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Control of Microbial and Mycotoxins Contamination in Agricultural Commodities During Post-Harvest Handling Processes
The contamination of microorganism and mycotoxins in agricultural commodities can occur in every step of handling processes either pre-harvest or post-harvest. The control measure of contaminations was start-up by investigation of causal of contamination during production processes. Our researchers conducted the research project “Control of Microbial and Mycotoxins Contamination in Agricultural Commodities During Post-Harvest Handling Processes” the fiscal year 2015-2017, with the objective was "to studies on contamination of pathogenic fungi, mycotoxin producing fungi and mycotoxins in processes and methodology of crop productions for the scientific information those capable used for setting up the guide line of postharvest contamination control measure in production system" The project consisting of 7 experimental under 2 activities, first activity is “Microbial Contamination Agricultural commodities” and the second activity is “Mycotoxin Contamination of Agricultural commodities” The results of those experiments are the following.
The first experiment is “Studies on Postharvest Loss in Tangerine (Lonicera japonica Thunb) from Penicillium spp.” This research aimed to Studies on Postharvest Loss in Tangerine (Lonicera japonica Thunb) from Penicillium spp. The research was handled between October 2014 and September 2016 at Chaingmai Province and Postharvest and Processing Research and Development Division. This research was divided 2 parts: Frist was study on the production of Tangerine from the orchard to the packinghouse. The result show that postharvest losses of the orchard causes by many factors such as natural disaster, harvesting and transportation. Moreover, the farmers against treated Tangerine trees with antibiotic. Ampicillin and Amoxy were applied at 15 g/L of water by injected into the trees. There is no postharvest loss caused by fungi on Tangerine fruits. Second, study on the losses and identification of pathogens from the orchard to the packinghouse. Postharvest loss of orchard was a main cause of packinghouse loss such as it was initiated the appeal of fruit rot and the pathogens infection in open wound. This symptom was violently when the Tangerine were storage for long time. In the conclusion, selection of Tangerine had wound and was bruise after harvesting from tree. It was a protection of the appeal of fruit rot and the pathogens infection of Tangerine storage in distribution of the customer. The causal pathogens of Tangerine were Fusarium spp, Cladosporium sp., Aspergillus spp and Penicillium spp. The result indicated that finding the activity of toxin production of Aspergillus spp and Penicillium spp. in Tangerine.
Second experiment is “Study on Flower Rusty Spots Contaminate of Curvularia sp. In Dendrobium Hybrid Postharvest” Flower rusty spot caused by Curvularia eragrostidis is the most important problem of Dendrobium orchids after harvest. Epidemic cause and factor affecting epidemic was studied in 5 cultivar such as Den.Kho Jiranand, Den.White Fairy, Den.Sonia ‘Jo Daeng’, Den.Sonia ‘Earsakul’. The study was carried out in 21 orchid farms of
4 provinces including Bangkok, Nakhon Pathom, Nonthaburi and Samut Sakhon, and
11 samples from flower market (Pakklong Talad) from June to July 2015. We found that the major caused disease was C. eragrostidis from Nakhon Pathom farm accounting for 66.67%, then Bangkok, Nonthaburi and Samut Sakhon, respectively. Furthermore, it was found in weed accounting for 6.67% but not in planting material, water, and soil. Surprisingly, antagonistic fungi called Trichoderma spp. was found in these materials for 73 isolates. Then the 3 efficient isolates were selected to control disease both in vitro and in vivo. However, we found no
C. eragrostidis from flower market, but we found other caused diseases such as Alternaria sp., Colletotrichum sp., Fusarium sp., and Cladosporium sp., etc. The biological control of in vitro test showed that T03 and T02 inhibited C. eragrostidis mycelium growth for 40.83 and 34.40% respectively at 30?C and filled PDA within 5 days whereas iprodione 50%WP showed 100% inhibition. The in vivo test showed that Trichoderma spp. isolate T03 had the most efficiency to control disease in every temperature since disease percentage of Den. Kho Jiranand kept at 20, 5, and 10?C was 0.35, 0.40, and 0.40 respectively comparing with control and iprodione 50%WP at 0.85 and 0.20 at 5?C respectively.
The third experiment is “Guidelines for Contamination Control and Reduction of Ochratoxin A in Chilli.” Ochratoxin A (OTA) is a toxin causing kidney cancer produced by some species of fungi, e.g. Aspergillus flavus and A. niger. The contamination of OTA is often found in feed and food including chilli. This research examined the situation of OTA contamination in dried chilli from major production areas in Thailand and determined the method to reduce OTA for enhancing food safety and quality. The data of dried chilli productions were collected from 3 provinces (Nakhon Ratchasima, Ubon Ratchathani and Chaiyaphum). Contaminated toxigenic fungi was observed by direct plate count method and OTA concentrations were analyzed by fluorometry. OTA contaminations were detected in 42 of 87 samples (48.28%) with level between 0.1 and 9.8 ?g/kg. The highest OTA amount was detected in sample from Chaiyaphum province at 65 ?g/kg. This concentration exceeds maximum level of the European Union (15 ?g/kg). A. niger was the major toxigenic fungi contaminated in dried chilli from Chaiyaphum province (44.91%), followed by A. flavus 32.45% and A. ochraceus 2.64%. Randomized Complete Block design was applied for 2 experiments of toxin reduction with
3 replications. Six groups of dried chilli were treated at 70 and 80oC for 30, 45 and 60-minute OTA concentration of dried chilli treated at 80oC for 60 minutes decreased by 77.71% comparing to non-treated chilli (control group).
