Issue 2

Abstract not available

Cabbage (Brassica oleracea var. capitata) is one of the major winter vegetables grown in Bangladesh, recognized for its dietary value and economic importance. During November 2023, cabbage leaves exhibiting typical leaf spot symptoms were collected from the Bangladesh Agricultural Research Institute (BARI), Gazipur, to identify the associated pathogen. The infected leaves showed dark brown to black necrotic lesions with concentric rings characteristic of Alternaria leaf spot. The pathogen was isolated on Potato Dextrose Agar (PDA) and purified using a single-conidium isolation technique. Morphological characterization revealed colony and conidial features consistent with Alternaria alternata. To confirm the pathogen identity, molecular characterization was performed using the internal transcribed spacer (ITS) region of rDNA. Amplification with ITS1/ITS4 primers generated a 510 bp fragment, and the resulting sequence was deposited in GenBank under accession number OP585635. Comparison of the obtained sequence against the GenBank database revealed a high degree of homology (99%) with previously deposited A. alternata sequences. The phylogenetic tree also placed the isolate in the same evolutionary group as A. alternata, with 88% bootstrap support. Species-specific PCR using A. alternata-specific primers produced the expected 184 bp amplicon, providing additional confirmation of species identity. Pathogenicity was evaluated using a detached-leaf assay. Leaves inoculated with the fungal isolate exhibited characteristic disease symptoms comparable to those recorded in naturally infected plants, while no symptoms were detected on the control leaves. Following symptom development, the fungus was recovered from infected tissues and its identity was verified using an A. alternata-specific PCR assay, satisfying the requirements of Koch’s postulates. The combined evidence obtained from cultural and microscopic observations, ITS-rDNA sequencing, phylogenetic inference, species-specific molecular detection, and pathogenicity assessment demonstrated that A. alternata was responsible for the leaf spot symptoms observed on cabbage. To our knowledge, this study constitutes the first molecularly confirmed record of A. alternata infecting cabbage in Bangladesh. The information generated will support future disease monitoring efforts and contribute to the formulation of appropriate management practices for sustainable cabbage production.

Mucuna seeds, once largely neglected, are gradually being incorporated into the diets of some communities in Benin because of their high protein content. However, their utilization is constrained by the presence of antinutritional compounds, particularly L-Dopa, which may pose health risks if not adequately reduced during processing. Traditional processors employ various processing methods to detoxify the seeds, but the safety of the resulting foods prepared from different Mucuna varieties has not been fully established. This study aimed to evaluate the L-Dopa and tannin contents of the major traditional Mucuna-based foods in Benin in relation to their processing methods. A total of 84 processors and consumers were interviewed to document Mucuna processing practices and consumption patterns. Subsequently, 10 Mucuna-based food samples were collected and analysed for L-Dopa using the USP–NF 2022, Issue 1 method, while total tannins were determined using the Folin–Ciocalteu method. The results showed that Mucuna processing and consumption were infrequent, occurring mainly once per quarter, with Ata, Afitin, and Abobo being the principal traditional products. Raw white- and black-seeded Mucuna contained 4.6% and 5.0% L-Dopa, respectively. Following processing, L-Dopa contents decreased markedly, ranging from 0.002% to 3.0% depending on the product. Abobo and Afitin contained residual L-Dopa levels below the 1.0% safety threshold, whereas Ata exceeded this limit. Tannin contents in processed products ranged from 0.033 to 0.841 mg tannic acid equivalents/g, indicating substantial reductions following soaking, cooking with water renewal, roasting, and fermentation. Overall, traditional processing methods effectively ensured the safety of Abobo and Afitin, whereas further optimization is required for Ata. These findings provide evidence-based guidance for improving traditional Mucuna processing practices and support the safe utilization of this underutilized legume to enhance dietary diversification and household food security in Benin and similar settings.

Onion paste is a convenient value-added product, but its high moisture content makes it susceptible to physicochemical deterioration and microbial spoilage during storage. This study evaluated the effects of preservative formulation, packaging material, and storage temperature on the physicochemical stability and acidity degradation kinetics of onion paste over eight months. Onion paste was prepared using three formulations: SB (10% salt, 1% citric acid, and 1000 ppm sodium benzoate), KMS (10% salt, 1% citric acid, and 1000 ppm potassium metabisulphite), and CA (1% citric acid), together with a commercially available market sample (MS). Treated samples were packed in plastic and glass containers and stored at room temperature (25 ± 5 °C) and refrigerated temperature (7 ± 2 °C), whereas the market sample was evaluated in its original plastic packaging. Changes in pH, titratable acidity (TA), total soluble solids (TSS), moisture content, and ash content were monitored at two-month intervals. Preservative treatment, packaging material, storage temperature, and storage duration significantly affected (P<0.001) most quality attributes. The pH increased progressively, whereas TA generally declined during storage. The KMS formulation showed comparatively high acidity retention and maintained TSS of 29.36–31.60 °Brix, moisture content of 71.88–73.55%, and ash content of 8.35–8.98%. SB-treated paste maintained TSS of 28.06–29.56 °Brix, moisture content of 71.34–71.97%, and ash content of 8.30–8.50%. In contrast, CA-treated paste showed lower TSS (21.16–24.70 °Brix), higher moisture content (74.08–80.30%), and substantially lower ash content (0.30–0.96%), while the market sample exhibited the lowest TSS (9.10–12.02 °Brix) and highest moisture content (84.10–90.03%). Acidity degradation was evaluated using a first-order kinetic model, although model fit varied considerably among treatment and storage combinations. The KMS-treated paste stored in glass under refrigerated conditions showed the strongest first-order fit (R² = 0.9153) and a predicted acidity half-life of 1.58 years. The combination of potassium metabisulphite, glass packaging, and refrigerated storage provided the most predictable acidity stability among the tested conditions. The findings provide a quantitative basis for optimizing onion-paste preservation and storage practices and demonstrate the potential of kinetic modelling for shelf-life assessment, quality control, and reduction of storage-related losses.