Influence of fermentation followed by ultrasonication on functional properties of sorghum extrudates

Abstract

Extrusion process deals with a compromise between better texture and less nutrition.In the present study, sorghum flour was subjected to fermentation followed by ultrasonication prior to extrusion to increase the antioxidant activity (AA) and total phenolic content (TPC) in the flour. AA and TPC of the sorghum flour were increased when fermented for 12 hr and further decreased significantly with an increase in the fermentation time. During the ultrasonication, a significant diminution in AA and TPC of the flour was reported with an increment in the ultrasonication intensity and fermented flour to water ratio. No significant impact of the ultrasonication time was found on AA and TPC of the sorghum flour. Optimum AA and TPC were obtained as 178.8 μmol TE/100 g dry weight (DW) and 77.8 mg GAE/100 g DW, respectively.Extrudates obtained from the pretreated sorghum flour under optimum conditions had improved nutritional and textural qualities. Also, the pretreated sorghum flour showed low stability of starch crystallites and crystalline fraction. Practical ApplicationsMillets and sorghum possess high amounts of phenolics, polyphenols, and other bioactive compounds. It was explicated from the results that the fermentation followed by the ultrasonication could improve the antioxidant activities and phenolics in the sorghum flour. Furthermore, sorghum extrudates with remarkable retention of antioxidant activity, phenolic content, functional, and textural properties were obtained. This technology may help the food industries to develop gluten-free and healthy snacks by incorporating sorghum (underutilized cereal) into human diet.

Study of continuous flow ultrasonication to improve total phenolic content and antioxidant activity in sorghum flour and its comparison with batch ultrasonication

“…In past few years, ultrasound assisted extraction of phenolic compounds from pomegranate peel [12] , mustard [13] , carrot pomace [14] , grape pomace [15] , beans [16] , buckwheat [17] , black soybean [18] , and orange pomace [19] has been extensively investigated but use of ultrasonication to enhance the phenolics itself in food is limited [20] , [21] , [22] and is few in case of sorghum [23] , [24] . The mechanism for ultrasonic is the cavitation of bubbles upon the propagation of the acoustic waves.…”

“…Even though batch ultrasonication has been proven to be effective in extracting the phenolics in food materials, it undergoes the extraction difficulty for highly concentrated samples [21] , [24] . From the earlier research, it could be hypothesized that higher sample concentration, less intensity and less time would be required in continuous flow ultrasonication to get the TPC and AA in the sorghum flour equivalent to that of batch ultrasonication [23] , [24] . In addition to this, the influence of flow rate as an additional parameter on phenolic release in the continuous flow ultrasonication would be of interest.…”

Recent advances with cold plasma technology for millet processing: A brief review

“…Gamma irradiation, ultrasonication, ozonation, pulsed electric field, high‐pressure processing, ultraviolet light processing, pulsed light processing, and cold plasma (CP) technology are the widely known and emerging non‐thermal technologies in the food processing field for ensuring the safety and quality of the food along with aiding the secondary operations like extraction, filtration, drying, and fermentation. In recent times, the effect of these non‐thermal technologies on millet processing has also been explored for germination enhancement (Sharma et al, 2018), fungal decontamination (Huang et al, 2021), improving extrusion (Lohani & Muthukumarappan, 2020), and for molecular changes (Sharma et al, 2022). Among these non‐thermal technologies, CP is found to be one of the most feasible processes as there exists a provision to operate it under atmospheric conditions.…”

The Effects of Processing on Bioactive Compounds and Biological Activities of Sorghum Grains

“…The pericarp and the testa, which are rich in carotenoids, anthocyanins, phenolic acids, flavonoids, and tannins, are often removed for taste, causing the decrease of these bioactive compounds. Some processing technologies like germination, fermentation, and enzymolysis could increase the content of bioactive compounds or even synthesize new bioactive compounds [ 11 , 12 ]. Therefore, how the processing technologies change the bioactive compounds and the effective utilization or improvement of these processing technologies to maintain or increase the bioactive compounds need to be studied.…”