O desperdício de alimentos desde sua produção até o consumo, encontra-se, atualmente, no patamar de um terço de tudo o que é produzido no mundo. Durante a etapa de transporte, principalmente de alimentos com alta perecibilidade, tais como frutas e hortaliças, ocorrem perdas consideráveis devido à não utilização de tecnologia adequada de conservação e sua utilização é restrita devido ao seu alto custo. Durante o transporte refrigerado rodoviário de produtos agrícolas perecíveis, a carga transportada é suscetível à diversas aberturas de porta do caminhão refrigerado para a realização das entregas ao longo do percurso. Quando isso ocorre uma carga térmica de massa de ar entra no ambiente refrigerado elevando a temperatura neste momento, causando prejuízos em relação à qualidade do alimento transportado. Desta forma, é proposto neste trabalho uma etapa de pré-resfriamento em momento anterior à abertura das portas do caminhão refrigerado, a fim de se manter a temperatura dentro da faixa ideal de conservação. Para isso utilizou-se a estratégia do Controle PID na redução da temperatura antes da abertura de portas e após estas serem fechadas. Foi obtido um modelo em que foram simuladas aberturas de portas de um caminhão refrigerado utilizando técnicas de controle com o objetivo de manter a temperatura do ar do ambiente refrigerado dentro da faixa ideal. Os resultados obtidos indicam o potencial da utilização do controle de sistemas aliado à estratégia do pré-resfriamento na manutenção da temperatura auxiliando na preservação dos atributos de qualidade de alimentos transportados. Além disso, avalia-se que este modelo possa ser aplicado ao transporte refrigerado de outros alimentos. / Food waste, from its production up to its consumption, currently accounts for one-third of all the food produced in the world. During the transport stage, especially of highly perishable foods, such as fruit and vegetables, considerable losses occur due to not using adequate preservation technology; its use is limited owing to its high cost. Over the refrigerated road transport of perishable agricultural products, the load transported is susceptible to different door openings of the refrigerated truck for the deliveries along the route. When this occurs, an air mass thermal load enters the refrigerated environment elevating the temperature, causing damages to the quality of the food transported. Hence, this work proposes a pre-cooling stage at the moment prior to opening the doors of the refrigerated truck, so as to keep the temperature within the ideal preservation range. For this, PID Controller was employed for reducing the temperature before doors are opened and after they are closed. A model was obtained, whereby the door openings of a refrigerated truck were simulated using control techniques aiming to maintain the temperature of the refrigerated environment air within the ideal range. The results indicate the potential of using the system control combined with the pre-cooling strategy for keeping the temperature, aiding to preserve the quality attributes of the food transported. Besides, this model is believed to be able to be applied to the refrigerated transport of other foods.

