Bonatsou Stamatoula, Iliopoulos Vasilis, Mallouchos Athanasios, Gogou Eleni, Oikonomopoulou Vasiliki, Krokida Magdalini, Taoukis Petros, Panagou Efstathios Z
Laboratory of Microbiology and Biotechnology of Foods, Department of Food Science and Human Nutrition, Agricultural University of Athens, Iera Odos 75, 11855 Athens, Greece.
Laboratory of Food Chemistry and Analysis, Department of Food Science and Human Nutrition, Agricultural University of Athens, Iera Odos 75, 11855 Athens, Greece.
Food Microbiol. 2017 May;63:72-83. doi: 10.1016/j.fm.2016.11.001. Epub 2016 Nov 3.
This study examined the effect of osmotic dehydration of Kalamata natural black olives as pre-fermentation treatment in combination with partial substitution of NaCl by monosodium glutamate (MSG) on the fermentation profile of olives. Osmotic dehydration was undertaken by immersing the olives in 70% (w/w) glucose syrup overnight at room temperature. Further on, three different mixtures of NaCl and MSG with/without prior osmotic dehydration of olives were investigated, namely (i) 6.65% NaCl - 0.35% MSG (5% substitution), (ii) 6.30% NaCl - 0.70% MSG (10% substitution), (iii) 5.95% NaCl - 1.05% MSG (15% substitution), and (iv) 7% NaCl without osmotic dehydration (control treatment). Changes in the microbial association (lactic acid bacteria [LAB], yeasts, Enterobacteriaceae), pH, titratable acidity, organic acids, sugars, and volatile compounds in the brine were analyzed for a period of 4 months. The final product was subjected to sensory analysis and the content of MSG in olives was determined. Results demonstrated that osmotic dehydration of olives prior to brining led to vigorous lactic acid processes as indicated by the obtained values of pH (3.7-4.1) and acidity (0.7-0.8%) regardless of the amount of MSG used. However, in non-osmotically dehydrated olives, the highest substitution level of MSG resulted in a final pH (4.5) that was beyond specification for this type of olives. MSG was degraded in the brines being almost completely converted to γ-aminobutyric acid (GABA) at the end of fermentation. Finally, the sensory assessment of fermented olives with/without osmotic dehydration and at all levels of MSG did not show any deviation compared to the control treatment.
本研究考察了卡拉马塔天然黑橄榄的渗透脱水作为预发酵处理，并结合用谷氨酸钠（MSG）部分替代氯化钠（NaCl）对橄榄发酵过程的影响。通过将橄榄在室温下于70%（w/w）的葡萄糖糖浆中浸泡过夜进行渗透脱水。此外，研究了三种不同的NaCl和MSG混合物，橄榄有无预先进行渗透脱水，即（i）6.65% NaCl - 0.35% MSG（5%替代），（ii）6.30% NaCl - 0.70% MSG（10%替代），（iii）5.95% NaCl - 1.05% MSG（15%替代），以及（iv）7% NaCl且无渗透脱水（对照处理）。对盐水在4个月内微生物群落（乳酸菌[LAB]、酵母、肠杆菌科）、pH值、可滴定酸度、有机酸、糖和挥发性化合物的变化进行了分析。对最终产品进行感官分析，并测定橄榄中MSG的含量。结果表明，盐水腌制前橄榄的渗透脱水导致了活跃的乳酸发酵过程，这由所获得的pH值（3.7 - 4.1）和酸度（0.7 - 0.8%）表明，与所用MSG的量无关。然而，在未进行渗透脱水的橄榄中，最高的MSG替代水平导致最终pH值（4.5）超出了此类橄榄的规格要求。MSG在盐水中被降解，在发酵结束时几乎完全转化为γ-氨基丁酸（GABA）。最后，对经过/未经过渗透脱水以及所有MSG水平的发酵橄榄进行感官评估，与对照处理相比未显示出任何差异。
