Preservation and evaluation of spiced chayote juice using hurdle technology

Abstract Chayote (Sechium edule) is a perennial climbing plant, belonging to the Cucurbitaceae family and is neglected or underutilized as a food or as a raw material in the food industry because of its bland taste. This bland taste can be overcome by blending with a suitable substrate such as sugarcane juice along with natural flavouring. However, this blending represents a preservation problem for the spiced juice, since both chayote juice and sugarcane juice are prone to microbial attack. Therefore, an attempt was made in the present study to preserve the spiced chayote juice by employing different hurdles i.e. pasteurization temperature (70 °C and 80 °C) and pasteurization time (10 and 20 min) followed by the addition of different concentrations of potassium metabisulphite (KMS) (200, 300 and 400 ppm). The samples so prepared were filled into glass bottles and stored under refrigeration for forty-five days. As the storage period proceeded there were significant decreases in pH, total protein content, total phenolic compounds, antioxidant activity, reducing power, metal chelation, tannin content, ascorbic acid content and overall acceptability, whereas there were significant increases in TSS (total soluble solids), titratable acidity, reducing sugars, total sugar, TPC (total plate count) and MIC (minimum inhibitory concentration). A cluster analysis of the data revealed that the pasteurization temperature exerted the most significant effect on the physicochemical and sensory characteristics of the spiced chayote juice as compared to the pasteurization time and KMS concentration, which failed to fall into the separate and respective clusters. In a nutshell, it was concluded that spiced chayote juice can be successfully preserved using hurdle technology (pasteurizing at 70 °C for 10 min followed by the addition of 400ppm KMS).摘要：佛手瓜（Sechium edule）为葫芦科（Cucurbitaceae）多年生攀援植物，因其风味平淡，作为食品或食品工业原料常被忽视且未得到充分利用。可通过将其与合适的基质（如甘蔗汁）复配并添加天然调味剂改善其平淡风味。但该复配调味汁存在保鲜难题：佛手瓜汁与甘蔗汁均易受微生物侵染。因此本研究尝试采用栅栏技术（hurdle technology）对调味佛手瓜汁进行保鲜，具体设置不同巴氏杀菌温度（70℃与80℃）、杀菌时间（10 min与20 min），并添加不同浓度的焦亚硫酸钾（KMS，potassium metabisulphite，200、300与400 ppm）。将制备得到的样品灌装至玻璃瓶中，于冷藏条件下保存45天。随着贮藏期推进，样品的pH值、总蛋白含量、总酚类化合物含量、抗氧化活性、还原力、金属螯合能力、单宁含量、抗坏血酸含量及总体接受度均显著下降；而总可溶性固形物（TSS）、可滴定酸度、还原糖、总糖、菌落总数（TPC，total plate count）与最低抑菌浓度（MIC，minimum inhibitory concentration）则显著上升。对数据的聚类分析结果显示，相较于杀菌时间与KMS浓度（二者未能各自形成独立聚类簇），巴氏杀菌温度对调味佛手瓜汁的理化与感官特性影响最为显著。综上，本研究得出结论：采用栅栏技术（70℃巴氏杀菌10 min，添加400 ppm KMS）可成功实现调味佛手瓜汁的保鲜。