Alternative Green and Novel Postharvest Treatments for Minimally Processed Fruits and Vegetables

Minimally processed fresh produce is ready to eat and subjected to minimal technology before consumption. Fresh fruits and vegetables (FFVs) are minimally processed commodities that are metabolically active and undergo physiological processes such as ripening and senescence, reducing their quality and shelf life. Postharvest technologies maintain the quality and prolong the shelf life of harvested produce, without which the quality deteriorates such that significant economic loss ensues due to water and nutrients loss, physiological deterioration, biochemical changes, and microbial degeneration. Conventional postharvest treatments such as temperature management, and chemical and gaseous treatments are widely known for controlling postharvest issues in FFVs. However, there are novel and green alternative safe methods that are employed to maintain the postharvest quality and prolong the shelf life of FFVs. This chapter focuses on seven common alternative novel and green postharvest treatments: nitric oxide, ozone, methyl jasmonate, salicylic acid, oxalic acid, calcium, and heat treatments. These treatments are explained and some of their current application on FFVs are discussed and tabularized indicating the optimum treatment conditions reported in the latest scientific publications

Evidence of the effect of pre and postharvest practices on aflatoxin contamination in the Forest and Savannah ecozones of Ghana

Food contamination by aflatoxins is a global concern due to their adverse effects on food security, trade, and health. This study contributes to the evidence on the connection between pre and postharvest practices of maize farmers and the levels of aflatoxin contamination, based on a survey of 400 farmers across Forest and Savannah zones in Ghana. The survey involving a semi-structured questionnaire was conducted between September 2019 and March 2020. Information on preharvest practices such as weed control, fertilizer application, and irrigation; and postharvest practices such as drying, shelling, storage, and pest control among others were explored by the questionnaire. A multistage sampling process was employed to determine the sample size of four hundred respondents. One kg of maize was randomly sampled from the farmers for aflatoxin analysis. The results showed that the least aflatoxin type found in the maize sample was Aflatoxin G2 (0.207 μg/kg), while the highest was Afltoxin B1 (9.618 μg/kg). The Savannah zone recorded a lower contamination level of 11.63 μg/kg than the Forest zone of 23.53 μg/kg. Aflatoxin G1 and Aflatoxin G2 were less prevalent among the samples than Aflatoxins B1 and B2. The contamination levels in both zones exceeded the maximum limits, set by Codex, and EU at 10 μg/kg, and 4 μg/kg respectively. Only the Savannah zone contamination level met the maximum limit of contamination of Ghana which is set at 15 μg/kg. About 73% of farmers who demonstrated awareness of aflatoxin contamination had their produce within the maximum limit of Ghana, CODEX, and the EU. Preharvest practices such as fertilizer application, hoeing, and chemical weed control lowered aflatoxin contamination in both zones. The results showed that awareness creation and adoption of pre and postharvest interventions are vital in reducing aflatoxin contamination in the two ecozones

Impact of extraction parameters and their optimization on the nutraceuticals and antioxidant properties of aqueous extract mulberry leaf

An investigation into the efficient use of water as a solvent and the influence of extraction temperature, extraction time, water to leaf powder ratio, particle size, and extraction cycle on the nutraceutical and antioxidant profile of aqueous mulberry leaf extract were conducted using a single-factor experiment approach. All the assessed extracting parameters showed a significant effect on the nutraceutical compounds and antioxidant properties. The optimum extraction conditions were as follows: extraction temperature of 70°C, extraction time of 40 min, water to leaf powder ratio of 40:1 ml/g, particle size of 25 µm, and two extraction cycles. Based on these optimal conditions, chlorogenic acid (62.10 mg/g), caffeic acid (32.21 mg/g), kaempferol-7-O-glucoside (19.30 mg/g), quercetin-3-rutinose (15.69 mg/g), quercetin-3-O-glucoside (32.38 mg/g), kaempferol-3-(6-rhamnosylglucoside) (42.52 mg/g), quercetin-3-(6-malonylglucoside) (65.19 mg/g), kaempferol-3-glucoside (66.27 mg/g), kaempferol-3-(6-malonylglucoside) (50.18 mg/g), 1-deoxynojirimycin (15.58 mg/g), and gamma-aminobutyric acid (5.05 mg/g) were obtained. The optimal aqueous extract had high antioxidant properties of 2,2-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (39.98 mM/g), cupric ion reducing capacity (58.93 mM/g), 1,1-diphenyl-2-picrylhydrazyl (101.33 mM/g), and ferric reducing antioxidant power capacity (233.77 mM/g) of dried mulberry leaf extract

