International Journal of Food Science

The fermentation of sweet potato (Ipomoea batatas L.) with a strain of Lactobacillus plantarum leads to an increase in its exopolysaccharides (EPS) content which is useful for enhancing the functional properties of flour. The objective of this study was to develop healthy and nutritious meal-based biscuits from fermented sweet potato (FSP) flour supplemented with mackerel flour. Eleven formulations containing wheat flour, FSP flour, nonfermented sweet potato (NFSP) flour, and mackerel flour at different proportions defined following a mixture design were used to prepare biscuits. Physicochemical, microbiological, and sensory analyses of the different biscuits were performed. Biscuits prepared with FSP at 100% scored the lowest lipid () and the highest sugar () contents. The incorporation of mackerel flour in the formulation led to a significant () increase in the protein and mineral contents of biscuits thus conferring an immune-boosting property to these latters. All the biscuits were of good microbiological quality independent of the formulation. The highest DPPH free radicals scavenging activity (IC₅₀ of 1.90 and 3.41 μg/mL for ethanolic and methanolic extracts, respectively) were observed with biscuits prepared with FSP flour at 100%. The sensorial characteristics of biscuits prepared with equal proportions of wheat and FSP flours were highly appreciated by the panelists with scores close to the ones prepared with wheat flour at 100%. The results of this study demonstrate the potential of FSP flour as a substitute for wheat flour in biscuits preparation. It also suggests biscuits prepared with FSP flour supplemented with mackerel flour as a functional and immune-boosting food.

Tomato (Lycopersicon esculentum) is an important vegetable used in cooking most local foods in Ghana. At the peak season of harvesting, high loses are incurred because of the absence of tomato processing facilities to store, process, and extend the shelf life of fresh tomatoes. Solar drying has been proven to be a more efficient and low-cost method of enhancing quality and adding value to tomato and other vegetables. However, there are concerns about the functionality and quality of the dried products by consumers due to the methods of drying used. In this study, a passive mixed-mode solar dryer suitable for drying tomato was adapted and used to investigate the dehydration characteristics and microbiological quality of the dried tomato. The efficiency of a passive solar dryer was evaluated and used in the processing of fresh tomato to powder. The processing involved the pretreatment of 6 mm slices of fresh Roma variety of tomato by dipping in potassium metabisulfite solution and ascorbic acid solution. The moisture content, moisture ratio, and dehydration rate of solar-dried tomato were assessed. The 24 h dryer efficiency of 24.2% facilitated the drying process of tomato (final moisture content of 12-14%). Aerobic mesophile counts were lower in solar-dried tomato pretreated with potassium metabisulfite (3.90 CFU/g) compared with sun-dried samples (4.85 CFU/g). Solar-dried tomato powder is safer for consumption compared with open sun-dried tomato samples.

Moisture sorption isotherms of five sweet cherry cultivars (Prunus avium L.) at three temperatures of 30°C, 40°C, and 50°C, and water activity range of 0.057–0.898 were determined using the static gravimetric method. The sorption isotherms of all cultivars decreased with increasing temperature, and they all exhibited type II behavior according to the classification of IUPAC (International Union of Pure and Applied Chemistry). The isosteric heat of sorption, differential entropy, spreading pressure, and water surface area were determined, and the energy associated with the sorption processes was defined. The curves were fitted to GAB, PELEG, and ENDERBY models, and the GAB model gave the best fit for the whole set of data. The enthalpy–entropy compensation proved that the process occurs spontaneously and is fully controlled the enthalpy. The spreading pressure value varied with temperature in all sweet cherry cultivars in both the desorption and adsorption processes. The average surface area varied from 78.05 to 214.02 m²/g for desorption and from 49.0 to 204.4 m²/g for adsorption from 30 to 50°C.

