Asian Food Science Journal

Effect of Some Preservatives on the Microbial Quality of Cold-smoked Catfish at Refrigerated Temperature

Ubadire-Agua, C. — 2023-09-12

Aim: This study investigated the preservative effect of potassium sorbate, ginger, garlic, and a blend of, ginger and garlic on the microbiological quality and shelf stability of cold smoked Catfish (Clarius gariepinus) at refrigerated storage.

Methodology: One hundred (100) of the freshly harvested catfish obtained from the MOUAU Fish Farm were processed and divided into five lots of 20 each. Four marinating baths containing 0.5% potassium sorbate, 3% ginger, 3% garlic, and a blend of 1.5% ginger and 1.5% garlic respectively were prepared. Each catfish lot except the fifth lot (which served as a control) was marinated for 2 h and cold smoked for 8 h. The samples were then stored for fourteen days at refrigeration temperature (4 ± 2 °C during which analyses were carried out. The Total viable count, Total fungal count, and bacterial counts (Escherichia coli, Salmonella, Staphylococcus sp, and Listeria sp) of the catfish samples before, during, and after storage were analyzed.

Results: The total viable count (TVC) was reduced from 8.7x10⁵to 1.2x10⁵ CFU/g, 1.13 x10⁶to 2.4x10⁵ CFU/g, 1.09 x 10⁶to 2.00 x10⁵ CFU/g, 9.60 x10⁵ to 1.50 x10⁵ CFU/g, and 1.19x10⁶ to 3.00x10⁵ CFU/g for 3% ginger, 3% garlic, 1.5% ginger +1.5% garlic, 0.5% potassium sorbate, and the control at refrigeration storage respectively. All the treatments were effective against E. coli, Listeria monocytogen, and Salmonella count. Similarly, the 3% of ginger treatment recorded counts of 1x10⁵ CFU/g for Staphylococcus counts, during refrigeration storage. Furthermore, the total fungal count decreased for all the treatments.

Conclusion: The study found that cold smoked catfish treated with 0.5% potassium sorbate, 3% ginger, 3% garlic and a blend of 1.5% ginger and 1.5% garlic can be stored for 14 days at refrigeration storage provided the storage condition is maintained.

Effect of Ginger and Garlic Marinates on Growth of Microbial Contaminants in Cold-Smoked Catfish (Clarius gariepinus) Stored at Room Condition

Ubadire-Agua C. — 2023-09-14

Aim: In this study, the preservative effect of potassium sorbate, ginger, garlic and a combination of ginger – garlic on the microbiological quality and shelf stability of cold-smoked Catfish (Clarius gariepinus) were investigated.

Methodology: A total of 100 fresh catfish from Michael Okpara University of Agriculture, Umudike (MOUAU) Nigeria Fish Farm was used for the analysis. The fish were processed and divided into five lots of twenty each. This was followed by marinating in baths containing 0.5% potassium sorbate, 3% ginger, 3% garlic, and a mix of 1.5% ginger and 1.5% garlic each and a control for 2h. Afterwards, the treated fish was cold-smoked for 8 h and then stored at room temperature (28 ± 2°C). Fish samples were collected at 2-day intervals to determine total viable count, total fungal count, and bacterial counts (Escherichia coli, Salmonella, Staphylococcus sp, and Listeria sp.).