O conceito de qualidade dos alimentos, na visão do consumidor, reflete a satisfação de características como sabor, aroma, aparência, embalagem e disponibilidade. Fatores econômicos e sociais como o custo e hábitos alimentares geralmente também têm influência sobre a escolha do produto. A irradiação é uma técnica eficiente na conservação dos alimentos, pois reduz as perdas naturais causadas pelos processos fisiológicos, além de eliminar ou reduzir microrganismos, parasitas e pragas, sem causar qualquer prejuízo ao alimento, tornando-os mais seguros ao consumidor; porém, pode haver aumento no custo dos alimentos. Pesquisas apontam que a praticidade é uma característica já incorporada pelo consumidor, o preço pode ser um fator de restrição à popularização do produto irradiado, embora alguns consumidores considerem que, devido ao fato de evitar desperdícios, o aumento do custo pode ser viável. O objetivo deste trabalho foi analisar o custo do uso da tecnologia de irradiação de alimentos e verificar se os consumidores, quando informados sobre as vantagens na segurança alimentar, estão dispostos a pagar por este tratamento, bem como o quanto estão dispostos a pagar. A metodologia consistiu em um estudo sobre a viabilidade econômica da implantação da tecnologia de irradiação de alimentos por meio de um levantamento sistemático da literatura especializada, com o intuito de verificar o custo de implantação e o acréscimo que o produtor terá em relação ao custo da tecnologia. Também foi realizada uma pesquisa em uma Instituição de Ensino Superior sobre a predisposição do consumidor em arcar com este custo. Os resultados do estudo indicam um acréscimo, ao produtor, que pode variar de US$ 0,01 a US$ 0,25 por quilograma e também indicam que 75% dos consumidores entrevistados aceitam pagar mais pelo alimento irradiado. A partir desses resultados, concluiu-se que quanto maior o poder aquisitivo, maior a predisposição em arcar com o acréscimo ao custo do alimento irradiado. / The concept of food quality, in the consumer point of view, reflects the satisfaction of characteristics such as flavor, aroma, appearance, packaging and availability. Economic and social factors, such as cost and eating habits, generally, also influence the choice of a product. Irradiation is an effective technique in food preservation because it reduces the losses caused by natural physiological processes, either reducing or eliminating microorganisms, parasites and pests without causing any damage to the foods and, thus, making them safer to consumers. Nevertheless, there may be an increase in the cost of foods. Research indicates that practicality is already a deep-rooted feature of consumers. The price may be a limiting factor to the popularization of the irradiated product, although some consumers consider that, due to the avoidance of waste, the increased cost may be feasible. The objective of this study was to analyze the cost of using food irradiation technology and verify (a) whether consumers, when informed of the benefits in food safety, are willing to pay for this treatment and (b) how much they are willing to pay. The methodology consisted of a study on the economic feasibility of food irradiation technology by means of a systematic survey of the literature, in order to verify the cost of this process implementation and the increase in costs for the producer. Also, a survey was conducted in an Institution of Superior Education about the consumer\'s willingness to pay for this higher price. The study results indicate a rise in costs to the producer, ranging from $ 0.01 to U.S. $ 0.25 per pound; it was also found that 75% of the consumers surveyed are willing to pay more for irradiated food. From these results it was concluded that the higher the consumption power is, the greater the willingness to afford the additional cost irradiated foods have.

No description available.

Brown and Penicillium rot (blue and green mould) are the most common postharvest diseases in New Zealand, causing significant postharvest fruit losses. Current practice uses fungicides to control the postharvest diseases; however there are perceived health risks associated with the use of such chemicals. Recently, there has been substantial interest in chemicals that are considered Generally Regarded as Safe or GRAS and natural products as alternative postharvest treatments to replace currently used fungicides. In this study, ethanol (GRAS chemical) and the natural products honey, milk and essential oils (lemon, lemongrass, manuka and orange) were assessed as potential alternative treatments to replace the currently used fungicides on both peaches and oranges. In pilot studies ethanol was applied to the fruit by either vapour or dipping (30 seconds or 1.5 minutes). Honey, milk and essential oils were applied by dipping at 30 seconds. Essential oils were also tested using a microtiter assay. Exposing fruit to ethanol vapour proved effective at inhibiting fungal growth, but impacted negatively on fruit quality. Peaches that were exposed to 70% to 100% ethanol vapour were protected against fungal infection for up to 30 days when stored at either 4ºC or room temperature. This is compared to two days for untreated peaches and three days for fungicide -treated peaches. However, the ethanol-treated peaches suffered from severe browning. In contrast, 20% ethanol protected peaches for ten days when stored at 4ºC and two days at room temperature. The fruit that were exposed to 20% ethanol did not brown as a result of the treatment. Oranges that were exposed to 20%, 50%, 70% and 100% ethanol vapour were protected from fungal inhibition for 30 days at both 4ºC and room temperature, but they too suffered from severe browning. Dipping was not as effective as vapour at protecting against fungal infection, but had a little effect on fruit quality. Peaches dipped in 20% to 100% ethanol were completely rotten by ten days when stored at room temperature, but the peaches experienced little to no browning. Untreated and fungicide-treated fruit were protected for one day and two days, respectively. Milk and honey do not appear to have potential as postharvest treatments. Peaches that were treated with 20%, 50% and 100% whole milk and 50% manuka honey showed greater degree of fungal infection compared to untreated peaches after both room temperature and 4ºC storage. At room temperature, peaches that were exposed to 20%, 50% and 100% milk were completely rotten at eight days, compared with ten days for untreated peaches. In contrast, at 4ºC, peaches that were treated with 100% milk were completely rotten at 30 days, while only a slight fungal infection observed on untreated fruit. Similar to milk, honey-treated peaches were also completely rotten at 30 days at 4ºC storage.In vitro (microtiter) assay of the essential oils showed that orange and manuka oils appeared to be effective only at high concentrations. In contrast, lemongrass and lemon oils appeared to be effective even at low concentrations. Of the essential oils tested in the in vivo assay, lemongrass and lemon oils have the greatest potential. Oranges that were exposed to 0.05% lemongrass oil, 0.25% and 0.5% lemon oil were protected for 30 days when stored at 4ºC or room temperature. They provided the best antifungal activity compared to the other concentrations of all four essential oils tested as well as fungicide treatment for 30 days. Of all the treatment tested, 0.05% lemongrass oil, 0.25% and 0.5% lemon oil appeared to be the most promising treatments. However, these treatments need to be tested for antifungal effects, fruit quality, flavour and nutritional effects in large scale experiments before they can be applied as replacements to currently used fungicides. Also, essential oils are complex compounds; therefore it would be of interest to determine the active compound(s) of the lemongrass and lemon oils.

