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Penicillium setosum, a member of the Penicillium section Lanata-divaricata, is known for its ability to produce high levels of patulin. However, there is a notable lack of information regarding the influence of environmental factors on the growth and patulin production in fruit juice of this species. In this study, we investigated the impacts of temperature (25, 30, 35, or 40 °C), initial pH value (3, 5, or 7), and incubation time (2, 4, or 6 days) on the growth and patulin production in pineapple juice of the selected P. setosum strain HR9-5. The modified Gompertz model was applied to estimate the maximum growth rate and lag time prior to growth. This strain had the highest growth rate with the shortest lag time within the temperature range 30–35 °C, with an initial pH range of 3–5. Furthermore, it had the greatest biomass dry weight and patulin production at 35 °C with an initial pH of 3, and at 25 °C with an initial pH of 7, respectively. The growth rate and lag time prior to growth of P. setosum HR9-5 were significantly influenced by the initial pH, whereas the biomass dry weight was strongly affected by temperature and incubation time. Additionally, all factors and their interactions had a significant impact on patulin production. This study provided the first report on the effect of environmental factors on growth and patulin production by P. setosum in pineapple juice. These findings can contribute to formulating effective prevention strategies to control the growth of P. setosum and subsequent patulin production in pineapple and other fruit juices.

The contamination and spoilage of heat-treated fruit juices by heat-resistant mold ascospores present significant challenges to the food industry. Understanding effective strategies to mitigate this contamination is vital for ensuring the shelf-life and microbial safety of heat-treated fruit juices. This study investigated the thermal resistance of ascospores from different heat-resistant mold species, including Aspergillus laciniosus, A. chevalieri, A. denticulatus, A. siamensis, Hamigera pallida, and Talaromyces macrosporus, isolated from pineapple and sugarcane field soils. Ascospores inactivation kinetics in pineapple juice under heat treatment (75–97 °C) were analyzed using log-linear and Weibull models. Among these species, A. laciniosus displayed the highest heat resistance (δ-value: 104.59 min at 85 °C), while A. siamensis exhibited the lowest (δ-value: 3.39 min at 80 °C). Furthermore, A. laciniosus, the most heat-resistant species, showed notable tolerance to sanitizers. The most effective inactivation was achieved using 1.0% (w/v) sodium hypochlorite for 15 min. Chlorine dioxide, however, was generally ineffective and even activated dormant ascospores in some cases. The combination of hot water (65 °C for 5 min) with sanitizer increased ascospore reduction in most species but did not achieve the 3-log reduction required by the European Standard N13697. This study revealed a correlation between ascospore resistance to heat and chlorine dioxide, offering significant findings for practical inactivation strategies.

Heat-resistant molds (HRMs) are important spoilage fungi of heat-processed fruit products worldwide. Ascospores of HRMs are widely distributed in the soil in which fruits are grown and are often found associated with raw fruit materials. To date, there is little available information on the distribution of HRMs in the soil and on their heat resistance. Thus, this study determined the presence and characterized the heat resistance of HRMs in soil samples from pineapple and sugarcane fields in Thailand. HRMs were detected in all soil samples, and the most dominant species was Aspergillus with 50–99.2% relative abundance. Other isolates, in descending order of frequency, were Penicillium, Talaromyces, Hamigera, and Paecilomyces. Then, 100 representative HRM isolates were identified based on a combination of morphological characteristics and ITS sequences. They were classified into 5 genera and 24 species. The heat resistance of ascospores aged 30 days produced by selected HRMs was qualitatively determined in a glucose-buffered solution. Based on their log reductions after heat shock at 75°C for 30 min, they were classified as less, moderately, or highly heat-resistant ascospores. HRMs belonging to A. chevalieri, A. denticulatus, A. siamensis, A. laciniosus, A. fennelliae, A. spinosus, Paec. niveus, H. pallida, and T. macrosporus produced high heat-resistant ascospores. In addition, soil physicochemical properties significantly influenced the prevalence of HRMs, depending on the fungal genus. The thermal resistance of ascospores was significantly and positively correlated to available phosphorus, whereas it was negatively correlated to soil pH. The results of this study confirmed the presence of HRMs in soils and potential HRM contamination, especially in fruits growing in acidic or high-nutrient soils, or both.

The recombinant, modified leucine-rich repeat protein rhKU_Sej_LRR_2271 has been suggested as a candidate for leptospiral vaccine development since it was predicted to be a transmembrane protein containing leucine-rich repeat motifs and immunogenic epitopes. The immunogenic epitopes showed binding affinities with lower IC50 values than peptides of known antigenic proteins, e.g., LipL32. Moreover, this protein was immunoreactive with hyperimmune sera against several serovars. In this study, we aimed to develop a lateral flow strip test using the rhKU_Sej_LRR_2271 protein for the detection of anti-leptospiral IgG in dogs. The lateral flow assay was performed with 184 dog plasma samples and evaluated with a culture method, 16S ribosomal RNA gene (rss) analysis real-time PCR, and LipL32 ELISA. The culture method failed to detect leptospires in the dog blood samples. Six of nine symptomatic dogs gave positive results with the real-time PCR assay. The lateral flow assay and LipL32 ELISA gave positive results with 59 and 50 dogs, respectively. The sensitivity, specificity, and accuracy of the rhKU_Sej_LRR_2271 lateral flow strip test were 70.00, 82.09, and 78.80%, respectively, when compared with LipL32 ELISA. There was a significant association between the LipL32 ELISA and the rhKU_Sej_LRR_2271 lateral flow assay. The rhKU_Sej_LRR_2271 lateral flow strip test has therefore demonstrated a good potential to detect anti-leptospiral IgG in dogs.