Results: Findings of this study revealed that potassium sorbate, ginger, garlic, and ginger-garlic blends enhanced the microbiological safety of cold–smoked Catfish (Clarius gariepius). The result showed that although counts of some microbial contaminants increased in the cold-smoked fish, however, it varied (p˂0.05) with the treatment during storage. Comparatively, 1.5% ginger - 1.5% garlic marinate was the most effective and performed considerably higher (p˂0.05) than 0.5% potassium sorbate in the reduction of the microbial contaminants. In this study, the lowest total viable counts were observed in the 3% ginger–treated cold smoked fish (8.7x10⁵cfu/g) while the untreated sample was the most contaminated (1.19 x 10⁶ cfu/g) at pre-storage. A significant increase in the total viable count was observed in all the samples during storage however, 3% garlic recorded the least (1.13 x 10⁶ to 2.84 x10⁶to 3.48x10⁶cfu/g) and the highest in the untreated sample (1.19 x 10⁶ to 3.38 x 10⁶ to 3.66x 10⁶ cfu/g). Overall, 1.5%ginger+1.5%garlic blend was most effective on E. coli while 0.5% potassium sorbate was on Salmonella at ambient storage. Listeria monocytogenes was most susceptible to all the treatment, the growth of fungi steadily increased in the treated cold smoked fish during ambient storage.

Conclusion: The study found that 3% ginger, 3% garlic, 1.5% ginger - 1.5% garlic mixture inhibits significantly the growth of microbial contaminants relatively with 0.5% potassium sorbate in cold-smoked fish during ambient storage.

Improving the Antioxidant Activity of a Carbonated Lemon Soft Drink

Mohamed Yehia Sayed Ahmed — 2023-09-25

The carbonated functional soft drinks are a new concept that provides health benefits for the consumers. The aim of this study was to improve the antioxidant activity of a carbonated lemon soft drink, while preserving its characteristic flavour, by blending the lemon oil (L) with oregano (Or) essential oil. The effect of different thickeners, usually used in formulation of the soft drinks, on release of the volatile compounds from simple model solutions was evaluated, separately. Blending lemon oil with oregano essential oil (1.5 µL Or /100 µL) improved the odour acceptability and increased the DPPH scavenging ability of lemon oil by 40%. Studying the effect of different thickeners indicated that the xanthan, Arabic gum and pectin at levels 0.05, 6.0 and 0.01 g/100 mL water, respectively, showed the highest release of limonene and citral, the most contributors to lemon aroma, from the simple model solutions. This finding was mainly correlated to the interaction between the thickeners. In view of this result a lemon soft drink was formulated. Carbonation of the soft drink improved the sensory characteristics, decreased the pH value, increased the acidity and showed insignificant changes (P > 0.05) in total soluble solids and total sugars.

Development and Performance Evaluation of Hybrid-Solar Dryer for Cassava Grate

Patricia Omonegho Adejumo — 2023-09-26

A solar hybrid dryer for cassava grate was fabricated and evaluated for performance. The major components include chimney, drying chamber, solar collector, blower housing (heater and fan) unit, solar panel, aluminum frame, rollers and 12 V direct current battery. Evaluation of the hybrid dryer was carried out to investigate the effect of drying temperature and variety of cassava (TMS96/1414, TMS92/0326 and TMS01/1368) on moisture loss, drying rate and drying efficiency. The dryer recorded maximum temperature of 55ᵒC and 45ᵒC in the drying chamber for hybrid and solar drying respectively which are higher than the 26ᵒC recorded for ambient. In all the experiments performed it took 7 hours for the moisture content of sample using hybrid solar drying to be reduced from average of 65% to about 10.19%. For solar drying it took 13 hours to attain moisture content of 11% while open sun drying took 35 hours to reduce the moisture content to 13 %. The result showed that TMS96/0326 had the highest moisture loss (6.20 kg/kg, 6.09 kg/kg and 5.65kg/kg) drying rate (0.899 kg/hr, 0.870 kg/hr and 0.807 kg/hr) for open sun, solar and hybrid drying respectively. This confirmed that variety and temperature had effect on the drying performance. The drying efficiency for hybrid drying was 78.71 %, 79.71 % and 73.42 % while solar drying had 47.76 %, 48.38 % and 44.53 % for TMS96/1414, TMS92/0326 and TMS01/1368 respectively; an indication that temperature, airflow rate and variety of cassava grate had significant effect on evaluated parameters hence the hybrid solar dryer is efficient for achieving dry cassava grate.