The major objective of this project was to evaluate the feasibility of artificial neural networks (ANNs) and genetic algorithms (GAs) for modeling and optimization of food thermal processing. The specific objectives were: (1) to develop a comprehensive computer simulation program for thermal processing, (2) to apply ANNs and GAs for modeling and optimization of constant retort temperature (CRT) thermal processing and variable retort temperature (VRT) thermal processing, (3) to develop dynamic models for thermal processing using ANNs, and (4) to explore ANN-model-based analysis of critical control points for deviant thermal processes. / As a preliminary research, neural network models were successfully developed for modeling of residence time distribution (RTD) under aseptic processing conditions. The main configuration parameters of neural networks such as the number of hidden layers and their neurons, learning runs, choice of transfer functions and learning rules were optimized. / In order to provide experimental data needed for developing and testing of ANN models and GA optimization, a comprehensive finite difference computer simulation program for thermal processing was first developed in MS Visual Basic language, which could be used for simulating different thermal processes such as constant retort temperature (CRT) and variable retort temperature (VRT) thermal processing. / The second objective was focused on developing modeling and optimization methods for CRT thermal processing using ANNs and GAs. The ANN models were developed for predicting process time, average quality retention, surface cook value, final temperature difference, lethality ratio, and equivalent energy consumption. Using this optimization program, the effects of process variables on the optimal retort temperature and the maximum average quality retention were investigated. / The final part of the thesis research was focused on applying ANN methods for the analysis of critical control points (CCPs) for deviant thermal processes, one of the important steps required for developing hazard analysis of critical control points (HACCP) program. The results indicated that ANN models could be efficiently used for the analysis of CCPs of thermal processing. Such a concept can be expanded for developing an ANN based HACCP expert system for thermal processing. (Abstract shortened by UMI.)

