Malolactic fermentation is a key part in the process of cider making, as it reduces acidity. Malic acid, a common component in fruit, undergoes a chemical transformation, turning into lactic acid. In the case of Basque natural cider (unlike with wine), after this process there is not normally any microbiological stabilisation treatment. This means that the lactic bacteria become the dominant microbiota. Some of these bacteria cause alterations that can affect the properties of the cider.
Biochemist, Mr Gaizka Garai investigated these bacteria, especially those that might make the cider bitter; this problem could affect the consumption of the drink. His PhD thesis is entitled Lactic bacteria of natural cider: involvement in alterations and probiotic potential of producer strains of (1,3)(1,2)--D-glucans.
Fructose, acidity and cold as factors
Some of the lactic bacteria that arise from fermentation metabolises glycerol and, as a consequence, produces the 3-HPA compound, which has a direct relation with an increase in bitterness. With this phenomenon in mind for his thesis, Mr Garai investigated what induced the presence of 3-HPA in Basque natural cider. As the researcher was able to clarify, the microbiota involved in the alteration of bitterness in natural cider is Lactobacillus collinoides. As regards other factors, the composition of the cider itself can cause this alteration. In fact, fructose (with a high concentration of sugar) facilitates the degradation of glycerol in the process of metabolism, in turn producing the accumulation of 3-HPA. Finally, the degree of acidity of the cider and the cold temperatures undergone in periods of maturing and storage can help the maintenance of 3-HPA.
Contains biogenic amines, but in small quantities
Lactic bacteria are not only a source of change in the bitterness; some of these are also producers of biogenic amines, which can produce toxic effe
|Contact: Amaia Portugal|