Browsing by Subject "Processing"
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Item Impact of Thermal Processing on Taste Development in Food(2016-06) Zhang, LiyunDespite the increasing demand, healthier foods suffer from lower consumer acceptability due to inferior flavor quality. The flavor of food is greatly affected by the food composition and thermal processing. This study specifically investigates the thermal processing impact on the positive and negative taste attributes of foodstuffs, which enables the optimization of processing strategies to improve the palatability and ultimately the consumption of ‘healthier’ formulated food products. The overall goal of this work was to characterize the effect of thermal processing on the taste-active compounds or the generation of taste modulating compounds in foodstuffs. This work mainly focuses on the influence of three common thermal processing techniques on the resulting taste profiles in three food systems respectively: the roasting of cocoa, the extrusion of corn cereal, and the frying of potato chips. These three processing techniques are widely utilized by the food industry. Bitterness was investigated in roasted cocoa and extruded whole grain corn while umami was characterized in deep fried potato chips. The influence of roasting on the taste attributes of cocoa was studied first. Roasting processes involve the Maillard reaction, which is a ubiquitous thermally catalyzed chemical pathway that is well-known to impact aroma development as well as taste, such as bitterness. Bitterness is a challenge for consumer acceptability, which is typically masked by adding sugar. The goal of this part of the research was to discover the impact of Maillard chemistry on endogenous bitter-tasting compound, catechin, in raw cocoa, and likewise on the resulting bitter taste profile of the roasted beans. Catechin-Maillard reaction products were identified by stable isotope labeling techniques in model reactions using the simulated cocoa roasting conditions. Eight reaction products were identified and reported for the first time. One of the newly-identified compounds significantly suppressed the perceived bitter intensity of the caffeine solution, which is a novel bitter blocker. Further analysis revealed that this bitter blocking compound was present in both the raw and roasted cocoa beans; however its concentration was higher in roasted cocoa beans. A generation mechanism of the bitter blocker was proposed. The results of the first phase indicated that the bitter profile of cocoa beans was altered by thermal reactions of the endogenous bitter compounds. In the second research phase of this study, the influence of extrusion on the taste profile of puffed whole grain corn products was examined. The goal of this phase is to identify the key bitter compounds and understand how they are influenced by extrusion. Three phenolic compounds (chaenorpine, coumaryl-spermidine, terrestribisamide) and one amino acid (L-tryptophan) were identified as the main bitter compounds in the extruded whole grain corn product. Based on sensory recombination analysis, chaenorpine was found to have the highest contribution to the bitterness intensity, based on the concentration of the bitter compounds reported in the saliva during mastication. Additionally, all of the identified bitter compounds were found to be degraded during extrusion, suggesting that the further optimization of extrusion could be utilized to suppress bitterness in order to improve the flavor quality of whole grain extruded products. In the last phase of this research project, the role of the thermal process, deep frying, on the taste profile of potato chips was examined. Potato chips are a highly desired food product and the umami taste is well known to positively contribute to the taste profile. Initial analysis indicated that the umami taste attribute of potato chips increases with frying time thus the compounds that contribute to umami were characterized. A dehydration product of monosodium glutamate (MSG), monosodium L-pyroglutamate (L-MSpG) and monosodium D-pyroglutamate (D-MSpG) were identified for the first time as umami enhancing compounds that contributed to the umami flavor of potato chips. The generation of pyroglutamates was reported to be directly related to the frying time. Sensory time-intensity taste analysis of potato chips with topical added L-MSpG and D-MSpG revealed significantly higher umami intensity and the overall higher potato chip flavor intensity. In summary, the impact of three thermal processes on taste profile was studied in three different food products. This study provides a novel basis for flavor optimization by investigating the thermal impact on taste chemistry. The ultimate goal of this study is to increase the market demand for health conscious foods, thus benefiting the food industry as well as promoting a healthy lifestyle.Item Improving the functionality and bioactivity of wheat bran.