Tesis doctoral de Sheila Benítez González
Nowadays consumers demand fast foods with high nutritional and sensory quality preserved with the minimum quantity of additives. Increase in respiration rates, changes in color, softening or microbial proliferation are negatives consequences of fresh-cut processing operations. Many factors including cultivar, maturity stage, temperatures or packaging atmospheres may affect the physiological response of the fruit. Controlled/ modified atmospheres are often used to extend the shelf-life of vegetables but in most cases, this technique is not effective enough to provide high quality minimally processed fruits. based on this approach, we will identify the parameters that define the quality losses associated with minimally processed pineapple and kiwifruit. Optimal ripeness of raw material for processing and the physiological response to different temperatures measured as respiration rate and as texture loss were evaluated to improve the quality of fresh-cut pineapple. After determining the influence of these key factors, the effect of calcium salts (calcium lactate and calcium ascorbate) and edible coatings (chitosan and alginate) on the metabolic activity and physico-chemical parameters of minimally processed pineapple stored at 4 ± 1 °c were evaluated. Optimum ripening stage and packaging conditions were evaluated for minimally processed kiwifruit. Thereafter the effect of edible coatings based on aloe vera (1, 5 and 15%), chitosan formulated with citric or acetic acid and alginate in the shelf-life and sensory quality of kiwifruit slices were evaluated during 12 days under refrigerated storage at 4 ± 1 °c. The results presented in this study show that fresh-cut pineapple presents a low-moderate respiration rate that depends on the surrounding gas concentrations (according to a michaelis-menten enzymatic model with no inhibition) and exponentially with temperature changes, with texture softening that is minimized when the fresh-cut fruit is stored at low temperatures. When a break in the cold chain during storage was simulated, an increase in the respiration rate supposed a significant modification of the o2 and co2 concentrations inside the fresh-cut pineapple packages. Studies during the fresh-cut pineapple storage, state that the nutritional and physiological quality of minimally processed pineapple is optimal up to 15 days when calcium lactate was applied and the fruit was stored at 4 ± 1 °c. the greater improvements were browning inhibition, reduction of juice leakage and reduction of ascorbic acid degradation. Low o2 and high co2 concentrations inside the packages do not seem to induce an anaerobic metabolism in minimally processed pineapple whilst high co2 concentrations are associated with decreasing luminosity. Chitosan or alginate edible coatings did not significantly reduce the gas exchange in the pineapple wedges; however those formulated with aloe vera, chitosan and alginate reduced the kiwifruit slices gas exchange. However, there was an increase of o2 consumption and co2 production in kiwifruit slices coated with chitosan formulated with citric acid and alginate after 8 days of storage. This fact was consistent with an increase in the microbial populations. Aloe vera and chitosan combined with citric acid edible coatings can extend the fresh-cut kiwifruit shelf-life up to 12 days. Both aloe vera and chitosan formulated with acetic acid decreased the microbial counts but the sensory analysis reveals that the coatings based on alginate or chitosan formulated with acetic acid provides humidity, brightness and undesirable flavors to kiwifruit slices.
Datos académicos de la tesis doctoral «Estrategias de mejora de la calidad en piña (ananas comosus (l.) merr.) y kiwi (actinidia deliciosa lindl.) mínimamente procesados.«
- Título de la tesis: Estrategias de mejora de la calidad en piña (ananas comosus (l.) merr.) y kiwi (actinidia deliciosa lindl.) mínimamente procesados.
- Autor: Sheila Benítez González
- Universidad: Politécnica de catalunya
- Fecha de lectura de la tesis: 16/12/2013
Dirección y tribunal
- Director de la tesis
- Montserrat Pujola Cunill
- Tribunal
- Presidente del tribunal: m. monserrat Ferrado cogollos
- ramón Gervilla fernández (vocal)
- (vocal)
- (vocal)