Influence of Flour and Processing Factors on Flavor Attributes of Extruded Corn Puff

Consumer awareness regarding the impact of nutrition on health and wellness has been steadily growing, along with interest in fresh, natural and wholesome foods and ingredients. Despite the growing demand for healthy food, and the increasing information supporting the contribution of whole grain products to a healthy diet consumers still fail to meet the USDA recommended daily amount. Among the major factors limiting consumption of whole grains are negative sensory attributes associated with whole grain products. When cereal foods are manufactured with whole grain instead of refined grain flour, lower product acceptability is observed.;Understanding how whole grains differ from more widely accepted refined grain flours, and the mechanisms of whole grain flavor development is a vital step in improving the food production system to meet consumer flavor expectations. To address flavor quality challenges, this work had two distinct yet, related goals ultimately aiming to improve the flavor profile of extruded whole grain products. The first aimed to characterize the key aroma differences between refined and whole grain extruded corn puffs. The second goal aimed to understand how processing can influence the content and delivery of bitter compounds from the food matrix. Both aimed at gaining insight on how ingredients and processing affect flavor development and perception thus, providing a basis for food producers to tailor extrusion processing to create more palatable wholesome products and boost consumer acceptance.;Key aroma compounds that drive the differences in the refined and whole grain extruded corn puffs were characterized to better understand the flavor performance of whole grain formulated corn puffs and related mechanistic pathways of flavor generation. Gas chromatography-olfactometry-mass spectrometry (GC-O-MS) and aroma extract dilution analysis (AEDA) were utilized to examine aroma profiles and identify key aroma differences between whole grain and refined grain extruded corn puffs. Following identification sensory descriptive analysis was performed to evaluate the impact of compounds identified through AEDA on aroma attributes of the corn puffs.;GC-O/MS and AEDA analysis identified 13 odor active compounds with different aroma intensity and quantitative concentrations between the whole grain and refined corn puffs. Of the identified aroma compounds 9 were significantly higher in concentration in the whole grain puffs (WGP), 2-methyl-pyrazine, 2,3-dimethylpyrazine, methylthiazoline, 2-ethyl-3,5-dimethylpyrazine, 3-hydroxy-2-methyl4H-pyran-4-one, 2-methoxyphenol, 2-acetyl-2-thiazoline, 2-methoxy-4-vinylphenol and 4-hydroxy-3-methoxybenzaldehyde were higher in concentration in while one compound 2,5-dimethylpyrazine was higher in concentration in refined grain puffs (RFP). Based on the chemical structures of the identified odorants three reaction pathways that drive aroma differences were identified as of interest; the Maillard or non-enzymatic, phenolic degradation and the lipid oxidation reaction pathways.;Descriptive Analysis (DA) was employed to investigate the sensory impact of the identified odorants important for aroma attribute differences. In general, the results indicated that the perceived puffed aroma intensities of the RFP and WGP profiles agreed with the quantitative analysis of the identified aroma compounds. The WG puffs were reported to have a greater intensity of cooked, corn chip, roasted and toasted attributes. Which was reflective of the higher concentration of Maillard reaction products which have aroma characteristics like roasted and toasted.;In addition to changes in the aroma attribute intensities, other flavors characteristics like taste are important. One bitter compound chaenorpine, a major contributor of bitterness in extruded WGP, was also examined. The impact of processing treatments applied to flour, addition/exclusion of ingredient aids, pH modification and flour aging, on the concentration of available chaenorpine were explored.;The influence of heat treatment on bitterness generation was examined using both a bench scale thermal processing protocol, as well as pilot scale extrusion. Chaenorpine concentration was monitored via LC/MS/MS and was determined in solvent extracts, reflecting total content as well as in saliva extracts after mastication, reflecting the oral concentration during consumption. The results indicated that addition of tri-sodium phosphate (TSP) reduced the level of chaenorpine in the puffs. The observed reduction was thought to be related to the ability of the processing aid to raise the pH of the sample. A series of pH modifications were further examined the influence of pH on chaenorpine content. The results revealed a two-fold reduction of chaenorpine when pH of the sample was in the basic region when compared to acidic.;Sensory studies agreed with analytical findings and confirmed that the overall perception of bitterness was reduced in puffs, when TSP was included in the formulation and the concentration of chaenorpine was reduced. Thus, providing a potential ingredient method that could effectively reduce bitterness perception of whole grain corn products and improve the overall flavor profile. (Abstract shortened by ProQuest.).