(2012-04) Petrofsky, Keith EricWheat bran, including the aleurone layer, contains the vast majority of phenolic antioxidants found in the wheat kernel. Unfortunately, about 80% of phenolic acids in wheat bran are structurally bound and insoluble. These bound phenolics are neither bioactive nor bioavailable during digestion. Additionally, wheat bran contains 43% total dietary fiber, but only 3% soluble dietary fiber. Insoluble fiber is less functional than soluble fiber which has been shown to lower cholesterol and regulate blood sugar. We hypothesized that processing could improve the functionality of wheat bran and bioavailability of phytochemicals in the bran. Specifically, we aimed to maximize the physical properties of viscosity and water hydration capacity in wheat bran, while also maximizing the release of bound phenolic antioxidants from the bran. Wheat bran processing included physical treatments of dry grinding, high shear mixing, high pressure homogenization (HPH), and alkali chemical treatments with different concentration, time, and temperature. Sample analysis included particle size, Wheat bran, including the aleurone layer, contains the vast majority of phenolic antioxidants found in the wheat kernel. Unfortunately, about 80% of phenolic acids in wheat bran are structurally bound and insoluble. These bound phenolics are neither bioactive nor bioavailable during digestion. Additionally, wheat bran contains 43% total dietary fiber, but only 3% soluble dietary fiber. Insoluble fiber is less functional than soluble fiber which has been shown to lower cholesterol and regulate blood sugar. We hypothesized that processing could improve the functionality of wheat bran and bioavailability of phytochemicals in the bran. Specifically, we aimed to maximize the physical properties of viscosity and water hydration capacity in wheat bran, while also maximizing the release of bound phenolic antioxidants from the bran. Wheat bran processing included physical treatments of dry grinding, high shear mixing, high pressure homogenization (HPH), and alkali chemical treatments with different concentration, time, and temperature. Sample analysis included particle size, viscosity, water hydration capacity (WHC), water extractable material (Wa-Ex), free phenolics, and visual imaging by scanning electron microscopy (SEM). Prescreening results showed that while HPH helped reduce particle size of bran regardless of treatment, only alkali chemical treatments released the vast majority of bound phenolics. Alkali treatments also contributed to viscosity increase, with interaction of variables of alkali concentration, treatment time, and temperature. Variables for optimization studies included bran grind, alkali concentration, reaction time, and reaction temperature, while process treatments that remained constant were high shear mixing after chemical pretreatment and HPH conditions. Two factorial designs were conducted to optimize viscosity and WHC of bran while maximizing release of bound phenolics. The second factorial design was an augmentation to the first and data was combined for statistical analysis. Viscosity maximum was reached using 0.5mm screen size in bran dry grinding and chemical treatment conditions of 60°C soak temp, 24 hour soak time, 0.1N NaOH concentration. WHC maximum was reached using 0.5mm screen size in bran dry grinding and chemical treatment conditions of 48°C soak temp, 20 hour soak time, 0.7N NaOH concentration. Overall, process optimization was successful and produced wheat bran with a 500% increase in viscosity, 200% increase in WHC, 500% increase in soluble fiber, and a 300 fold increase in free and soluble bound phenolic antioxidants. Visual confirmation by SEM validated analysis results and showed the optimized bran had a very open and porous structure due to the chemical weakening of the alkali treatment and high shear pulverization of the HPH treatment. The optimized viscosity process was scaled up to produce a large quantity of samples for further research in this collaborative study. Work to separate or concentrate the soluble fraction of processed bran utilized centrifugation to produce additional samples of more soluble and more insoluble processed bran fractions.Item Malonyl- conjugates of isoflavones: structure, bioavailability and chemical modifications during processing(2013-09) Yerramsetty, VamsidharSoy isoflavones are often associated with prevention of cancer, cardiovascular diseases, osteoporosis, and postmenopausal symptoms. However, the demonstration of theses physiological effects is highly inconsistent. Not all soy foods deliver the same isoflavone-associated benefits. Inconsistency in isoflavone research is partly attributed to the inadequate profiling of isoflavones, lack of standardization of the source of isoflavones, and lack of standard analytical methods for profiling and quantifying isoflavones present in different soy matrices. We are convinced that inconsistent results are due to differences in the bioavailability of the different isoflavone forms consumed. Since isoflavones in soy foods differ in their forms (e.g. conjugated and non-conjugated), large differences may exist in their bioavailability. Therefore, it is crucial to adequately profile the administered isoflavones and study the effect of their conjugation on their bioavailability. Additionally, isomerization of different isoflavone forms occurs upon thermal processing. Complete structural elucidation of the isomers and determination of their thermal stability in soy systems are important for understanding their physiological relevance. Therefore, the overall objective of this study was to determine effect of processing on the chemical modifications of isoflavones and to detect all biologically relevant forms, together with providing adequate and reliable bioavailability data for each of the most abundant isoflavone forms. Isoflavones were extracted from soy grits and were separated and isolated using semi-preparative liquid chromatography. Identification of the different isoflavones forms and isomers was accomplished based on UV wave scan, mass spectrometry, and nuclear magnetic resonance (NMR) analysis. Effect of thermal processing on isomer stability was determined by subjecting soymilk to thermal treatment at 100°C for time intervals ranging from 1 to 60 min. A rapid analytical procedure was developed to quantify isoflavones in biological fluids using stable isotope dilution mass spectrometry (SID-LCMS). Two novel