The forth experiment is “Study on Control of Patulin Contamination in Agricultural Commodities and Processing Products.” The inspection of fungal and fungal contamination in agricultural commodities and processing products was conducted leading to be a guideline for setting of control measure. The inspection was conducted at the postharvest disease laboratory, Postharvest and Processing Products Research and Development Division, Department of Agriculture, during the fiscal year 2558-2559. Twelve types of processed fruit products, 338 samples in total, were detected for fungal contamination and 41 samples or 12.13 in percentage were contaminants. It was found that the dried Bael fruit (Aegle marmelos (L.) Corr?a) was most contaminated with fungi by 28 samples from 28 specimens, or 100 in percentage. Although there was no patulin contamination in all dried Bael fruit’s specimens but highly of fungal contamination revealed that there was risk of contamination from the other mycotoxins. One hundred and ninety-two specimens of 15 species of the importing fresh fruits pass through Chiang Saen checkpoint, Chiang Rai province was collected, and resulted all specimens were contaminants by fungi. Twenty-eight samples of dry fruit and fruit juices were tested by the laboratory of Central Laboratory (Thailand) there was no patulin contamination.
The fifth experiment is “Study on Contamination Control of Fungi and Aflatoxin B1 in Pepper.” Study on contamination control of fungi and aflatoxin B1 in pepper was to reduce the risk of fungi and aflatoxin B1 contamination. One hundred and seventy-four samples of pepper product were tested in this study. The white pepper was contaminated with Aspergillus flavus at 0.0-13.2%, but not found the fungi in white powder pepper. The contamination of aflatoxin B1 was analyzed by an enzyme-linked immunosorbent assay (ELISA) technique. Aflatoxin B1 contamination was detected in white pepper and white powder pepper at
0.0- 16.2 and 0.0- 12.4 ?g/kg, respectively. A. flavus content was found in black pepper with 7.1-8.0%, but not found in black powder pepper. Aflatoxin B1 were detected in black pepper and black powder pepper at 0.0-18.5 and 6.4-59.1 ?g/kg, respectively. The contaminations of fungi and aflatoxin B1 in white pepper during the production processing, the highest A. flavus was contaminated at 37% and aflatoxin B1 was detected at 4.21 ?g/kg in the incubation process for 5 days. To produce black pepper, samples from sun dried process for 2 days was contamination with A. flavus at 3.0% and aflatoxin B1 content at 5.78 ?g/kg. Thus, the recommendation for production of white pepper avoided the incubation in plastic bag and should be dried by sun suddenly after removing the outer skin. Black pepper production should be dried by sun after harvesting, use clean pad drying and avoided placing pepper on ground directly. This method will reduce contamination of fungi and aflatoxin B1 in pepper.
The sixth experiment is “Study on Fungal and Mycotoxins Contamination in Coffee and Product.” Study on fungal and analysis of Ochratoxin A (OTA) and Aflatoxin B1 (AFB1) contamination in coffee that grown and consumed in Thailand. The purpose of this study was to evaluate the situation of mycotoxin contamination in coffee bean and coffee product during 2014 and 2016 cultivation seasons. Sixty samples, three types of coffee beans, dried cherries, parchment coffee, green bean were collected from the farms and markets in Chiangmai, Chiangrai, Mae Hong Son, Tak, Lampang, Chumphon and Ranong. Post-harvest fungi were enumerated by direct plating whereas OTA and AFB1 were analyzed by ELISA. The result showed that coffee drying process had high percentage of Aspergillus toxigenic species, 100% belonging to Aspergillus niger, 14.93% belonging to A. ochraceus and 8.29% belonging to
A. flavus. Among those contaminated samples, there were 6% of total samples contained amount of AFB1 higher than 20 microgram/kilogram (ppb) at maximum levels 63.10 ppb, while 13% of total samples contained amount of OTA higher than 20 ppb at maximum levels 56.05 ppb. Fifty-four samples, three types of coffee products, roasted coffee, traditional roasted coffee and instant coffee were analyzed for mycotoxins contamination by HPLC. The results showed that three samples of coffee products were contaminated with AFB1, and the samples were found to be positive AFB1 for the first time in Thailand, although their levels were low for consumer’s safety consumption.
The seventh experiment is “Study on the controlling of fungi and mycotoxin contamination in fresh grape and product.” The contamination of fungi and ochratoxin A was studied in grape product including 24, 7 and 14 samples from raisin, grape juice and wine, respectively. The black raisin imported from foreign countries was divided into 2 parts packed in the box and distributed in a bag in Thailand. We found that 100% of Aspergillus niger was contaminated in both box and bag and 60 and 50% of Eurotium sp. was contaminated in both box and bag, respectively whereas the contamination of the black raisin imported and packed in foreign countries was 50% of Eurotium sp. and then 25% of A. niger and Penicillium sp. There was no contamination in golden raisin, grape juice and wine. The ochratoxin
A contamination was inspected by ELISA. We found that the ochratoxin A in black raisin, golden raisin, grape juice and wine was 2.13-23.33, 3.07-9.93, 1.53-4.63 and 1.87-4.83 ?g/kg., respectively. Then we studied the contamination of fungi and ochratoxin A from orchard in 4 stages of growth development We found that the ochratoxin A of the first stage (30-40 days after fruit set) and the second stage (60-70 days after fruit set) of every orchard was ranged 7.95-11.90 ?g/kg. and Alternaria sp., Cladosporium sp. and A. aculeatus were also contaminated in these stages. The ochratoxin A of the third stage (90-100 days after fruit set) and the fourth stage (120 days after fruit set) of every orchard was ranged 2.90-20.3 ?g/kg. Moreover, we found that Penicillium sp., A. aculeatus and Alternaria sp. were also contaminated in these stages. When we inspected the environment of planting field we found that A. aculeatus and Penicillium sp. were high in soil and air. Therefore, the good management from planting to harvest was important to reduce fungi and ochratoxin A. |
