Document Type

Theses, Masters

Rights

This item is available under a Creative Commons License for non-commercial use only

Publication Details

Theses submitted for the award of M.Phil, School of Food Science and Environmental Health, Faculty of Tourism and Food, June, 2008.

Abstract

The average intake of vegetables in Ireland falls below the recommendations of Bord Glas and FSAI. Carrots are the third most consumed vegetable in Ireland and they are an excellent source of vitamins A and B as well as phytochemicals. Lactic acid bacteria (LAB) are well-known in food for their benefits such as improvement of the nutritional value of food and improvement of the digestion of lactose. Vegetable consumption could be enhanced by promoting a novel snack fermented carrot product that would provide the healthy benefits of vegetables coupled with the benefits of the probiotic lactic acid bacteria. Two varieties of carrots, Amsterdam (baby carrots) and Nantes half-long were chosen for this study due to their availability throughout the year. Carrot sticks (90 mm x 5 mm x 5 mm) were produced to standardize and reduce the heterogeneity of the raw material. The initial levels of total viable counts on Amsterdam carrots were established at 2.0x105 cfu/g. Blanching treatments of a minimum of 40 seconds were required to inactivate the initial microbiological load. There were no significant differences (p<0.05) in the carrot texture after 40 seconds of blanching. A carrot juice broth (CJB) was prepared in which the growth of a mixed culture of L. plantarum and L. brevis was not significantly different (p<0.05) to the MRS broth after 48 hours of fermentation. Fermentation studies of vacuum-packed carrot sticks were carried out analysing the effect of 2 factors: pH and LAB load (log cfu/g) and 4 variables: dipping time meaning the period of time that carrot sticks were immersed in the CJB inoculated with LAB at different concentrations (1/2/4 hours), initial LAB concentration of CJB (106/107/108 cfu/g), storage temperature (4/10/25ºC) and storage time (0/1/7/14 days). ANOVA and variable interactions studies concluded that conditions such as dipping time of 1 hour, storage temperature of 25ºC and storage time of 7 days were optimal for fermented carrot sticks production. A preliminary sensory analysis found no significant differences between fermented carrot sticks (1 day) and unfermented carrot sticks (raw and blanched) in terms of brightness, orange colour and the overall visual quality implying its acceptability by the panel. This study proved that carrot sticks may be fermented by lactic acid bacteria in vacuum conditions.l

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