Ruiz-Barba José Luis, Sánchez Antonio Higinio, López-López Antonio, Cortés-Delgado Amparo, Montaño Alfredo
Food Biotechnology Department, Instituto de la Grasa (CSIC), Carretera de Utrera, Km. 1, 41013 Seville, Spain.
Foods. 2023 Jun 15;12(12):2386. doi: 10.3390/foods12122386.
Microbial and biochemical changes in the brine during the spontaneous fermentation of Gordal, Hojiblanca and Manzanilla olive cultivars processed according to the natural style were monitored. The microbial composition was assessed through a metagenomic study. Sugars, ethanol, glycerol, organic acids and phenolic compounds were quantified by standard methods. In addition, the volatile profiles, contents of phenolic compounds in the olives and quality parameters of the final products were compared. Fermentation in Gordal brines was conducted by lactic acid bacteria (mainly and ) and yeasts (mainly , and ). In Hojiblanca and Manzanilla brines, halophilic Gram-negative bacteria (e.g., , and ) along with yeasts (mainly, ) were responsible for the fermentation. Higher acidity and lower pH values were reached in Gordal brines compared to Hojiblanca and Manzanilla. After 30 days of fermentation, no sugars were detected in Gordal brine, but residual amounts were found in the brines from Hojiblanca (<0.2 g/L glucose) and Manzanilla (2.9 g/L glucose and 0.2 g/L fructose). Lactic acid was the main acid product in Gordal fermentation, whereas citric acid was the predominant organic acid in the Hojiblanca and Manzanilla brines. Manzanilla brine samples showed a greater concentration of phenolic compounds than Hojiblanca and Gordal brines. After a 6-month fermentation, Gordal olives were superior compared to the Hojiblanca and Manzanilla varieties regarding product safety (lower final pH and absence of ), content of volatile compounds (richer aroma), content of bitter phenolics (lower content of oleuropein, which resulted in less perceived bitterness) and color parameters (more yellow and lighter color, indicating a higher visual appraisal). The results of the present study will contribute to a better understanding of each fermentation process and could help to promote natural-style elaborations using the above-mentioned olive cultivars.
对按照自然方式加工的戈尔达尔、霍吉布兰卡和曼萨尼拉橄榄品种在自发发酵过程中卤水中的微生物和生化变化进行了监测。通过宏基因组学研究评估微生物组成。采用标准方法对糖、乙醇、甘油、有机酸和酚类化合物进行定量。此外，还比较了挥发性成分、橄榄中酚类化合物的含量以及最终产品的质量参数。戈尔达尔卤水的发酵由乳酸菌（主要是和）和酵母（主要是、和）进行。在霍吉布兰卡和曼萨尼拉卤水中，嗜盐革兰氏阴性菌（如、和）以及酵母（主要是）负责发酵。与霍吉布兰卡和曼萨尼拉相比，戈尔达尔卤水的酸度更高，pH值更低。发酵30天后，在戈尔达尔卤水中未检测到糖，但在霍吉布兰卡（<0.2 g/L葡萄糖）和曼萨尼拉（2.9 g/L葡萄糖和0.2 g/L果糖）的卤水中发现了残留量。乳酸是戈尔达尔发酵中的主要酸产物，而柠檬酸是霍吉布兰卡和曼萨尼拉卤水中的主要有机酸。曼萨尼拉卤水样品中的酚类化合物浓度高于霍吉布兰卡和戈尔达尔卤水。经过6个月的发酵，在产品安全性（最终pH值较低且无）、挥发性化合物含量（香气更浓郁）、苦味酚类含量（橄榄苦苷含量较低，导致苦味较轻）和颜色参数（更黄且颜色更浅，表明视觉评价更高）方面，戈尔达尔橄榄优于霍吉布兰卡和曼萨尼拉品种。本研究结果将有助于更好地理解每个发酵过程，并有助于推广使用上述橄榄品种的自然方式加工。
