Authors are with Food, Nutrition and Health, Faculty of Land and Food Systems, the Univ. of British Columbia 2205 East Mall, Vancouver, BC V6T-1Z4, Canada.
J Food Sci. 2018 Aug;83(8):2039-2046. doi: 10.1111/1750-3841.14277. Epub 2018 Jul 25.
Essential oil constituents (EOCs) derived from antimicrobial plant extracts can be used for organic preservation of food products. However, the characteristic flavor resulting from EOCs limit the concentration that can be used in high-pH beverages. This work provides an innovative approach of organically preserving a high-pH beverage (watermelon juice) with a natural blend of low-pH fruits (apples and lemons) and EOCs simultaneously. This low-pH fruit blend not only lowers the pH of the food to below critical pH (4.6), but also reduces the potential off-flavors of EOCs, offering a good preservation approach. This was verified using a sensory trial (n = 50) coupled with storage studies and evaluation of various quality parameters using an extreme vertices mixture design with varying proportions of the fruit-base (watermelon juice), the acidulant (apple-lemon juice blend), and the antimicrobial agent (EOC blend). EOC and acidulant containing juices received better sensory scores than those without acidulant, but lower than when EOCs were absent. Microbial load of juices with EOCs after 14 days of storage did not deviate from day 0, while those without EOCs increased 3-fold on a logarithmic scale. Juices containing EOCs also had higher total phenolic content and antioxidant capacity. However, presence of EOCs did not impact pH, total soluble solids, titratable acidity or color, while acidification had significant effects on pH and titratable acidity. Optimum composition of juice formulations were prescribed according to a multi-parameter optimization algorithm. We concluded that the process of natural acidification (with apple-lemon juice blend) coupled with antimicrobial plant extracts is successful in extending the shelf-life of fruit juices with minimal effects on quality/sensory parameters.
This research proposes using a unique method for organic preservation of juices using very small amounts of essential oil constituents and acidification. Off-flavors that may arise can be mitigated without the use of chemical additives, but rather with a blend of tart fruit juices, such as apple and lemon juices. The EOCs and the acidulant act synergistically as a hurdle to inhibit microbial growth, so that thermal processing does not need to be employed.
从抗菌植物提取物中获得的精油成分（EOC）可用于食品的有机保鲜。然而，EOC 产生的特征风味限制了其在高 pH 值饮料中的使用浓度。本工作提供了一种创新的方法，即用低 pH 值的水果（苹果和柠檬）和 EOC 的天然混合物同时有机地保存高 pH 值的饮料（西瓜汁）。这种低 pH 值的水果混合物不仅将食品的 pH 值降低到临界 pH（4.6）以下，而且还降低了 EOC 的潜在异味，提供了一种良好的保鲜方法。这是通过感官试验（n = 50）与贮藏研究相结合，并使用极值顶点混合设计，用不同比例的水果基（西瓜汁）、酸化剂（苹果-柠檬果汁混合物）和抗菌剂（EOC 混合物）来评估各种质量参数来验证的。含有 EOC 和酸化剂的果汁的感官评分高于不含酸化剂的果汁，但低于不含 EOC 的果汁。贮藏 14 天后，含有 EOC 的果汁的微生物负荷与第 0 天相比没有偏差，而不含 EOC 的果汁的微生物负荷则增加了 3 倍。含有 EOC 的果汁还具有较高的总酚含量和抗氧化能力。然而，EOC 的存在并不影响 pH 值、总可溶性固形物、可滴定酸度或颜色，而酸化对 pH 值和可滴定酸度有显著影响。根据多参数优化算法规定了果汁配方的最佳组成。我们得出结论，用苹果-柠檬果汁混合物进行自然酸化（with apple-lemon juice blend），同时加入抗菌植物提取物，成功地延长了果汁的保质期，对质量/感官参数的影响最小。
本研究提出了一种使用少量精油成分和酸化的独特方法对果汁进行有机保鲜。可以通过使用混合的酸味水果汁（如苹果和柠檬汁）来减轻可能产生的异味，而无需使用化学添加剂。EOC 和酸化剂协同作用，形成障碍抑制微生物生长，因此不需要进行热加工。
