Wageningen Food & Biobased Research, Wageningen University & Research. P.O. Box 17, 6700 AA Wageningen, the Netherlands.
Wageningen Food & Biobased Research, Wageningen University & Research. P.O. Box 17, 6700 AA Wageningen, the Netherlands.
Int J Food Microbiol. 2020 Jul 16;325:108629. doi: 10.1016/j.ijfoodmicro.2020.108629. Epub 2020 Apr 13.
High pressure processing is a mild preservation process that inactivates pathogenic and spoilage micro-organisms in food products, but preserves the fresh characteristics of a product. Compared to untreated product, an enhanced shelf life is obtained during refrigerated storage. Knowledge on the use of high pressure pasteurisation aimed for ambient storage is limited. The aim of this research was to investigate if a combination of high pressure and moderate heat could be used to produce a shelf-stable high-acid fruit product. Ascospores of the heat resistant fungi Talaromyces macrosporus and Aspergillus fischeri were added to fresh strawberry puree that served as a model system. The effect of the processing steps and storage at ambient temperature for 2 weeks was studied on viability of the ascospores. A preheating step at 69 °C/2 min resulted in full or partial activation of A. fischeri and T. macrosporus spores, respectively. The pressure build-up by the process without any holding time resulted in additional activation of spores. A combination of moderate heat (maximum 85-90 °C) and high pressure (500-700 MPa) for holding times up to 13 min inactivated these highly resistant spores much faster than a heat treatment alone. At T = 85 °C and 600 MPa the spores of T. macrosporus and A. fischeri were inactivated by 5.0 and 5.5 log after 13 and 7 min, respectively. At T = 85 °C the heat treatment alone did not reduce the viability of these spores up to 60 min of treatment. At T = 90 °C the holding time of the combined pressure-heat treatment could be reduced to obtain the same degree of inactivation of the heat resistant fungi. In addition, treated and untreated ascospores in strawberry puree were stored for 14 days at room temperature to evaluate delayed outgrowth of spores. Untreated ascospores of A. fischeri were activated by storage in the puree. However, at conditions combining high pressure ≥ 600 MPa with T ≥ 85 °C for 13 min, heat resistant fungi were successfully inactivated. This research showed that a combination of moderate heat and pressure can drastically improve the effectiveness to inactivate heat-resistant ascospores in a high-acid fruit product compared to a heat treatment, potentially resulting in a better product quality.
高压处理是一种温和的保鲜过程，可使食品中的致病微生物和腐败微生物失活，但保留产品的新鲜特性。与未经处理的产品相比，冷藏储存期间可获得更长的保质期。关于用于环境储存的高压巴氏杀菌的用途的知识有限。本研究的目的是研究高压和中等热量的组合是否可用于生产货架稳定的高酸性水果产品。耐热真菌长枝木霉和烟曲霉的分生孢子被添加到新鲜的草莓纯汁中，作为模型系统。研究了加工步骤以及在环境温度下储存 2 周对分生孢子活力的影响。69°C/2 分钟的预热步骤分别导致烟曲霉和长枝木霉孢子的完全或部分激活。无保压时间的加压过程导致孢子的进一步激活。在高达 85-90°C 的温和热（最高）和高压（500-700 MPa）的组合下，对于长达 13 分钟的保持时间，这些高度抗性的孢子比单独的热处理更快地失活。在 T=85°C 和 600 MPa 下，T. macrosporus 和 A. fischeri 的孢子在 13 和 7 分钟后分别通过 5.0 和 5.5 log 失活。在 T=85°C 下，单独的热处理不会降低这些孢子的活力，直到处理时间达到 60 分钟。在 T=90°C 下，可将高压-热处理的保持时间缩短至获得相同程度的耐热真菌失活。此外，将处理过和未处理过的分生孢子在草莓纯汁中于室温下储存 14 天，以评估孢子的延迟生长。未处理的烟曲霉分生孢子在纯汁中储存时被激活。然而，在组合高压≥600 MPa 与 T≥85°C 下处理 13 分钟的条件下，耐热真菌被成功失活。本研究表明，与热处理相比，温和热和压力的组合可以大大提高高酸性水果产品中耐热分生孢子的失活效果，从而可能提高产品质量。
