Effects of aqueous antioxidants extracts from ginger, garlic and onion on 2-thiobarbituric Acid Reactive Substances and total volatile basic nitrogen content in chevon (goat meat) and pork during frozen storage

The study investigated the effect of 10% aqueous extracts of ginger ( Zingiber officinale L.), garlic ( Allium sativum L.) and onion ( Allium cepa L.) on the quality of frozen chevon and pork as reflected by changes in values of 2-thiobartituric Acid Reactive Substances (2-TBARS), pH and total volatile basic nitrogen (TVB-N) over a 14 day storage under frozen conditions. Fresh samples each weighing 2 kg from chevon and pork were bought from the local slaughter houses in two locations 24hrs after slaughtering while ginger roots, garlic and onion bulbs were purchased from Mitundu local market in Lilongwe district, Malawi. The pH, total 2-TBARS and TVB-N of the thigh chevon and pork were measured from frozen storage at -20 o C after 14 days. The 10% aqueous extracts resulted in low pH values of 5.63, 5.79 and 5.67 at 14 d for chevon mixed with ginger, garlic and onion respectively. However, treated pork had higher pH content compared to treated chevon at 14 d. At day14 of frozen storage, the 2-TBARS expressed as mg MDA/kg meat, for chevon mixed with ginger, garlic and onion aqueous extracts were 2.62±0.01, 0 and 4.71±0.03 which was lower compared to the value of 5.93±0.01 for raw chevon. The TBARS values of chevon and pork mixed with ginger, garlic and onion and control chevon decreased from day 0 to 7 which eventually increased on 14 d. On 14 d, pork mixed with garlic extracts had lower TBARS value of 2.13±0.01 compared to 3.50±0.20, 2.26±0.01 and 3.92±0.01 for pork mixed with extracts of onion, ginger and control pork sample respectively. TVB-N, in mg/100g, was highest in control raw chevon and pork registering 95.70±0.32 and 84.00±0.40 at 14 d. Low values of TVB-N of 7.24±0.23, 12.37±0.23 and 16.61v±0.50 were registered in chevon mixed with aqueous extracts of ginger, garlic and onion compared to the values of 14.23±0.62, 22.87±0.47 and 18.86±0.14 for pork mixed with aqueous extracts of ginger, garlic and onion. The results of the study have revealed that natural aqueous antioxidant extracts of ginger, garlic and onion have antioxidative effect on lipid peroxidation in frozen stored fresh chevon and pork signifying that the use of these extracts can maintain quality.

Chemical and bacteriological risks of shrimp and clams (Gandofly) from Suez Gulf

Shellfish including shrimp and clams are consumed allover the world for their nutritional value, however, handling in seafood markets may challenge their safety and quality. Shellfish products in the fish markets in Suez Governorate were evaluated throughchemical analysis of total volatile basic nitrogen value, thiobarbituric acid, histamine content, and some heavy metals residues. As well as, microbiological estimation of the total aerobic counts, Enterobacteriaceae counts, Escherichia coli counts, and Staphylococcus aureus counts, in addition of Salmonella detection. Results declared that more than half of the examined samples of shrimp and clams (gandofly) were fit for human consumption based on the permissible limits of the Egyptian standard. Otherwise, some gandofly samples contain high levels of total volatile basic nitrogen (TVB-N), thiobarbituric acid reactive substance (TBA), and may cause scombroid food poisoning with elevated histamine level. The levels of cadmium, lead, and zinc in shellfish samples under study was different with the sequence: Zn>Pb>Cd. Bacteria including E. coli and Staphylococcus aureus were identified. The analysed samples in this study were judged as medium/good quality market samples as more than half of the examined samples were within the Egyptian standard and may indicate that trading of shellfish at Suez markets went under abuse storage temperature.

Effect of applying crust-freezing after skin-packaging on the natural microflora of Atlantic salmon (Salmo salar) during storage at low temperatures

The aim of the present study was to evaluate the effect of crust-freezing (CF) on fresh salmon fillets in skin-packaging during storage at −2.0°C. After CF, all treated samples and untreated controls were stored in a refrigerated cabinet for 20 d. Sampling was carried out at days 0, 2, 6, 8, 10, 14 and 20 in order to analyse total volatile basic nitrogen (TVB-N) and levels of mesophilic and psychrophilic viable counts (MVC and PVC). Enterobacteriaceae (ENT), lactic acid bacteria (LAB), H2S-producing bacteria (SPB) and Pseudomonas spp. (PSE). No significant differences in TVB-N were found between samples except for those taken on day 20 where TVB-N levels of CF samples were lower than controls. Our results suggest that ENT might be the limiting microbial group to determine the end of shelf-life. Thus, if this group is used as an indicator of acceptability, the shelf-life of salmon can be extended from 8 to 20 d when skin-packed and then treated with CF.

Effects of Vacuum and Modified Atmosphere Packaging on the Quality and Shelf-Life of Gray Triggerfish (Balistes capriscus) Fillets

Seafood products are perceived as healthy foods. However, several species of seafood are still not fully utilized for different reasons or can be valued outside the original locale, if issues with the short shelf-life and/or the preparation/presentation form are overcome, e.g., gray triggerfish, Balistes capriscus. Consumed mostly fresh, its flesh is of excellent quality. We studied the effect of different types of packaging (in air (AIR), vacuum (VP), and modified atmosphere (MAP)) on physicochemical (color and texture, pH, and total volatile basic nitrogen), microbiological (total viable count, psychrotrophic, sulphide-reducing bacteria, and acid-lactic bacteria), and sensory qualities, and shelf-life of gray triggerfish fillets stored at refrigeration temperature for 15 days. The samples were analyzed on days 0 (fresh fish), 5, 10 (8 and 12 for sensory analysis), and 15 after filleting and packaging. During the trial, fillets became lighter (increased L*) and yellower (b* >> 0) with time of storage. Distinct patterns were observed for pH among treatments. Unexpectedly, the increasing trend observed in the texturometer-derived hardness of VP and MAP fillets, contrasted with the sensory assessment, wherein panelists perceived a clear softening of fillets. VP delayed and MAP inhibited the increase in TVB-N contents of fillets compared to fillets packed in AIR. Total viable count and psychrothropic bacteria of fillets in AIR exceeded the conventional limit of 7 log(CFU/g) on day 10, while in fillets packed in VP and MAP, their abundance remained below that limit during the trial. The organoleptic attributes of fillets perceived by a sensory panel changed significantly in all treatments during the storage trial. Willingness to consume the fillets decreased constantly in AIR and MAP, but not in VP fillets. Considering primarily sensory, but also biochemical and microbiological parameters, namely panelists’ rejection, total volatile basic nitrogen content, and total viable count and psychrotrophic bacteria abundance, the shelf-life of fillets packed in air was eight days. Vacuum and modified atmosphere packaging extended the shelf-life to 15 and 12 days, and thus can add value to this product. Future research regarding the VP and MAP of gray triggerfish fillets could involve the optimization of mixtures of gases use and/or the application of combined processes.