Made available in DSpace on 2014-10-09T12:51:24Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:59:12Z (GMT). No. of bitstreams: 0 / Carragenanas, agaranas e alginatos são hidrocolóides largamente utilizados em todo tipo de produtos alimentícios como aditivos espessantes. Eles não são absorvidos pelo organismo e, portanto não introduzem calorias extras na dieta. A irradiação se apresenta com grande potencial como um método alternativo na preservação de alimentos pois não induz aumento da temperatura, e é, portanto, de grande eficácia na descontaminação de ingredientes alimentícios sensíveis ao calor. Neste trabalho, soluções dos hidrocolóides agararana, carragenana e aiginato de sódio, foram irradiadas com diferentes doses (0-10 kGy) de radiação gama de Co-60 na presença de antioxidantes também utilizados na indústria alimentícia: ácido ascórbico, extrato vegetal de rosela (Híbiscus sabdariffa L.) e isofiavona de soja. As soluções dos polissacarídeos comestíveis agarana, carragenana e alginato de sódio mostraram ser bons sistemas para avaliar o efeito da radiação ionizante por apresentarem radiossensibilidade característica medida pelas mudanças na viscosidade. Os resultados obtidos mostram que esses antioxidantes apresentam, no geral, ação radioprotetora o que pode ser de grande valia nas aplicações futuras da irradiação de alimentos em escala comercial. / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Made available in DSpace on 2014-10-09T12:50:08Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:02:41Z (GMT). No. of bitstreams: 1 10561.pdf: 1935545 bytes, checksum: bb12d76fceb74dae301ec8a8ff27eec8 (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Whilst there is a tradition of indigenous opaque sorghum beer production in Africa, the manufacture of Western-style clarified lager beers from sorghum is a relatively recent development, originating in late 1980’s Nigeria. There remains substantial scope to optimise the process by tailoring the equipment and conditions utilised more specifically to the raw material. This was the context to the main objectives of this PhD project: towards an improved sorghum brewing process. Two principal approaches were employed: 1. The reduction of primary energy usage by developing novel modifications to the mashing and wort boiling unit operations and 2. Characterisation of the material properties of a substantial co-product of sorghum brewing, sorghum spent grains (SSG) as a pre-requisite to assessing its suitability for the production of value-added products and/or biofuel. The gross chemical composition of five SSG samples sourced from commercial breweries in Africa were determined, with the sum of individual components accounting for 97.8 % material on a dry weight basis (d.b.; average value). The SSG samples contained relatively high amounts of protein (>38.0 %) as compared to values quoted for brewers’ spent grains. SSG samples were found to contain considerable amounts of residual starch (>4.55 %; d.b.), which suggested that the practice for milling and mashing with unmalted sorghum, in the breweries from which samples were sourced, could be further optimised. By boiling at reduced temperature, required energy input is reduced as the latent heat of evaporation is not provided. In Chapter 3, the impact of reduced temperature boiling on the formation and stripping of key wort volatile compounds was evaluated at both industrial scale and pilot scales (10 hL). As compared to control boiling (3.5 % evaporation), the stripping efficiency of simmer boiling (0 % evaporation) was reduced for some volatiles, including: hexanal, linalool, and β-myrcene. One key lager flavour volatile, dimethyl sulphide (DMS), displayed similar patterns of stripping when comparing simmer and control boils. In Chapter 4, we report the evaluation of a novel wort boiling technology in production-scale trials at a brewery in Ghana. The ‘PDX’ wort boiler utilises direct steam injection into wort and claims improved efficiency of heat transfer and volatile stripping. The present work demonstrated that steam injection technology could provide an approximate 50 % reduction in energy input during the boil, without significant deleterious effects on final product quality. Finished beverages produced using steam injection technology were determined to be within brand specifications by a trained sensory panel. Chapters 5 and 6 report investigations aimed at reducing the energy input when mashing with unmalted sorghum and developing knowledge of how the structure and composition of different sorghum cultivars interacts with the mashing conditions employed. Designed experimentation was used to investigate the impact of mash conditions on a novel low-temperature mashing system and a high-temperature enzyme mashing system. The reduced energy, low-temperature system was comparable to the high-temperature system in terms of extract and FAN yield, when mashing with unmalted Sorghum bicolor cv. Fara Fara. Furthermore, both enzyme systems were able to produce acceptable wort using agricultural sorghum varieties, providing that the starch properties were similar to brewing cultivars in terms of their pasting characteristics and grain hardness. Poor mashing properties were associated with cultivars displaying increased physical interaction of endosperm protein with starch, resulting in reduced starch swelling during mashing.

