Osmotic dehydration, blanching and gamma irraditation treatments for the preservation of strawberries as a semi-processed product /
Arturo Hernández Montes
- xiv, 167 hojas : gráficas, tablas
Tesis
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Osmotically dehydrated berries with water activities 0.99, 0.98 and 0.95 were blanched, gamma irradiated with 0.3, 0.6 and 0.9 kGy and analyzed for chemical and physical within 72 hr. Modified quantitative descriptive analysis or selected sensory attributes was done after 30 days of frozen storage. Vitamin C, anthocyanins, polymeric color, color density, firmness and both strawberry aromatics and flavor were lower the lower the Aw. Strawberry aroma and flavor of berries irradiated at 0.6 and 0.9 kGy were less intense than those at 0.3 kGy. Chemical aroma and flavor of strawberries were greater at A of 0.95 when irradiated with 0.6 kGy than with 0.3 or 0.9 kGy. The cooked aroma and flavor were greater at 0.6 kGy than at either 0.3 or 0.9 kGy. Irradiation was not detrimental to the chemical and physical characteristics of strawberries; however sensorially, differences were found among strawberries irradiated with different doses. Fungal growth in untreated fresh strawberries was higher than in the treated berries. The difference in fungal growth in strawberries that were blanched and those that were blanched- irradiated was not statistically significant. The mild irradiation treatment had no further effect on fungal growth of blanched berries. An irradiation dose of 0.9 kGy delayed growth of Mucor sp. on agar at 23°C for 5 days. Color brightness or non-treated strawberries decreased with storage. Blanched strawberries retained their brightness during storage; but the the color of blanched-irradiated samples was duller than the blanched berries after the fourth week of storage. Sensory attributes of jams prepared from some selected treatments (Osmotic dehydration, blanching and irradiation) were evaluated using modified quantitative descriptive analysis. NO difference was perceived between jams prepared rom the blanched strawberries and the blanched-irradiiated strawberries, Osmot ically dehydrated berries produced jams with a greater coOked flavor than other treatments. Control frozen strawberry jams were the least sour of all jams. No differences among treatments were found for strawberry aroma, fermented aroma and sweetness. Selva strawberries Were irradiated with 0.9 kGy and analyzed for furaneol and mesifurane content. No statistical difference in mesifurane and furaneol content of fresh and irradiated strawberries was found. Variation among replicates and a poor recovery of the internal standard were obtained.