Fungal Presence in Selected Tree Nuts and Dried Fruits

Abstract

Sixty-four tree nut samples (almonds, pecans, pine nuts, and walnuts) and 50 dried fruit samples (apricots, cranberries, papaya, pineapple, and raisins) were purchased from local supermarkets and analyzed for fungal contamination using conventional culture as well as molecular methods. The results of our study showed that the highest yeast and mold (YM) counts (5.34 log10 CFU g−1) were found in walnuts and the lowest in pecans. The most common mold in nuts was Aspergillus niger, relatively low numbers of A. flavus were found across the board, while Penicillium spp. were very common in pine nuts and walnuts. Low levels (2.00–2.84 log10 CFU g−1) of yeasts were recovered from only two pine nut samples. Fungal contamination in dried fruits was minimal (ranging from <2.00 to 3.86 log10 CFU g−1). The highest fungal levels were present in raisins. All papaya samples and the majority of cranberry, pineapple, and apricot samples were free of live fungi. The most common mold in dried fruits was A. niger followed by Penicillium spp. One apricot sample also contained low levels (2.00 log10 CFU g−1) of yeasts.

Quality assessment of goji fruits, cranberries, and raisins using selected markers

“…The previous studies evaluating the occurrence of fungi in dried fruits showed that the main contamination of dried raisins, pineapple, apricots, and cranberries was molds such as Aspergillus sp. and Penicillium sp [34]. In contrary, the results of this study indicated that dried goji fruits were contaminated especially by heat-resistant yeast.…”

“…The potential microbial spoilage during storage and the potential health hazard due to fungal presence and mycotoxins accumulation is one of the most important concerns regarding to dried fruits [31,32]. It has been shown that dried fruits can be contaminated by fungi and their mycotoxins [33,34], and therefore, monitoring is critical for such fruit quality. However, the phenotype microarray method has not previously been described as a tool for the fast detection of mycological contamination, especially for heat-resistant fungi in dried fruits.…”

“…However, the phenotype microarray method has not previously been described as a tool for the fast detection of mycological contamination, especially for heat-resistant fungi in dried fruits. Recent studies [32][33][34] documented the occurrence of high level of mycotoxins or fungal cells in dried fruits including apricots, dates, prunes, figs, and raisins. In contrast to earlier findings, in this study, no evidence of fungi presence in dried raisins was detected.…”

“…The results of dried goji fruits analysis showed contamination at the level of 28 and 23 log 10 CFU g −1 for fungi (yeast and molds) and molds, respectively. The previous research indicated fungal contamination of dried fruits such as apricots, cranberries, pineapple, and raisins; however, there are no data concerning goji fruit contamination by fungi [34]. The community-level physiological profile method was very useful for quick fungal detection in goji fruits, especially for heat-resistant fungi detection.…”

Heat-treatment as a measure for microbiological quality improvement of walnuts and peanuts

“…Indijoje ištyrus 50 graikinių riešutų branduolių, visuose mėginiuose buvo aptikta pelėsinių grybų, kurių koncentracija svyravo nuo 3 iki 5 log 10 ksv/g (Riyaz-Ul-Hassan et al, 2003). JAV visuose 20 tirtų mėginių rasta 2-6 log 10 ksv/g mikromicetų kolonijų (Tournas et al, 2015). Irane taip pat visi graikinių riešutų mėginiai buvo už-teršti pelėsiniais grybais, tačiau ne tokiu dideliu kiekiu kaip kitose šalyse.…”