MICROBIOLOGICAL AND CHEMICAL PROPERTIES OF TRADITIONALLY PRODUCED APPLE, BLACKTHORN, HAWTHORN AND PEAR VINEGAR

Abstract

The aim of this paper is to determine the quality of vinegars through microbiological and chemical properties using simple chemical and microbiological analysis in different types of vinegar from apple (Malus sp.), blackthorn, (Prunus spinosa L.), hawthorn (Crataegus sp.) and pear (Pyrus sp.) obtained in a traditional manner. The amount of acetic acid in vinegar in this investigation varied between 0.72% to 4.5% for the samples.

In apple vinegar, the total number of bacteria amounts to 16 cfu/mL, consists of only acetic bacteria, contains 4.0% acetic acid and has 3.25 pH value. In the samples of blackthorn and hawthorn vinegar, a very small number (6 cfu/mL and 5 cfu/mL respectively) of acetic bacteria was present. Also, a low acidity (pH about 1.0) was found and microscopy revealed Gram (+) rod-shaped asporogenous bacteria (41 cfu/mL in blackthorn and 35 cfu/mL in hawthorn vinegar) and a near absence of acetic bacteria. Hence, samples of blackthorn and hawthorn vinegar were found to undergo no acetic fermentation process at all, meaning the final product is not vinegar. In pear vinegar, the total number of bacteria is 25 cfu/mL and acetic bacteria 16 cfu/mL, it has the highest percentage of acetic acid (4.5%). Yeast cells were observed under the microscope which is characteristic of alcoholic fermentation. Due to it, the process of obtaining the final product goes in an unwanted direction.

А very high negative correlation between pH and acetic acid was determined and between the total number of bacteria and the number of acetic bacteria.