W. Tesfaye

Wine vinegar: technology, authenticity and quality evaluation

Abstract Wine vinegar is produced in most Mediterranean countries and extensively used as a condiment, acidifying and food preserving agent. Traditional production requires maturation in wood for many years to obtain a high acetic degree and the resulting product is relatively expensive. New technologies are being designed to overcome this difficulty with the objective of producing vinegars with a similar quality and at the same time less expensive. These methods of production involve the use of submerged bacterial culture and a continuous aeration system. Recent research is focussed in improving yield and quality of the final product.

Effect of barrel design and the inoculation of Acetobacter pasteurianus in wine vinegar production

The traditional production of wine vinegar is a lengthy process with little or no microbiological control. The aim of this study was to shorten the acetification process via three different strategies: changes in wood type; barrel shape; and the inoculation of an Acetobacter pasteurianus pure culture. The barrel shape was modified by constructing two prototypes with higher liquid-air interface. We compared the changes in acetic acid bacteria (AAB) population dynamics in these barrels with those of a submerged method. The wood type had no effect on the acetification length, whereas the shape of the barrel resulted in a significant shortening of the acetification length. Although the selected AAB strain did not always take over, it reduced the biodiversity of the AAB. The inoculated strain was predominant in oak barrels, whereas in the highly aerated prototypes Gluconacetobacter species (Ga. intermedius and/or Ga. europaeus) displaced A. pasteurianus, as what occurs in the submerged method.

Improvement of Wine Vinegar Elaboration and Quality Analysis: Instrumental and Human Sensory Evaluation

Technical improvement of vinegar production encompasses essential modifications to obtain quality products in a relatively short period of time. There are mainly two types of acetic fermentation processes to elaborate vinegar: surface and submerged culture system. High quality products are elaborated by the surface culture system. Quality, as a degree of excellence, is a subjective concept where human sensory organs play an important role to determine the acceptability of a product by the consumer. The quality of vinegars can be evaluated by using a trained sensory panel, but more rapid and objective characterization is achieved by instrumental measurements. Physicochemical analyses are generally aimed at meeting of legislative requirements for the quality, safety and characterization of foods or condiments like vinegar. Sensory analysis is a good tool to determine the category and degree of acceptance of given vinegars. Unfortunately, sensory analysis of vinegar is very difficult to perform since the pungent sensation restricts the number of samples that can be analysed at a time. Therefore, the appropriate sensory analysis method must be clearly defined and the attributes used in discriminant analysis or descriptive tests should be precise and well recognized by the panel.