Please read the abstract in the section 00front of this document Copyright 1997, University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. Please cite as follows: Beta, T 1997, Processing of polyphenol-rich sorghums for food, PhD thesis, University of Pretoria, Pretoria, viewed yymmdd < http://upetd.up.ac.za/thesis/available/etd-08032007-125938 / > / Thesis (PhD (Food Science))--University of Pretoria, 2007. / Food Science / unrestricted

Flashblast™ (a registered trademark) is an intense broad spectrum pulsed light source developed by Maxwell Laboratories, San Diego, California which utilizes a Xenon flashlamp for emitting a mixed spectrum of ultraviolet, visible and infrared light. The project's objective was to determine the feasibility of ultra-high intensity light for improving food quality by reducing surface microbial contamination and selected mold metabolites (aflatoxins). Flashblast™ light was found to be highly effective in inactivating vegetative cells of E. coli, S. aureus, B. cereus and B. subtilis. Bacilli and A. niger spores were also susceptible to Flashblast light at somewhat higher fluences. Ultrastructural study with the scanning and transmission electron microscopes indicated that Flashblast™ treated gram-negative E. coli population is more susceptible to membrane damage when compared to other microorganisms. This suggests that photoinactivation involves effects on sensitive sites (genetic material) within the treated organisms which do not lead to significant changes in the microorganism morphology. Food acceptability studies on cheese, bread, strawberries and turkey breasts did not show a significant alteration in color, flavor and texture (p≤0.05). The results obtained with bread and strawberries showed commercial feasibility with an approximate 50% shelf-life extension. Flashblast™ treatment caused photodegradation of most aflatoxin types when multiple flash sequences were employed. It was concluded that full spectrum Flashblast™ light is highly effective for the inactivation of microorganisms and destruction of aflatoxins without causing undesirable sensory changes in foods. / Master of Science

Thesis (M.S.)--California Polytechnic State University, 2009. / Mode of access: Internet. Title from PDF title page; viewed on Jan. 7, 2010. Major professor: Dr. Sean Hurley. "Presented to the faculty of California Polytechnic State University, San Luis Obispo." "In partial fulfillment of the requirements for the degree of Master of Science in Agribusiness." "December 2009." Includes bibliographical references (p. 75-77).

<div> <p>Thermal processing is a critical step in shelf-stable food manufacturing to the ensure safety of the food products. To accurately model and establish the thermal processes, temperature-dependent thermal properties are needed. Existing methods for measuring the temperature-dependent thermal diffusivity (α), thermal conductivity (k) and volumetric heat capacity (C) are time consuming, tend to have high errors, and cannot provide results in a single experiment, especially at temperatures above 100°C. A novel bench scale device, named Thermal Properties Cell (TPCell), was custom made to rapidly estimate the temperature-dependent thermal parameters of food products. </p> <p> </p> <p>The TPCell used thin film heaters as the heating elements. The first study focused on estimating the thermal properties of a thin film heater. Using mathematical modeling and sequential parameter estimation, the effective thermal diffusivity of the thin film heater was found at different temperatures. The estimated thermal properties of the thin film heater were used for the second study.</p> <p> </p> <p>The objective of the second study was to design optimal complementary experiments using TPCell. Complementary experiments are a combination of experiments that enable estimation of multiple thermal parameters from the experimental temperature data, based on sensitivity analysis. Sensitivity coefficients indicate the extent of change in a measured variable due to a change in value of an input parameter. Designs of experiments were simulated and their impact on sensitivity and optimality criteria was analyzed. Results from the simulated profiles were validated using sweet potato puree. </p> <p> </p> <p>Learnings from this work can be directly applied for the optimization of all types of food thermal processes, including retort and aseptic processing. Optimally designed processes increase preservation of the heat labile nutrients, color, flavor, and taste compounds, thereby enhancing the quality of food products.</p> </div> <br>