A total of twenty-eight Bacillus spp. isolated from value-added surimi nuggets and their raw ingredients, were tested against each other and selected reference strains of Bacillus and Clostridium for their production of inhibitory substances using the deferred antagonism assay plating method. The isolated Bacillus strains showed inhibitory activity against all Bacillus strains, with the exception of the producer strain, as well as being effective against various strains of C. botulinum (type A, B and E). Subsequent studies showed that the inhibitory activity was detected in the culture supernatant in the late stationary phase of growth prior to sporulation. The inhibitory activity of two Bacillus strains (FN2A and FN33) were selected for further study. The inhibitory substances produced by these two strains were proteinaceous in nature, heat stable (100°C for 15min) and unaffected by organic solvents. A comprehensive study was conducted on the structural characterization of the inhibitor produced by B. subtilis FN2A using FPLC, FTIR, MS and MS/MS. Structural analysis of the inhibitor produced by B. subtilis FN2A showed that it was similar in structure to Surfactin. / Preliminary studies have shown that the Surfactin-like-compound from B. subtilis FN2A was produced in significant amounts during growth in bread with maximum production occurring in the late stationary phase (72h), at 30--35°C and at pH 6.5--7.0. Optimization studies on the production of the Surfactin-like-compound by B. subtilis FN2A in bread using a response surface methodology approach showed that temperature (33--36°C); autoclaving time (30 min); inoculum level (4%), alkali pre-treatment (0.16%), water activity (0.995) and pH 6.66 enhanced the production of the Surfactin-like-compound in bread. The compound produced under these optimal conditions also maintained its activity when subjected to various processing treatments (autoclaving, freezing and freeze drying). / Initial studies showed that low levels (1% w/w) of the Surfactin-like-compound inhibited the growth of B. cereus and proteolytic and non-proteolytic strains of C. botulinum in a model agar system. However, it had no effect on non-proteolytic strains of C. botulinum when bread, or methanol extracts of bread (1--20%), were added to formulated value-added sterile trout nuggets, with all nuggets being toxic after 28 days at 12°C. Furthermore, inoculation of B. subtilis FN2A directly into nuggets also failed to inhibit growth of non-proteolytic strains of C. botulinum. Omitting certain ingredients in the formulation failed to enhance the anti-botulinal effect of the bread or methanol extracts of the Surfactin-like-compound in the value-added nuggets. However, reducing the pH of the nuggets to ~5.5 enhanced the anti-botulinal effect of the Surfactin-like-compound. Further research is required to improve the dispersibility of the Surfactin-like-compound to inhibit the growth of C. botulinum in food systems.

No description available.

Recent reports detail a rise in the practice of home food preservation in the United States due to economic woes, nutritional concerns, and increasing devotion to local food production.Home food preservation is the processing of foods in order to extend its shelf-life. Current common approaches to preserving foods at home include pressure canning, freezing, drying, water bath canning, and cellaring/storing. Local food production in four Kentucky counties were examined through in-depth qualitative interviews with home food preservation practitioners to yield a rural/urban comparison. Forty home food preservation practitioners were interviewed between Fall 2009 and Fall 2013. The primary question driving this project is what motivates those who grow gardens and practice home food preservation in an era of readily available, relatively cheap foodstuffs? Secondary questions include, how do the motivations of home food preservation practitioners compare in rural and urban areas? What are the links, if any, between home food preservation and environmental sustainability concerns in rural and urban areas? Each of these questions will be examined through a mixture of qualitative methods and a grounded theoretical approach. In-depth field interviews with 40 preservers, documentary filmmaking, and participant observation were conducted in two rural and two urban Kentucky counties. Interview transcripts were coded by themes, interpreted using hermeneutic analysis, and analyzed by grounded theory. Policy institutes could make gains from this research by building upon already existing community food practices. Agriculture extension agent could use these findings to inform their food preservation programs and improve safety recommendations.

Bacteriocin leader pepides are currently receiving much attention due to their possible functions. It is predicted that these leaders prevent cytoplasmic toxicity within the producer organism by rendering the bacteriocin inactive. Leucocin A, a class IIa bacteriocin produced by Leuconostoc gelidum UAL187-22 is synthesized with a 24 amino acid leader pepide which is cleaved during extracellular translocation. The antimicrobial activity of the leucocin A precursor, pre-leucocin A, was determined to gain insight into whether, the presence of a leader peptide has an impact on anti-listerial activity. The leucocin A and pre-leucocin A genes were generated by PCR of L. gelidum UAL187-22 plasmid DNA. Recombinant plasmids, pLcaA and pPreLcaA were isolated by cloning the amplified genes into the Escherichia coli pMAL.c2 vector, and by screening transformant colonies using blue white selection methods. The malE-LcaA and malE-preLcaA fusion genes were expressed, and resulting maltose binding fusion proteins, were purified using amylose affinity chromatography. Fractions collected, contained partially pure forms of MBP-LcaA (46.433 kDa) and MBP-preLcaA (49.088 kDa) fusion proteins. Following Factor Xa digestion, the MBP affinity tag was removed; and recombinant peptides, leucocin A and pre-leucocin A were further purified by reverese phase high performance liquid chromatography. It was determined that leucocin A was eluted with a retention time of 24.893, while pre-leucocin A was eluted with a retention time of 31.447. Fractions of pure leucocin A and pre-leucocin A were thereafter assayed for activity using a deferred antagonism assay, with Listeria monocytogenes being the indicator strain. Pre-leucocin A tested positive for antimicrobial activity. However, when compared to leucocin A it was found that the leucocin A precursor inhibits Listeria to a lesser degree than leucocin A. The relative bactericidal activities of leucocin A and pre-leucocin A was calculated at 6.0 x 10⁵ AU and 4.0 x 10⁵ AU. Taking this into consideration, it was estimated that the leucocin A precursor is ~66.667 % active as mature leucocin A. Hence the presence of a leader peptide does not have an influence on leucocin A antimicrobial activity. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2008.

