Effect of preservation methods on nutrient quality of basil (Ocimum basilicum) leaves

Abstract

Drying or “dehydrating” is a method of food preservation that removes enough moisture from the raw food materials so bacteria, yeast and molds cannot grow. This method helps spicy herbs to inhibiting the growth of microorganisms and preventing the biochemical reactions that may alter the organoleptic and nutritional characteristics of the dried leaf. However, drying must be performed carefully in order to preserve the aroma, appearance and nutritional characteristic herbs as much as possible. The main object of this research was to evaluate the best method of preservation and its influence on the quality of different varieties basil. The experiments were carried out at the laboratory of Institute of Agriculture and food sciences at Aleksandras Stulginskis University in 2016. Five varieties of basil (Ocimum basilicum) 'Lemon', 'Purple Opal', 'Cinamon', 'Toscano' and 'Verde Foglia Fine' were investigated. Basil leaves have been preserved using four different methods: drying at 25 oC and 40 oC in a thermostat, lyophilized, freezing at -25 oC. By standardized methods herbs have been analysed for ascorbic acid (mg g-1), chlorophyll a and b, and total chlorophyll (mg g-1), carotenoids (mg g-1) and color (value L*a*b* scale). The experimental data were statistically processed by the dispersion analysis method (ANOVA), software STATISTIKA 7.0 (StatSoft, USA). Arithmetical means and standard errors of the experimental data were calculated. Tukey test (p<0.05) was applied to estimate statistical significance of differences. The essential biggest amount of ascorbic acid were determined in thermostat drying at 25 °C and lyophilized 'Toscano' and 'Lemon' basil leaves. Preserving methods have been significantly influence on amount of chlorophylls and carotenoids. The lyophilized basil leaves of 'Lemon', 'Cinamon', 'Toscano' and 'Verde Foglia fine' have been accumulated the highest amount total chlorophylls and carotenoids