Effects of brine concentration on lipid oxidation and fatty acids profile of hot smoked tuna ( Thunnus albacares ) stored at refrigerated temperature

Impact of brining and drying processes on the nutritive value of tambaqui fish (Colossoma macropomum)

Preservation of fish as diet ingredient is challenging in many tropical regions due to poor socioeconomic conditions and lack of freezing facilities. So, alternative preservation techniques could be viable to address the issue. The present study evaluated the effect of brine salting (15% w/v) prior to drying at different temperatures on the nutrient profiles of tambaqui fish (Colossoma macropomum). Whole fish samples (n = 48; 792 ± 16 g; 8 months old) were grouped into two as brine-salted and non-salted, and treated at seven different drying temperatures of 30, 35, 40, 45, 50, 55 and 60°C for a period of 23 h each. To evaluate the impact of Maillard reaction, reactive lysine was also quantified. Drying temperature had no effect on the evaluated macro- and micro-nutrients of tambaqui fish (P > 0.05) while brining reduced the overall protein concentration by 6% (58.8 to 55.4 g/100 g DM; P = 0.004). Brining significantly reduced many amino acids: taurine by 56% (7.1 to 3.1 g/kg; P < 0.001), methionine 17% (14.7 to 12.1 g/kg; P < 0.001), cysteine 11% (5.1 to 4.4 g/kg, P = 0.016), and reactive lysine 11% (52.0 to 46.4 g/kg; P = 0.004). However, alanine, arginine, and serine were not affected by brining (P > 0.05). Brining also reduced the concentrations of Se by 14% (149 to 128 μg/kg DM; P = 0.020), iodine 38% (604 to 373 μg/kg DM; P = 0.020), K 42% (9.71 to 5.61 g/kg DM; P < 0.001) and Mg 18% (1.32 to 1.10 g/kg DM; P = < 0.001) versus an anticipated vast increase in Na by 744% (2.70 to 22.90 g/kg DM; P < 0.001) and ash 28% (12.4 to 16.0 g/100g DM; P < 0.001) concentration. Neither brining nor drying temperature induced changes in % lysine reactivity and fat content of tambaqui fish (P > 0.05). Agreeably, results of multivariate analysis showed a negative association between brining, Na, and ash on one side of the component and most other nutrients on the other component. In conclusion, drying without brining may better preserve the nutritive value of tambaqui fish. However, as a practical remark to the industry sector, it is recommended that the final product may further evaluated for any pathogen of economic or public health importance.

Effects of abdominal emptying and immersion in salt in different concentrations on fatty acids profile and spoilage indices of fish Kotr (Sphyraena jello) during freezing

Many studies showed that the nutritional value and the fish spoilage changed during handle and processing. In this research, 20 pieces of the Kotr fish were purchased from Behbahan market. After washing the fish, some as whole fish were frozen (sample A) and some were descaled and emptied and without salt frozen (sample B) and some were immersed in saltwater with 4% concentrations (sample C), 8% (sample D) and 12% (sample E) which then frozen. After 30 days of freezing, samples were transferred to the laboratory to measure fatty acids profile, spoilage indices, proximate composition, and microbial load. The results showed that the percentage of saturated fatty acids in whole fish was significantly lower than the other treatments. However, the percentage of omega-3, omega-6, and MUFA and PUFA fatty acids in different samples did not show a significant difference, but the ratio between DHA/EPA fatty acids changed significantly. Spoilage indexes in Sphyraena jello fillet had a significant difference in process methods. The amount of the indexes decreased with the addition of salt. The addition of salt and the abdominal emptying of S. jello resulted in a change in the fat content of the fish fillet, but did not a significant effect on protein, moisture, and ash content of fish fillet. The number of sycrophile bacteria in treatment A was 158 × 103 Cfu/g, which was higher than the other treatments. The lowest level was observed in salted 12% sample. It can be concluded that abdominal emptying and immersion of the Kotr fish in saltwater can lead to preserve the nutritional value and decrease the spoilage indices and increase the shelf life of the product.