The Possible Mechanisms Involved in Degradation of Patulin by Pichia caribbica

In this work, we examined the mechanisms involved in the degradation of patulin by Pichia caribbica. Our results indicate that cell-free filtrate of P. caribbica reduced patutlin content. The heat-killed cells could not degrade patulin. However, the live cells significantly reduced the concentration of the patulin. In furtherance to this, it was observed that patulin was not detected in the broken yeast cells and cell wall. The addition of cycloheximide to the P. caribbica cells decreased the capacity of degradation of patulin. Proteomics analyses revealed that patulin treatment resulted in an upregulated protein which was involved in metabolism and stress response processes. Our results suggested that the mechanism of degradation of patulin by P. caribbica was not absorption; the presence of patulin can induce P. caribbica to produce associated intracellular and extracellular enzymes, both of which have the ability to degrade patulin. The result provides a new possible method that used the enzymes produced by yeast to detoxify patulin in food and feed

Protein Expression Profile and Transcriptome Characterization of Penicillium expansum Induced by Meyerozyma guilliermondii

Antagonistic yeasts can inhibit fungal growth. In our previous research, Meyerozyma guilliermondii, one of the antagonistic yeasts, exhibited antagonistic activity against Penicillium expansum. However, the mechanisms, especially the molecular mechanisms of inhibiting activity of M. guilliermondii, are not clear. In this study, the protein expression profile and transcriptome characterization of P. expansum induced by M. guilliermondii were investigated. In P. expansum induced by M. guilliermondii, 66 proteins were identified as differentially expressed, among them six proteins were upregulated and 60 proteins were downregulated, which were associated with oxidative phosphorylation, ATP synthesis, basal metabolism, and response regulation. Simultaneously, a transcriptomic approach based on RNA-Seq was applied to annotate the genome of P. expansum and then studied the changes of gene expression in P. expansum treated with M. guilliermondii. The results showed that differentially expressed genes such as HEAT, Phosphoesterase, Polyketide synthase, ATPase, and Ras-association were significantly downregulated, in contrast to Cytochromes P450, Phosphatidate cytidylyltransferase, and Glutathione S-transferase, which were significantly upregulated. Interestingly, the downregulated differentially expressed proteins and genes have a corresponding relationship; these results revealed that these proteins and genes were important in the growth of P. expansum treated with M. guilliermondii

Screening of Deoxynivalenol Producing Strains and Elucidation of Possible Toxigenic Molecular Mechanism

In this study, seven strains of Fusarium graminearum were isolated from wheat, of which six were identified to produce deoxynivalenol and the production of deoxynivalenol was assessed. F. graminearum strain Fg1 was noted to produce 1.0 μg/g deoxynivalenol during the incubation period in the Czapek yeast broth, while none was detected in F. graminearum strain Fg2. Hence, the differences in proteomes and transcriptomes of Fg1 and Fg2 were compared to analyze the mechanism underlying deoxynivalenol production. Among the 66 significantly differentially expressed proteins in Fg1, 39 and 27 were more or less abundant expressed. Functional analysis suggested that the enzymes involved in the methylerythritol 4-phosphate and mevalonate pathways, which provide a substrate for biosynthesis of farnesyl pyrophosphate, a precursor of DON, were activated in Fg1. The transcriptomics data demonstrated that the expression level of a majority of genes, including trichothecene biosynthetic genes, protein kinases, and transcription factors, involved in trichothecene biosynthesis was higher in Fg1 than in Fg2. The results also revealed differential expression profiles of deoxynivalenol biosynthesis genes in strains Fg1 and Fg2, which emphasized their deoxynivalenol producing ability and the underlying mechanism