Department of Animal and Food Sciences, University of Delaware, Newark, Delaware 19716, USA.
J Food Prot. 2021 Mar 1;84(3):418-423. doi: 10.4315/JFP-20-296.
Plant-derived proteases, bromelain, papain, and ficin, are broad-acting enzymes with generally recognized as safe status for foods and have current application in several food industries. These proteases have also been reported to have antimicrobial properties. This study investigated the efficacy of commercially prepared bromelain, papain, and ficin, individually and combined (2,500 ppm of crude extract), for inactivation of hepatitis A virus (HAV) and human norovirus surrogates, Tulane virus (TV), and murine norovirus (MNV). Various treatment temperatures (45, 50, or 55°C), times (10 or 60 min), and pH values (5.5 or 7.0) in the presence of cysteine (2 mM) were evaluated. Inactivation was assessed by infectivity in plaque assay for TV and MNV and by median tissue culture infective dose for HAV. No reduction in infectious TV or HAV was attributed to the plant-derived proteases at any of the conditions tested. Infectious MNV was reduced by 1 to 3 log PFU/mL; the most effective treatment was bromelain at pH 7 and 50°C for 10 min. A time course study with MNV in bromelain at 50°C indicated that a 2-log PFU/mL reduction could be achieved within 6 min, but extended treatment of 15 min was still insufficient to eliminate infectious MNV. The lack of or limited efficacy of bromelain, papain, and ficin on HAV, TV, and MNV, even at elevated temperatures and exposure times, suggests the plant-derived proteases are not commercially applicable for inactivation of virus on commodities or materials that could not also withstand mild heat treatment. The variable susceptibilities observed between TV and MNV illustrate limitations in utilization of surrogates for predicting pathogen behavior for a structure-specific treatment.
植物来源的蛋白酶，如菠萝蛋白酶、木瓜蛋白酶和无花果蛋白酶，是具有广泛作用的酶，其在食品中通常被认为是安全的，并且目前在多个食品工业中有应用。这些蛋白酶也被报道具有抗菌特性。本研究分别研究了市售菠萝蛋白酶、木瓜蛋白酶和无花果蛋白酶单独使用和联合使用（粗提物 2500ppm）对甲型肝炎病毒（HAV）和人诺如病毒替代物、图兰病毒（TV）和鼠诺如病毒（MNV）的灭活效果。在存在半胱氨酸（2mM）的情况下，评估了不同的处理温度（45、50 或 55°C）、时间（10 或 60min）和 pH 值（5.5 或 7.0）。通过 TV 和 MNV 的噬菌斑试验和 HAV 的半数组织培养感染剂量（TCID50）评估病毒的失活情况。在测试的任何条件下，植物来源的蛋白酶都没有降低传染性 TV 或 HAV。传染性 MNV 减少了 1 至 3 个对数 PFU/mL；最有效的处理方法是在 pH 值为 7 和 50°C 下处理 10 分钟的菠萝蛋白酶。在 50°C 下用 MNV 进行的时间过程研究表明，6 分钟内可实现 2 个对数 PFU/mL 的减少，但延长 15 分钟的处理仍不足以消除传染性 MNV。即使在高温和暴露时间下，菠萝蛋白酶、木瓜蛋白酶和无花果蛋白酶对 HAV、TV 和 MNV 的效果有限或无效，这表明植物来源的蛋白酶不适用于不能承受温和热处理的商品或材料上的病毒灭活。TV 和 MNV 之间观察到的差异敏感性说明了在针对特定结构的治疗中，利用替代物预测病原体行为的局限性。