Cold smoking of Lebranche mullet (Mugil liza): Physicochemical, sensory, and microbiological evaluation

The suitability of Mugil liza for cold smoking was evaluated and the effect of four different salting treatments on physicochemical, microbiological, and sensory characteristics was assessed. The addition of sucrose (3%) and acetic acid (0.5%) to the brine lead to fillet dehydration with lower NaCl penetration, combined with higher reduction of pH. Brining at refrigerated temperature (5 ± 1 ℃) instead of room temperature (16 ± 2 ℃) was more effective in preventing microbial growth. Loads of bacterial groups assessed in all smoked samples were below 100 CFU/g and the a_w, moisture, NaCl, and pH values achieved were within the typical stability range of smoked fish products. The obtained products were characterized by the smoked aroma and salty taste, differing in 7 of the 21 evaluated descriptors. The use of acetic acid in brine formulation showed an effect over color and texture descriptors. The affective test indicated the overall acceptability of products, being preferred the samples treated in the lowest NaCl concentration (5%).

Physicochemical, nutritional, and quality parameters of salted semidried mullet (Chelon haematocheilus) prepared with different processing methods

The mullet (Chelon haematocheilus) is a cosmopolitan coastal species. It is often consumed as a sliced raw fish in Korea and as a dried and salted fish roe in several countries, including the southeastern United States and Japan. In this study, to optimize traditional processing of salted semidried mullet (SSDM) for the development of high-quality products, nine different types of traditional process were applied, and quality changes including physicochemical, nutritional, and sanitary properties were observed. The approximate composition of SSDM was as follows: moisture, 66.1% to 71.8%; ash, 1.65% to 3.75%; crude protein, 16.12% to 18.09%; and crude lipid, 1.11% to 2.07%. The salinity, water activity (Aw), color parameters, peroxide value (POV), acid value (AV), thiobarbituric acid (TBA), and the total volatile basic nitrogen (TVB-N) contents in fresh mullet (FM) and different SSDM groups were affected by different processing techniques including salt concentration and drying methods. In particular, the salinity was significantly increased, whereas the Aw was significantly decreased in all SSDM groups compared to those of FM group. In both FM and SSDM groups, the AV, POV, and TBA values gradually increased with prolonged storage and crude fat content; however, they were not affected by salinity. The amino and fatty acid content also varied depending on the processing method; however, the composition and protein patterns were similar among the groups. The total aerobic bacterial numbers of all SSDM groups were also influenced by different processing methods. The microbial numbers in the mullet after salted semidried treatment were markedly lower than in the FM group during refrigerated storage for 14 days. Therefore, salted semidried treatment for mullet show extended shelf life and improved microbiological safety and biochemical parameters during refrigerated storage.

Influences of pulsed light-UV treatment on the storage period of dry-cured meat and shelf life prediction by ASLT method

In order to prolong the shelf life of Chinese traditional dry-cured meat products, a pulsed ultraviolet light (PL-UV) irradiation method was adopted to treat meat products according to the following parameters: pulse energy of 8 J, 300 pulses, and an effective exposure distance of 10 cm; the UV light irradiation power of 6 W, an effective exposure distance of 11 cm, and an exposure period of 5 min. After a pulsed ultraviolet irradiation, total bacterial count in dry-cured meat decreased from 6.89 to 4.53 lg (CFU/g). The number of Micrococcus and Staphylococcus in samples decreased from 6.49 to 4.10 lg (CFU/g) and the number of molds and yeasts decreased from 5.45 to 4.28 lg (CFU/g). The number of Lactic acid bacteria increased from 3.97 to 4.55 lg (CFU/g) and Escherichia coli was not detected. Total colonies, target bacteria, peroxide value, thiobarbituric acid-reactive substances, water activity, T ₂ relaxation time, pH, color difference, total volatile basic nitrogen, and the sensory evaluations of dry-cured meat products after PL-UV treatments were determined in a 30-d storage experiment. The shelf life of dry-cured meat treated with PL-UV irradiation at 20 °C was predicted to reach to 294 d by applying of shelf life testing method accelerated. The quality and safety of dry-cured meat treated with PL-UV irradiation was better than that of untreated samples.