Domestic and stray dogs can be frequently infected by Leptospira, and thus may represent a source for transmission of this zoonotic disease in Thailand. Here, we have used peptides derived from a recombinant leucine-rich repeat (LRR) protein of Leptospira, rKU_Sej_LRR_2012M, for the development of an indirect enzyme-linked immunosorbent assay (ELISA) aimed at detecting antibodies against Leptospira interrogans, L. borgpetersenii, and L. biflexa, the three major seroprevalences in Thai dogs. The rKU_Sej_LRR_2012M protein is recognized by hyperimmune sera against several leptospiral serovars. The epitope peptides of the rKU_Sej_LRR_2012M showed binding affinities with lower IC50 values than peptides of known antigenic protein LipL32. Four peptides, 2012-3T, 2012-4B, 2012-5B and pool 2012-B, were specifically recognized by rabbit hyperimmune sera against nine serovars from three Leptospira spp. The indirect peptide-based ELISAs with these four peptides were evaluated with the LipL32 ELISA by using a receiver–operator curve (ROC) analysis. All peptides had an area under the curve of ROC (AUC) greater than 0.8, and the sum of sensitivity and specificity for each peptide was greater than 1.5. The degree of agreement of 2012-3T and pool 2012-B and 2012-4B and 2012-5B peptides were in moderate-to-good levels with kappa values of 0.41–0.60 and 0.61–0.80, when compared with LipL32, respectively. This finding would suggest an excellent capability of the 2012-4B and 2012-5B peptide-based ELISAs assay for the diagnosis of canine leptospiral infections.

In-house immunoaffinity column for aflatoxins (AFs) detection is firstly developed by Kasetsart University since 2011 i.e. the first IAC prototype, KU-AF01. Detection of aflatoxin B1 (AFB1) up to 200 ng is considered significantly efficient, but the production cost is considered high. The high cost was due to the cost of monoclonal antibody specific to aflatoxin and its supporting materials i.e. CNBr-activated sepharose 4B. Therefore, this study was aimed to improve the efficiency of in-house immunoaffinity colums by replacing CNBr-activated sepharose 4B with other supporting materials and to lower the ratio of antibody to supporting materials.  Response surface methodology (RSM) was applied to determine the optimum alternative supporting materials and the ratio. Results revealed that when compared with CNBr-activated sepharose 4B, all materials tested could recover higher than 80% AFB1, except the activated CH sepharose 4B. Results also indicated that the optimum ratio was 0.4 mg anti-aflatoxin monoclonal antibody to 204 µL CNBr-activated sepharose 4B. CNBr-activated sepharose 4B was considered to provide the best precision in recovering AFB1. KU-AF02 increased the ability to detect AFB1 to 500 ppb. The recovery of AFs in the reference materials using KU-AF02 was more than 96% successful, with HorRat value range of 0.34 – 0.76. The reference materials used were 2 levels of AFs in peanuts, i.e. 47.68 and 72.14 ng/g. In terms of quality control in IAC production, there were no significant differences among the 5 batches produced (p > 0.05). KU-AF02 demonstrated stable and constant percent recovery at 4 oC for up to 12 months (tested with standard 200 ppb AFB1). This study indicated that KU-AF02 could lower the ratio of supporting materials to the antibody and that KU-AF02 has high stability and has good ability for cleaning up AFs. Therefore, KU-AF02 is recommended to be used as an in-house immunoaffinity column for aflatoxin detection in Thailand.

Aflatoxins (AFs) and aflatoxin B1 (AFB1) intake through consumption of peanuts and peanut products were estimated from 60 samples. The samples were collected from 2 retail and 2 wholesale markets in Bangkok during November 2013–January 2014. The results showed that 80% of raw peanut samples were contaminated with AFs while 100% of roasted and ground peanuts samples were contaminated. The highest concentration of AFs was found in ground peanuts at 362.48 ng g−1 resulting in the highest mean concentration (68.22 ng g−1). According to a food consumption database, the average intake of AFs was estimated at 0.49, 0.40 and 2.13 ng/kg bw/day for raw, roasted and ground peanuts, respectively. The potential risk for cancer was estimated at 0.01–0.12 cancer/year/100,000 persons. The results suggest that the current situation of aflatoxins contamination in peanuts and peanut products (especially in ground peanuts) has an adverse effect on the health of the Thai population.