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Different microbial groups of the microbiome of fresh produce can have diverse effects on human health. This study was aimed at identifying some microbial communities of fresh produce by analyzing 105 samples of imported fresh fruits and vegetables originated from different countries in the world including local samples (Oman) for aerobic plate count and the counts of Enterobacteriaceae, Enterococcus, and Staphylococcus aureus. The isolated bacteria were identified by molecular (PCR) and biochemical methods (VITEK 2). Enterobacteriaceae occurred in 60% of fruits and 91% of vegetables. Enterococcus was isolated from 20% of fruits and 42% of vegetables. E. coli and S. aureus were isolated from 22% and 7% of vegetables, respectively. Ninety-seven bacteria comprising 21 species were similarly identified by VITEK 2 and PCR to species level. E. coli, Klebsiella pneumoniae, Enterococcus casseliflavus, and Enterobacter cloacae were the most abundant species; many are known as opportunistic pathogens which may raise concern to improve the microbial quality of fresh produce. Phylogenetic trees showed no relationship between clustering of the isolates based on the 16S rRNA gene and the original countries of fresh produce. Intercountry passage of opportunistic pathogens in fresh produce cannot be ruled out, which requires better management.

In an attempt to initiate seafood biotechnology in the Sultanate of Oman, Middle East, using underutilized fish, fish burgers from two different formulas were developed and the quality and storage stability were evaluated during storage at -20∞C for 3 months. Quality and storage stability were evaluated through total aerobic and coliform bacterial count, peroxide value, protein solubility, and color. Total aerobic bacteria were reduced significantly (P < 0.05) by 84% and 97% of the initial load in formulas 1 and 2, respectively, whereas coliforms were completely destroyed in both formulas at the end of storage. Peroxide value increased (P < 0.05) but did not reach detectable levels of rancidity. Salt-soluble protein content decreased remarkably during the storage period. The L value showed good stability during storage, keeping products bright for 3 months. Fish burgers from both formulas were acceptable for 3 months at -20∞C. Storage stability was rationalized by the effectiveness of freezing, and antimicrobial and antioxidant properties of food additives.KEY WORDS: aerobic bacteria, coliforms, fish burger, peroxide value, quality, storage stability.

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BackgroundDate palm has been a major fruit tree in the Middle East over thousands of years, especially in the Arabian Peninsula. Dates are consumed fresh (Rutab) or after partial drying and storage (Tamar) during off-season. The aim of the study was to provide in-depth analysis of fungal communities associated with the skin (outer part) and mesocarp (inner fleshy part) of stored dates (Tamar) of two cultivars (Khenizi and Burny) through the use of Illumina MiSeq sequencing.ResultsThe study revealed the dominance of Ascomycota (94%) in both cultivars, followed by Chytridiomycota (4%) and Zygomycota (2%). Among the classes recovered, Eurotiomycetes, Dothideomycetes, Saccharomycetes and Sordariomycetes were the most dominant. A total of 54 fungal species were detected, with species belonging to Penicillium, Alternaria, Cladosporium and Aspergillus comprising more than 60% of the fungal reads. Some potentially mycotoxin-producing fungi were detected in stored dates, including Aspergillus flavus, A. versicolor and Penicillium citrinum, but their relative abundance was very limited (<0.5%). PerMANOVA analysis revealed the presence of insignificant differences in fungal communities between date parts or date cultivars, indicating that fungal species associated with the skin may also be detected in the mesocarp. It also indicates the possible contamination of dates from different cultivars with similar fungal species, even though if they are obtained from different areas.ConclusionThe analysis shows the presence of different fungal species in dates. This appears to be the first study to report 25 new fungal species in Oman and 28 new fungal species from date fruits. The study discusses the sources of fungi on dates and the presence of potentially mycotoxin producing fungi on date skin and mesocarp.

Enterobacteria may gain antibiotic resistance and be potent pathogens wherever they are present, including in fresh fruits and vegetables. This study tested the antibiotic resistance of enterobacteria isolated from 13 types of local and imported fresh fruits and vegetables (n = 105), using the standard Kirby-Bauer disk diffusion method. Phenotypic and genotypic characterizations of AmpC β-lactamases were determined in cefoxitin-resistant isolates. Ten percent of the enterobacteria tested (n = 88) were pansusceptible, 74% were resistant to at least one antibiotic, and 16% were multidrug resistant. Enterobacteria isolates showed the highest antibiotic resistance against ampicillin (66%), cephalothin (57%), amoxicillin–clavulanic acid (33%), cefoxitin (31%), tetracycline (9%), nalidixic acid (7%), trimethoprim (6%), and kanamycin (5%). Three isolates showed intermediate resistance to the clinically important antibiotic imipenem. Escherichia coli isolated from lettuce exhibited multidrug resistance against five antibiotics. Fifteen isolates were confirmed to have AmpC β-lactamase, using the inhibitor-based test and the antagonism test; the latter test confirmed that the enzyme was an inducible type. Four types of ampC β-lactamase genes (CIT, EBC, FOX, and MOX) were detected in eight isolates: four Enterobacter cloacae isolates and one isolate each of Citrobacter freundii, Enterobacter asburiae, Enterobacter hormaechei, and Enterobacter ludwigii. It was concluded that fresh fruits and vegetables might play a role as a source or vehicle for transferring antibiotic-resistant bacteria that might spread to other countries through exportation. The clinically significant AmpC β-lactamase was rarely documented in the literature on bacteria isolated from fruits and vegetables, and to our knowledge, this is the first report on the detection of an inducible type in such commodities.

The effect of frozen storage on the physiochemical, chemical and microbial characteristics of two types of fish sausages was studied. Fish sausages developed (DFS) with a spice-sugar formulation and commercial fish sausages (CFS) were stored at -20 °C for 3 months. Fresh DFS contained 12.22% lipids and had a 3.53 cfu/g total bacteria count (TBC) whereas, CFS contained 5.5% lipids and had a 4.81 cfu/g TBC. During storage, TBC decreased significantly (p < 0.05) in DFS whereas it did not change (p > 0.05) in CFS. A peroxide value (PV) was not detectable until week four and eight of storage in CFS and DFS, respectively. The salt-soluble proteins (SSP) level was stable in DFS but in CFS it declined significantly (p < 0.05). Colour values did not change significantly (p > 0.05) in both sausage types. This study showed that the effect of storage at -20 °C on fish sausages characteristics varied between formulations and depended on the ingredients of fish sausages.

Traditional fish burgers are made mostly with added starch but fail to meet consumer expectations of eating quality characteristics. Improved formulations, however, can offer a new marketing position in the area of processed fish products. Promising functional ingredients that can improve organoleptic properties include milk protein, citrus pectin, and bovine gelatin. The large deformation properties of these burgers were identified using compression testing and specific attributes were related to the overall acceptability of the product on the basis of a hedonic scaling method. The quality of the burgers was further manipulated by introducing additional ingredients to the formulation, e.g., soya protein, k-carrageenan, frozen vegetables, and dried fruits. Distinctive upper and lower bounds of the values of hardness, firmness, adhesiveness, and the ratio of inflectional to maximum stress were defined in relation to optimum sensory acceptability of the product.