不久前，科学家利用VideometerLite便携式多光谱成像系统发表了题“Monitoring the Bioprotective Potential of Lactiplantibacillus pentosus Culture on Pathogen Survival and the Shelf-Life of Fresh Ready-to-Eat Salads Stored under Modified Atmosphere Packaging”的文章，文章发表于Pathogens。

监测戊糖乳杆菌培养物对病原体存活和在改良气氛下储存的新鲜即食沙拉的保质期的生物保护潜力包装

摘要：

在全球范围内，新鲜蔬菜或最低限度加工的沙拉与几个食源性疾病暴发有关。本文研究了戊糖乳杆菌FMCC-B281细胞（F）及其上清液（S）对鲜切即食沙拉腐败变质的影响以及单核细胞增生李斯特菌和大肠杆菌O157：H7在贮藏过程中对鲜切即食（RTE）沙拉的保质期影响。此外，傅里叶变换红外 （FTIR） 和多光谱成像 （MSI） 分析被用作快速和非破坏性技术来估计样品的微生物状况。本研究采用新鲜长叶莴苣、火箭卷心菜和白菜，接种戊糖乳杆菌和两种病原菌。将菌株分别在 37 ◦C 下在 MRS 和 BHI 肉汤中生长 24 小时，然后离心以收集上清液和沉淀物（细胞）。使用细胞 （F， ~5 log CFU/g）、上清液 （S） 和对照 （C， 肉汤） 喷洒先前被病原体污染（喷洒）的每种新鲜蔬菜的叶子 （3 log CFU/g）。随后，将沙拉包装在气调包装（10%CO2/10%O2/80%N2）下，并在4°C和10°C下储存直至变质。在储存期间，微生物计数和pH值与FTIR和MSI分析同时进行监测。结果表明，在贮藏过程中，莴苣和火箭的病原菌数量增加，与处理无关。对于卷心菜，病原体种群在整个储存过程中保持稳定。在腐败微生物群方面，F样品中的假单胞菌数量较低，而储存在4°C的C、F和S样品中的肠杆菌科和酵母菌/霉菌数量没有差异。根据感官评价，与S和F样品相比，对照样品的保质期较短，而S和F样品的保质期延长了1-2天。三种叶菜的初始pH值约为6.0。在所有叶菜的情况下，在两种温度下，pH值都增加了约0.5值，直到储存结束。FTIR和MSI分析尚不能令人满意地估计沙拉的微生物质量。总之，应用的生物保护菌株（L. pentosus）可以延长即食沙拉的保质期，而不会影响病原体的生长。

关键词：预切沙拉;生物保存;单核细胞增生李斯特菌;大肠杆菌;傅里叶变换红外（FTIR）光谱;多光谱成像 （MSI） 分析

Monitoring the Bioprotective Potential of Lactiplantibacillus pentosus Culture on Pathogen Survival and the Shelf-Life of Fresh Ready-to-Eat Salads Stored under Modifed AtmospherePackaging

Abstract:

Globally, fresh vegetables or minimally processed salads have been implicated in several

foodborne disease outbreaks. This work studied the effect of Lactiplantibacillus pentosus FMCC-B281 cells (F) and its supernatant (S) on spoilage and on the fate of Listeria monocytogenes and Escherichia coli O157:H7 on fresh-cut ready-to-eat (RTE) salads during storage. Also, Fourier transform infrared (FTIR) and multispectral imaging (MSI) analysis were used as rapid and non-destructive techniques to estimate the microbiological status of the samples. Fresh romaine lettuce, rocket cabbage, and white cabbage were used in the present study and were inoculated with L. pentosus and the two pathogens. The strains were grown at 37 ◦C for 24 h in MRS and BHI broths, respectively, and then were centrifuged to collect the supernatant and the pellet (cells). Cells (F, ~5 log CFU/g), the supernatant (S), and a control (C, broth) were used to spray the leaves of each fresh vegetable that had been previously contaminated (sprayed) with the pathogen (3 log CFU/g). Subsequently, the salads were packed under modified atmosphere packaging (10%CO2/10%O2/80%N2 ) and stored at 4 and 10 ◦C until spoilage. During storage, microbiological counts and pH were monitored in parallel with FTIR and MSI analyses. The results showed that during storage, the population of the pathogens increased for lettuce and rocket independent of the treatment. For cabbage, pathogen populations remained stable throughout storage. Regarding the spoilage microbiota, the Pseudomonas population was lower in the F samples, while no differences in the populations of Enterobacteriaceae and yeasts/molds were observed for the C, F, and S samples stored at 4 ◦C. According to sensory evaluation, the shelf-life was shorter for the control samples in contrast to the S and F samples, where their shelf-life was elongated by 1–2 days. Initial pH values were ca. 6.0 for the three leafy vegetables. An increase in the pH of ca. 0.5 values was recorded until the end of storage at both temperatures for all cases of leafy vegetables. FTIR and MSI analyses did not satisfactorily lead to the estimation of the microbiological quality of salads. In conclusion, the applied bioprotective strain (L. pentosus) can elongate the shelf-life of the RTE salads without an effect on pathogen growth.

Keywords: pre-cut salads; biopreservation; Listeria monocytogenes; Escherichia coli; Fourier transform infrared (FTIR) spectroscopy; multispectral imaging (MSI) analysis