Effects of Different Controlled Temperatures on Spanish-Style Fermentation Processes of Olives

This work aimed to determine the effect of applying different temperatures during the fermentation process of Spanish-style table olives. 'Manzanilla de Sevilla' (southwest of Spain, Badajoz) and 'Manzanilla Cacereña' (northwest of Spain, Caceres) olives were processed at an industrial scale in table olive fermenters whose brine was subjected to different thermal treatments. One of the three conducted experiments found that maintaining brine at 20-24 °C over a 3-month period led to optimum firmness, better color indices, and greater free acidity and lactic acid bacteria populations in comparison to an unheated control. Furthermore, raising the temperature of the fermenter to 20-24 °C accelerated the fermentation process, provoking better lactic bacteria and yeast growth without affecting olive firmness. The higher fermentation rate (shorter time to completion) associated with temperature-controlled olives also reduced the marketing time of the final product. Controlling brine temperature led to a better aspect and color, higher acidity, lower bitterness, and better overall assessment of processed olives. In addition, 'Manzanilla de Sevilla' olives presented a higher phenolic content than 'Manzanilla Cacereña' olives. Preliminary evidence is presented suggesting that 'Manzanilla Cacereña' olives appear highly amenable to Sevillian-style processing. The present innovative work demonstrates the importance of applying different thermal treatments to brine to control the temperature during the industrial fermentation of table olives during the cold season.