Budaraju, Sravanthi2021-04-122021-04-122019-01https://hdl.handle.net/11299/219331University of Minnesota Ph.D. dissertation.January 2019. Major: Food Science. Advisor: Kumar Mallikarjunan. 1 computer file (PDF); xviii, 191 pages.Barley malt rootlets (BMR) are the low-value byproduct obtained after the cleaning process of malting and have been shown to contain significant amounts of antioxidant compounds. In the current study the total phenolic content (TPC) and antioxidant activity of the BMR extracts were evaluated for both free and bound phenolics using various pretreatments (autoclave, enzyme hydrolysis, steaming, microwaving and roasting) and extraction methods (conventional solvent extraction (CSE) and microwave assisted extraction (MAE)). The optimum conditions for the extraction methods were developed for maximum TPC and %DPPH activity using response surface methodology. The phenolic extracts obtained from each of the study were evaluated for their potentiality as natural antioxidants in corn oil. Among the pre-treatments, autoclaving exhibited the highest values for free phenolics of 3.8 mg. g-1 of the dry weight of BMR and 71.6% of antioxidant activity. Pre-treatments significantly increased the free phenolic content of BMR phenolic extracts but not the bound phenolic content. In CSE, the effect of solvent type (acetone, methanol, ethanol), solvent concentration (20, 50, 80%), temperature (20, 40, 60oC), time (30, 60, 90 min) and solvent volume (5, 10, 15 ml) on TPC, DPPH activity of BMR was investigated. Acetonic extracts had the highest phenolic content followed by ethanol and methanol. The maximum predicted free TPC under the optimized conditions for acetone (80%, 58.3oC, 10.5 ml, 90 min) was 3.5 mg. g-1 dw. of BMR. In MAE method, process parameters such as time (5, 10, 15 min), temperature (20, 40, 60°C) and solvent concentration (20, 50, 80%) were optimized. The optimal conditions were 5.4 min, 42.1°C and 79.1% of acetone solvent concentration for free phenolics (4.82 mg. g-1dw. of BMR) and 14.9 min, 36.5°C and 63.7% of solvent concentration for bound phenolics (2.80 mg. g-1 dw. of BMR) which were 37% and 51.2% higher than that obtained using respective optimum process conditions for CSE.enAntioxidantsBarley malt rootletsMicrowave-assisted extractionPolyphenolsResponse surface methodologySolid-liquid extractionThesis or Dissertation