The thermal behavior of mopane worms (Imbrasia belina), roasted peanuts (Arachis hypogaea L.), and sweet corn (Zea mays L. saccharata) was investigated under inert conditions using the TGA-FTIR analytical technique heated from 64 to 844°C at a heating rate of 20°C/min. The degradation patterns of the food samples differed as sweet corn and peanuts exhibited four degradation stages 188, 248, 315, and 432°C and 145, 249, 322, and 435°C, respectively. Mopane worms displayed three (106, 398, and 403°C). The different decomposition patterns together with the types of evolved gases shown by FTIR analysis justified the varied biochemical and chemical composition of foods. The common evolved gas species between the food samples were H₂O, CO₂, P=O, CO, and CH₄ but mopane worms showed two extra different bands of C-N and N-H. Higher volumes of evolved gases were recorded at temperatures between 276 and 450°C, which are higher than the usual cooking temperature of 150°C. This means that the food maintained its nutritional value at the cooking temperature. Mopane worms were found to contain twice and four times crude protein content than peanuts and corn, respectively. Only total arsenic metal was reported to be above threshold limits.

Several natural preservative techniques including plant extracts are used to minimize postharvest losses caused by pathogens. Our recent findings elucidated that the application of crude extracts of ginger, turmeric, and “dukung anak” (Phyllanthus niruri Linn.) alone causes phytotoxicity and adversely affects the postharvest quality of dragon fruit, especially at high concentrations. This study investigated the effect of a composite coating of 10% gum arabic (GA) and crude extracts of ginger, turmeric, and “dukung anak” separately at 5, 10, and 15 g L^-1 on postharvest quality of dragon fruit stored at , 80% RH for 28 days. After 28 days of cold storage, anthracnose was significantly reduced in fruit coated with 10% GA plus 10 or 15 g L^-1 of any of the crude extracts and resolved the problem of phytotoxicity while maintaining the postharvest quality of fruit for 28 days. The reduction of anthracnose was pronounced at 10% GA+10 g L^-1 of turmeric extract (38.6%) which was not significantly different at 10% GA+10 g L^-1 of ginger extract compared to control (41.3%). Composite coating of 10% GA+10 g L^-1 of turmeric extract maintained the postharvest quality of dragon fruit as was evident with a reduction in weight loss (2.53%), delayed degradation of titratable acids (0.15%), and maintained fruit firmness (28.72 N) and the overall acceptability of the fruit after 28 days. We conclude that incorporation of 10% GA with turmeric extract at a high concentration can serve as a potential biofungicide in postharvest management of fresh produced by reducing phytotoxicity while improving the overall acceptability of fruit.

Functional foods such as mushrooms are rich in polyphenolic compounds and secondary metabolites with health-promoting properties such as antioxidant, antimicrobial, antidiabetic and immunostimulatory effects. The present study is aimed to investigate the ethanolic extracts of three varieties of mushrooms, namely, G. lucidum, G. tropicum, and C. indica grown in Bangladesh for phenolic and flavonoid content and their antioxidant properties. Moreover, the phenolic composition of the extracts was analyzed by using the HPLC-DAD system. G. lucidum extract exhibited the highest antioxidant potential as evidenced by its lowest IC₅₀ value in all the tested assay models ( μg/mL,  μg/mL,  μg/mL in DPPH, H₂O_2, and NO scavenging assay, respectively) along with the highest phenolic content ( GAE g^-1 extract). G. tropicum and C. indica extracts also showed significant antioxidant properties and a good amount of phenolic content, GAE g^-1 extract, and 47.1 ± 0.26 GAE g^-1 extract, respectively. The scavenging activity increased with the increasing concentration of extracts in all cases. The total phenolic content of the ethanolic extracts of mushroom species was highly correlated with antioxidant effects with Pearson’s correlation coefficient () values ranging from 0.8883–0.9851. The α-amylase inhibitory and antibacterial activity of G. lucidum was evaluated by using 3,5-dinitrosalicylic acid and disc diffusion method, respectively. The maximum inhibitory activity recorded against α-amylase was at a concentration of 500 μg/mL. G. lucidum extract exhibited the highest antibacterial activity against Pseudomonas aeruginosa with  mm clear zone of inhibition and an MIC value of 3.5 mg/mL. The results indicate that the mushroom species tested in this study could serve as a potential source of natural antioxidants in the development of nutraceuticals and herbal drugs for the management of oxidative stress-associated diseases as well as infectious diseases.