Food Handling Practices for Apple Drying in Home Kitchens in the United States: A Survey

ABSTRACT

Fruit drying has traditionally received little food safety attention in spite of Salmonella outbreaks and recalls involving low-moisture foods. This study was conducted to assess the food safety implications during the home drying process, with dried apples as an example. A cohort of home apple dryers (n = 979) participated in an online survey through Qualtrics XM in May 2021. The results showed that participants' knowledge of safe food handling practices regarding dried fruit was low. On average, participants used only 8 of 18 identified food safety practices during apple drying. The survey revealed inadequate frequency of hand washing during apple preparation, potential points of cross-contamination from kitchen tools, lack of hurdle technology without a pretreatment step, failure to incorporate a thermal kill step during drying, and a lack of objective measurements to ensure that target parameters are attained. Participants mainly pretreated apples for sensory improvement instead of microbial reduction. When presented with some benefits of pretreatment, participants who did not pretreat their apples considered doing so to kill bacteria. The use of safe food handling practices differed within demographic groups. Participants 18 to 39 years old (mean = 7.47; 95% confidence interval [CI] = 7.26, 7.67) and 40 to 59 years old (mean = 7.43; 95% CI = 7.16, 7.70) reported using fewer safe practices than did those >60 years old (mean = 8.49; 95% CI = 8.22, 8.75), and participants who identified as male (mean = 7.38; 95% CI = 7.16, 7.60) reported using fewer safe practices than did those identifying as female (mean = 7.92; 95% CI = 7.74, 8.11). The findings of this study provide food handling data to support the development of more accurate food safety risk assessment models and to guide the development of food safety education for consumers who dehydrate produce in the home.

HIGHLIGHTS

Changes in the genomes and methylomes of three Salmonella enterica serovars after long-term storage in ground black pepper

Low moisture foods (LMFs) have traditionally been recognized as safe for consumption, as most bacteria require higher water content to grow. However, outbreaks due to LMF foods are increasing, and the microbial pathogen Salmonella enterica is frequently implicated. S. enterica can survive in LMFs for years, but few serovars have been studied, and the mechanisms which underlie this longevity are not well understood. Here, we determine that S. enterica serovars S. Tennessee, S. Anatum, and S. Reading but not S. Oranienburg can survive in the ground black pepper for 6 years. S. Reading was not previously associated with any LMF. Using both Illumina and Pacific Biosciences sequencing technologies, we also document changes in the genomes and methylomes of the surviving serovars over this 6-year period. The three serovars acquired a small number of single nucleotide polymorphisms (SNPs) including seven substitutions (four synonymous, two non-synonymous, and one substitution in a non-coding region), and two insertion-deletions. Nine distinct N6-methyladenine (m6A) methylated motifs across the three serovars were identified including five which were previously known, G^m6ATC, CAG^m6AG, BATGC^m6AT, CRT^m6AYN⁶CTC, and CC^m6AN⁷TGAG, and four novel serovar-specific motifs, GRT^m6AN⁸TTYG, GA^m6ACN⁷GTA, GAA m^6ACY, and CAA^m6ANCC. Interestingly, the BATGCAT motif was incompletely methylated (35–64% sites across the genome methylated), suggesting a possible role in gene regulation. Furthermore, the number of methylated BATGC^m6AT motifs increased after storage in ground black pepper for 6 years from 475 to 657 (S. Tennessee), 366 to 608 (S. Anatum), and 525 to 570 (S. Reading), thus warranting further study as an adaptive mechanism. This is the first long-term assessment of genomic changes in S. enterica in a low moisture environment, and the first study to examine the methylome of any bacteria over a period of years, to our knowledge. These data contribute to our understanding of S. enterica survival in LMFs, and coupled with further studies, will provide the information necessary to design effective interventions which reduce S. enterica in LMFs and maintain a healthy, safe food supply.