isotopically labeled (SIL) analogues of natural SERMs, genistein and daidzein were synthesized using a H/D exchange reaction mechanism. Computational chemistry coupled with MS and NMR data confirmed the site and mechanism of deuteration. The developed method was sensitive, selective, precise and accurate. Bioavailability of malonylglucosides and their respective non-conjugated glucosides was determined in a model rat system. Rats were gavaged with an assigned isoflavone form. Blood and urine samples were collected at different time intervals. Different isoflavone metabolites in plasma were determined using the developed SID-LCMS method. Bioavailability was determined by calculating pharmokinetic parameters, assuming first order disposition kinetics. NMR characterization of the malonylglucoside isomers revealed its structure to be 4"-O-malonylglucosides, suggesting a malonyl migration from the glucose-6-position to the glucose-4-position. The malonylgenistin isomer represented 6-9 % of the total calculated genistein content in soymilk heated at 100°C for various periods of time. Based on rat peak plasma and urine levels and area under the curve (AUC) of the aglycone post ingestion of the respective isoflavones, it was quite evident that the malonylglucosides were significantly (P ≤ 0.05) less bioavailable than their non-conjugated counterparts. The present work provided full elucidation of the chemical structure of malonylglucoside isomers. We demonstrated for the first time that the formation of the malonylisomers is governed by thermal processing time in a soymilk system. Disregarding the isomer formation upon heating can result in overestimation of loss in total isoflavone content and misinterpretation of the biological contributions. Additionally, this work provided a validated analytical SID-LC/MS method to detect natural and known synthetic selective estrogen receptor modulators (SERMs) in a single analytical assay. Finally, this work differentiated for the first time the bioavailability of malonylglucosides as compared to their non-conjugated counterparts. The observed differences explained to a significant extent the controversy in isoflavone research. We believe that the results of this work will help streamline the experimental approach undertaken by various researchers to achieve consistent clinical conclusions and to optimize the processing parameters that result in the most bioavailable isoflavone profile, thus maximizing their health benefits.Item Mind over media: Conscious and unconscious responses to media messages(2012-09) Brehe, Stephanie KathrynHuman response to media images is a product of both conscious and preconscious processing, involving structural mechanisms within the brain as well as individual self-concepts, issues of identity, ideological beliefs, and relevance. Visual and auditory processing incorporates both conscious and preconscious mechanisms, which influence reception and integration of incoming data. Depending upon the goals or physiological cues relevant to the subject, specific data are absorbed from the media and passed on to the higher cognitive functions in the brain. Once in the conscious mind, attitudes from the conscious and unconscious may further filter incoming data. The remaining concepts and information are used as a platform for action and response in social situations. The resulting ideological platform also informs the pre-conscious mechanisms, creating a constantly evolving cycle of relevant information filtering. Recommendations are provided for a methodological approach to media research that incorporates cognitive function, identity, and ideological platforms. Key words: Media, processing, conscious, pre-conscious, ideology, identity, social cognition.Item Minnesota Taconite Workers Health Study: Environmental Study of Airborne Particulate Matter in Mesabi Iron Range Communities and Taconite Processing Plants - Taconite Processing Facilities Particulate Matter Collection and Gravimetric Analysis(University of Minnesota Duluth, 2019-12) Monson Geerts, Stephen D; Hudak, George J; Marple, Virgil; Lundgren, Dale; Zanko, Lawrence M; Olson, BernardThe Minnesota Taconite Workers Health Study (MTWHS) was initiated in 2008 and included a multicomponent study to further understand taconite worker health issues on the Mesabi Iron Range (MIR) in northeastern Minnesota. Approximately $4.9 million funding was provided by the Minnesota Legislature to conduct five separate studies related to this initiative, including: An Occupational Exposure Assessment, conducted by the University of Minnesota School of Public Health (SPH); A Mortality (Cause of Death) study, conducted by the University of Minnesota SPH; Incidence studies, conducted by the University of Minnesota SPH; A Respiratory Survey of Taconite Workers and Spouses, conducted by the University of Minnesota SPH; and An Environmental Study of Airborne Particulate Matter, conducted by the Natural Resources Research Institute (NRRI) at the University of Minnesota Duluth (UMD). NRRI’s “Environmental Study of Airborne Particulate Matter” comprises a multi-faceted characterization of size-fractionated airborne particulate matter (PM) from MIR community “rooftop” locations, background sites, and all taconite processing facilities active between 2008 and 2014. Characterization includes gravimetric determinations, chemical characterization, mineralogical characterization, and morphological characterization. This report specifically discusses the methods and gravimetric results of multiple aerosol PM sample collections from active (operating) and inactive (temporarily, but completely, shut down) taconite plants on the MIR. Taconite plant samples were collected in 2009 and 2010.