New food processing technologies are needed to create safe, high-quality food products that are still considered "fresh" by consumers. Despite the numerous benefits attributed to 'food processing', consumers continue to perceive the term negatively. Consumer acceptance of foods processed with different technologies generally increases when factual information is provided to the consumer. Educators working within Cooperative Extension are a resource for public dissemination of food information. By working directly in the community, Extension educators often cultivate positive relationships with local clientele. Therefore, Extension educators can dispel myths related to food processing technologies and deliver science-supported information to the general public. Consumer knowledge, perceptions, and purchasing intentions associated with both conventional and emerging food processing technologies were assessed through a nationwide telephone survey administered by Virginia Tech's Center for Survey Research Center. A similar version of the telephone survey was disseminated in an online format to Virginia Extension agents. An additional section of the online survey served as a needs assessment for educational materials related to food processing technologies. A grounded theory methodology was used for qualitative coding in both surveys. Approximately 67% of consumers expressed concerns towards the term "processed foods." The majority of Extension agents (67.4%) expressed concerns about foods that had been processed, citing additional ingredients, preservatives, and additives; safety; and health implications. Both the consumer and Extension agent groups were more likely to be supportive of light-exposed foods to enhance food safety and quality, in comparison to gas-exposed foods. Although agents may be familiar with some food processing technologies, they may not have the resources to understand the scientific mechanisms for which a technology is able to increase food safety. Consumer education regarding emerging technologies is necessary to anticipate potential consumer concerns; however, agents still lack resources and information about existing and frequently used food processing technologies. Educational interventions are needed to provide information to consumers and increase their acceptance of new and currently used processing technologies so that the food industry can effectively target emerging issues related to food. / Doctor of Philosophy

The removal of yeast biomass (cropping) at the end of fermentation to inoculate a subsequent fermentation (serial-repitching) is common practice in the brewing industry. Between successive fermentations cropped yeast is stored as a slurry in cooled storage vessels under anaerobic conditions until required for subsequent use. Maintenance of yeast quality during storage is critical for subsequent fermentation performance. An assumption is made in brewing that all strains benefit from storage at 3-4°C. To test this assumption a model working system was initially established to assess cooling times of lager yeast in different suspension media. Preliminary investigations focussing on freshly propagated yeast slurry demonstrated that whilst the deleterious effects of extremely high storage temperatures on lager brewing yeast physiology was in line with expectation, utilization of traditionally recommended storage temperatures does not necessarily benefit yeast physiology when compared to slurry maintenance at slightly higher temperatures. Genome-scale transcriptional analysis in slurries cropped following an initial fermentation suggested that lager yeast might experience cold stress during slurry maintenance at typically recommended storage temperatures. In contrast, maintenance of lager yeast at a slightly higher storage temperature, in this case 10°C, yielded no adverse impact on key indicators of brewing yeast physiological state or on subsequent fermentation profiles following repitching into fermentations. Whilst these observations were not made using full production scale, they do indicate that optimal storage may not be currently being deployed for brewing yeast at full scale.

The impact of energy drinks and their ingredients on cognitive functioning has been of considerable scientific interest in recent years; however studies investigating cognitive effects of energy drink consumption have centred on the postprandial impact, that is the influence of their ingredients once absorbed into the blood. It is possible however, that sensory perception of these drinks, or their ingredients can influence cognition. The four studies outlined in this thesis aim to examine the influences of sensory perception of energy drinks in human volunteers and compare these with the effects observed in the postprandial period on a range of cognitive tasks. Postprandially energy drink treatments were observed to reduce reaction times and improve accuracy compared with a placebo control in a saccadic peripheral conflict task when a 200ms gap was present between a pre-stimulus cue and the stimulus; however when this gap was absent accuracy decreased, suggesting treatment had affected information processing and decision making processes. Sensory perception of a non-carbonated energy drink was observed to improve reaction time and accuracy in a manual choice reaction time task irrespective of gap presence, however an artificially sweetened placebo energy drink had similar effects, but only when the pre-stimulus gap was present. This thesis demonstrates that energy drinks can influence behavioural performance not only by increasing plasma glucose and caffeine levels in the postprandial period, but also through chemosensory perception, an effect elicited by the reward value of taste and flavour perception which is perhaps related to the calorific content of carbohydrates.