red rice using a twin extruder. Optimal extrusion conditions were determined using a CCD of response surface methodology resulting in optimal conditions to be 97.5 °C, a screw speed of 250 rpm, feed moisture of 25.2% and addition of 11.25% passion fruit powder. Samples were sequentially extracted in n-hexane, ethanol (50%) and water. Ethanol/water (50:50) extracts of rice bran significantly inhibited DPP-4 activity by 70.48 ± 1.06%, comparing favourably with RR (42.55 ± 0.84%), PRR (35.91 ± 1.27%) and PA (29.14 ± 1.23%). DPP-4 inhibitory activity was retained in both extruded products albeit at reduced levels. GLP-1 secretion was stimulated mostly by extruded products extracted with n-hexane or ethanol which upregulated basal secretion by 6.1-fold and 4.2-fold, respectively. ICP-MS results showed that extruded food items have a lower arsenic content. In conclusion, there are potential opportunities for the nutraceuticals and functional food products using pigmented red rice. Supplementary Information: The online version contains supplementary material available at 10.1007/s13197-022-05444-x.

Physicochemical and phytochemical properties of foam mat dried passion fruit (Passiflora edulis Sims) powder and comparison with fruit pulp.

The aim of the present study was to develop purple passion fruit powder using the foam mat dried process. The possible effect of whipping time, methylcellulose concentration, and drying temperature on physicochemical and phytochemical properties of foam mat dried passion fruit was evaluated and compared with fruit pulp. The drying process was optimized using central composite design and optimum conditions were whipping time 2.78 min, methylcellulose 2.58%, temperature 44.05 °C. At the optimum condition vitamin C, total phenolic compound and hygroscopicity were 34.67 mg/100 g, 258.12 mg GAE/100 g, and 21.12%, respectively. The artificial neural network was applied to predict experimental outcomes. The phytochemical properties in terms of (±)-α tocopherol, D-α-tocotrienol, ß-carotene, and phenolic acid were determined using RP-HPLC. The foam mate dried powder contained a higher amount of ß-carotene (13.26 mg/100 g), total phenolic compound (258.12 mg/100 g) and phenolic acids than fruit pulp whereas fruit pulp was contented higher amount of (±)-α tocopherol (171.1 mg/100 g) and D-α-tocotrienol (27.19 mg/100 g). The study manifested foam mate drying as an effective way to develop passion fruit powder.

Effect of extrusion conditions on the physicochemical and phytochemical properties of red rice and passion fruit powder based extrudates.

The passion fruit powder blended rice flour based extrudate was developed and investigated in terms of physicochemical and phytochemical properties. The extrusion process was performed using a twin screw extruder and optimized using rotatable central composite design followed by response surface methodology. The effect of process parameters such as temperature (80-150 °C), screw speed (200-400 rpm), moisture content (20-30%) and passion fruit powder (0-15%) on product quality was investigated. The optimum extrusion conditions of temperature, screw speed, feed moisture content, and passion fruit powder were 97.50 °C, 250 rpm, 25.20% and 11.25%, respectively. At optimum condition, the predicted values of responses were expansion ratio 8.05, water absorption index 2.77, total phenolic content 129.492 mg GAE/100 g and DPPH scavenging activity 65.79%. A comparison between optimized and control extrudates revealed that thermal, crystallinity and morphological properties of extrudates differed significantly. The comparison was also conducted in terms of FT-IR, SEM-EDS and HPLC analysis. The phytochemical properties showed that ß-carotene, cyanidin-3-glucoside, peonidin-3-D-glucoside chloride were higher in control whereas the optimized sample evinced more (±)-α-tocopherol and D-α-tocopherol.

Effect of alcohol-acid modification on physicochemical, rheological and morphological properties of glutinous rice starch.

In the present study chemical modification of glutinous rice starch was carried out using 1-Buatnol-hydrochloric acid with varying time and temperature. The changes in physico-chemical, dynamic rheological and morphological properties of starch during hydrolysis was investigated. There was a significant increase in water solubility of starch due to modification; however, swelling and sedimentation value decrease after modification. The peak, hold and final viscosity of modified starches were decreased significantly as compared to native starch. Thermal properties and dynamic rheological properties of rice starch were changed with the change in time and temperature during modification. The storage (G') modulus, loss (G″) modulus, dynamic viscosity (η') and complex viscosity (η*) of modified starches were varied significantly. Analysis of microstructure revealed that the hydrolysis altered morphology of starch granules. The hydrolysis was affected the surface properties and granule size of rice starch. These results suggested that 1-butanol-HCl hydrolysis of glutinous rice starch can be a preferred way of modification.