As a filamentous and spoilage fungus, Alternaria spp. can not only infect processing tomatoes, but also produce a variety of mycotoxins which harm the health of human beings. To explore the production of Alternaria toxins in processing tomatoes during growth and storage, four main Alternaria toxins and four conjugated toxins were detected by ultrahigh-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) and ultra-performance liquid chromatography-ion mobility quadrupole time-of-flight mass spectrometry (UPLC-IMS QToF MS) in processing tomatoes on different days after being inoculated with A. alternata. The results show that the content of Alternaria toxins in an in vivo assay is higher than that under field conditions. Tenuazonic acid (TeA) is the predominant toxin detected in the field (205.86~41,389.19 μg/kg) and in vivo (7.64~526,986.37 μg/kg) experiments, and the second-most abundant toxin is alternariol (AOH). In addition, a small quantity of conjugated toxins, AOH-9-glucoside (AOH-9-Glc) and alternariol monomethyl ether-3-glucoside (AME-3-Glc), were screened in the in vivo experiment. This is the first time the potential of Alternaria toxins produced in tomatoes during the harvest period has been studied in order to provide data for the prevention and control of Alternaria toxins.

Large amounts of processing tomato are grown in Xinjiang, China. Tomato black spot disease, caused by Alternaria spp., and the produced alternaria toxins in tomato products are posing risks to human health. In this study, we isolated a rhizospheric bacterium, XJ-BV2007, from tomato (Solanum lycopersicum) fields, which we identified as Bacillus amyloliquefaciens. We found that this bacterium has a strong antagonistic effect against Alternaria alternata and reduces the accumulation of alternaria toxins in tomatoes. According to the antifungal activity of the bacteria-free filtrate, we revealed that B. amyloliquefaciens XJ-BV2007 suppresses A. alternata by the production of antifungal metabolites. Combining semi-preparative high-performance liquid chromatography, we employed UPLC-QTOF-MS analysis and the Oxford cup experiment to find that fengycin plays an important role in inhibiting A. alternata. This paper firstly reported that B. amyloliquefaciens efficiently controls tomato black spot disease and mycotoxins caused by A. alternata. B. amyloliquefaciens XJ-BV2007 may provide an alternative biocontrol strain for the prevention of tomato black spot disease.

Alternaria spp. and its toxins are the main contaminants in processing tomato. Based on our earlier research, the current study looked into the anti-fungal capacity of crude lipopeptides from B. amyloliquefaciens XJ-BV2007 against A. alternata. We found that the crude lipopeptides significantly inhibited A. alternata growth and reduced tomato black spot disease incidence. SEM analysis found that the crude lipopeptides could change the morphology of mycelium and spores of A. alternata. Four main Alternaria toxins were detected using UPLC-MS/MS, and the findings demonstrated that the crude lipopeptides could lessen the accumulation of Alternaria toxins in vivo and in vitro. Meanwhile, under the stress of crude lipopeptides, the expression of critical biosynthetic genes responsible for TeA, AOH, and AME was substantially down-regulated. The inhibitory mechanism of the crude lipopeptides was demonstrated to be the disruption of the mycelial structure of A. alternata, as well as the integrity and permeability of the membrane of A. alternata sporocytes. Taken together, crude lipopeptides extracted from B. amyloliquefaciens XJ-BV2007 are an effective biological agent for controlling tomato black spot disease and Alternaria toxins contamination.

Patulin (PAT) is a toxic secondary metabolite produced by Aspergillus sp. and Penicillium sp., which acts as a contaminant of most apples and their products. The internationally recognized HACCP system is selected as the theoretical basis to more effectively reduce the PAT in apple juice concentrate (AJC). Through field investigation of apple juice concentrate (AJC) production enterprises, we collected 117 samples from 13 steps of AJC production, including whole apple, apple pulp, and apple juice. PAT contents were analyzed via high-performance liquid chromatography (HPLC) and compared with samples from the different production processes. The result demonstrated that the PAT content was significantly (p < 0.05) influenced by five processes, receipt of raw apples, sorting of raw apples, adsorption step, pasteurization, and aseptic filling. These processes were determined as the CCPs. Monitoring systems for maintaining CCPs within acceptable limits were established, and corrective actions were proposed in case a CCP was surpassed. Based on the above-identified CCPs, critical limits, and control methods (corrective actions), a HACCP plan related to the production process of AJC was established. This study provided important guidance for juice manufacturers wishing to effectively control the PAT content in their products.

Healthy, nutritious, and delicious mulberry wine is loved by everyone, but there is no specific yeast for mulberry wine. To screen for yeasts with low-yield higher alcohols for the fermentation of mulberry wine, we tested five commonly used commercial yeasts available on the market to ferment mulberry wine. All five yeasts were able to meet the requirements in terms of yeast fermentation capacity, speed, and physical and chemical markers of mulberry wine. The national standards were met by the fermentation requirements and the fermented mulberry wine. We identified yeast DV10 as a yeast with low-yield higher alcohols suitable for mulberry wine fermentation. The total higher alcohol content in fermented mulberry wine was 298 mg/L, which was 41.9% lower than that of fermented mulberry wine with yeast EC118. The contents of 17 free amino acids and five sugars in mulberry juice and five yeast-fermented mulberry wines were tested. The results showed that the higher the amino acid and sugar content in yeast-fermented mulberry wine, the higher the content of higher alcohols produced by fermentation. A correlation analysis performed on each higher alcohol produced when yeast DV10 fermented the mulberry wine indicated decreased sugar and related amino acids. The findings demonstrated a substantial negative correlation among the levels of increased alcohol, decreased sugar, and matching amino acid content. Considering the correlation values among increased alcohol, decreased sugar, and related amino acids, the very slight difference suggests that both sugar anabolism and amino acid catabolism pathways have an equivalent impact on the synthesis of higher alcohols during the fermentation of mulberry wine. These results provide a theoretical basis for reducing the content of higher alcohols in mulberry wines, given the history and foundation for producing mulberry wine.

Volatile flavor has prompted a great amount of influence in acceptance and view points in fruit products. Melon (Pyrus communis) is an aroma-dense fruit, thus, the evaluation of volatile flavor is crucial to melon-breeding. The volatile compounds present in nine varieties of Xinjiang muskmelons were identified and analyzed using the headspace solid-phase microextraction and gas chromatography-mass spectrometry methods. In addition, transcriptomics were used to discover the differential genes in fatty acid degradation pathways. It was found that a total of 170 volatile substances, including 52 alcohols, 41 esters, 24 aldehydes, 32 ketones, 14 acids and seven phenols, were identified in the nine melons. Results of PCA showed that 3-nonanol, 2-nonanol, bis (2-ethylhexyl) adipate, and 2-methylpropanal contributed more to the flavor of melon. It was verified that high activities of acyl-coenzyme A cholesterol acyltransferase (AAT) promoted the conversion of alcohols to esters, so that the melons have a high content of esters. Four genes of long-chain acyl-CoA synthetase were mainly responsible for the large difference in volatile substances. This practice may further undermine the primary rationale for the breeding and promotion in different cultivars of muskmelon.