Brown and Penicillium rot (blue and green mould) are the most common postharvest diseases in New Zealand, causing significant postharvest fruit losses. Current practice uses fungicides to control the postharvest diseases; however there are perceived health risks associated with the use of such chemicals. Recently, there has been substantial interest in chemicals that are considered Generally Regarded as Safe or GRAS and natural products as alternative postharvest treatments to replace currently used fungicides. In this study, ethanol (GRAS chemical) and the natural products honey, milk and essential oils (lemon, lemongrass, manuka and orange) were assessed as potential alternative treatments to replace the currently used fungicides on both peaches and oranges. In pilot studies ethanol was applied to the fruit by either vapour or dipping (30 seconds or 1.5 minutes). Honey, milk and essential oils were applied by dipping at 30 seconds. Essential oils were also tested using a microtiter assay. Exposing fruit to ethanol vapour proved effective at inhibiting fungal growth, but impacted negatively on fruit quality. Peaches that were exposed to 70% to 100% ethanol vapour were protected against fungal infection for up to 30 days when stored at either 4ºC or room temperature. This is compared to two days for untreated peaches and three days for fungicide -treated peaches. However, the ethanol-treated peaches suffered from severe browning. In contrast, 20% ethanol protected peaches for ten days when stored at 4ºC and two days at room temperature. The fruit that were exposed to 20% ethanol did not brown as a result of the treatment. Oranges that were exposed to 20%, 50%, 70% and 100% ethanol vapour were protected from fungal inhibition for 30 days at both 4ºC and room temperature, but they too suffered from severe browning. Dipping was not as effective as vapour at protecting against fungal infection, but had a little effect on fruit quality. Peaches dipped in 20% to 100% ethanol were completely rotten by ten days when stored at room temperature, but the peaches experienced little to no browning. Untreated and fungicide-treated fruit were protected for one day and two days, respectively. Milk and honey do not appear to have potential as postharvest treatments. Peaches that were treated with 20%, 50% and 100% whole milk and 50% manuka honey showed greater degree of fungal infection compared to untreated peaches after both room temperature and 4ºC storage. At room temperature, peaches that were exposed to 20%, 50% and 100% milk were completely rotten at eight days, compared with ten days for untreated peaches. In contrast, at 4ºC, peaches that were treated with 100% milk were completely rotten at 30 days, while only a slight fungal infection observed on untreated fruit. Similar to milk, honey-treated peaches were also completely rotten at 30 days at 4ºC storage.In vitro (microtiter) assay of the essential oils showed that orange and manuka oils appeared to be effective only at high concentrations. In contrast, lemongrass and lemon oils appeared to be effective even at low concentrations. Of the essential oils tested in the in vivo assay, lemongrass and lemon oils have the greatest potential. Oranges that were exposed to 0.05% lemongrass oil, 0.25% and 0.5% lemon oil were protected for 30 days when stored at 4ºC or room temperature. They provided the best antifungal activity compared to the other concentrations of all four essential oils tested as well as fungicide treatment for 30 days. Of all the treatment tested, 0.05% lemongrass oil, 0.25% and 0.5% lemon oil appeared to be the most promising treatments. However, these treatments need to be tested for antifungal effects, fruit quality, flavour and nutritional effects in large scale experiments before they can be applied as replacements to currently used fungicides. Also, essential oils are complex compounds; therefore it would be of interest to determine the active compound(s) of the lemongrass and lemon oils.