[Validation of Method for Nitrite Determination in Foods]

In general, nitrite in food is extracted under slightly alkaline conditions, deproteinized, and analyzed by a colorimetric method using color development by diazotization. However, depending on the sample, the sample solution may become cloudy and difficult to filter by the deproteinization treatment of the analytical method. Recently, an improved analytical method that solves these problems has been reported. Therefore, a validation study was performed on the improved analytical method was performed. The concentrations of sodium nitrite added to cod roe, fish sausage, and ham, which were not labeled with sodium nitrite, were set at the upper limits of the standards for use. We set the target values of 70-120% for trueness, less than 15% for intralaboratory reproducibility, and less than intralaboratory reproducibility for repeatability. As a result, the target values were met for the three samples verified: 88-92% for trueness, 2.0-3.0% for repeatability, and 3.2-4.3% for intralaboratory reproducibility. In addition, an interlaboratory study was conducted by eight institutes on the improved analytical method for nitrite. At each institution, sodium nitrite was added to the same three samples as in the validation study, at concentrations equivalent to twice the lower limit of quantification and the upper limit of the standards for use and analyzed in triplicate. The estimated trueness from the obtained analyses ranged from 82 to 95%, the repeatability ranged from 2.3 to 5.8%, and the inter-room reproducibility ranged from 3.5 to 11%. Thus, the improved analytical method could be useful for determining nitrite in foods.

Processing Technology and Quality Change during Storage of Fish Sausages with Textured Soy Protein

The addition of textured soy protein (TSP) to surimi products extends the supply of fish protein and improves nutritional and sensory properties, which has attracted considerable research interest. In this study, a single-factor experiment and orthogonal experiment were used to determine the optimal process conditions and to assess the quality indicators of fish sausages during frozen storage. The results indicated that the optimal process conditions were as follows: the addition of 15% TSP, 8% potato starch, and 5% lard oil, resulting in a gel strength of 1894.32 g·cm. During storage of the formulation-optimized fish sausages for 180 days, the water-holding capacity, whiteness, texture properties, and gel strength of the fish sausages all decreased, whereas cooking loss, thawing loss, thiobarbituric acid reactive substances value, and total volatile base nitrogen value all increased. Consequently, TSP is beneficial to improve the gel strength and sensory score of fish sausages. The quality of fish sausages with added TSP was acceptable after storage at -18 °C, for 120 days.

Optimization of process conditions for effective ohmic heating of greater lizardfish () sausage via response surface methodology

In current research, the optimization of ohmic heating on greater lizardfish (Saurida tumbil) sausage variables was carried out using response surface methodology-central composite design (RSM-CCD). The effect of process variables including voltage gradient (15-60 V/cm), time (1-15 min), and temperature (60-90^°C) on the microbial properties, pH, peroxide value, water holding capacity (WHC), and cooking loss of the sausages was evaluated. The results showed that the characteristics of the sausages were dependent on the ohmic heating conditions and these properties can be modulated. As per the results, the voltage gradient and temperature has a significant effect on the total plate count (p < 0.05). The increase in voltage gradient was the most effective on pH (5.63-6.91). The interaction terms of all items had a significant effect (p < 0.05) on the peroxide value of the fish sausages. Higher amount of temperature and process time were resulted in the more cooking loss. Increasing the voltage gradient was more effective on WHC compared to the temperature. Finally, the process was optimized and the optimized condition was achieved by setting the voltage gradient at 30 V/cm, process time at 4 min, and temperature at 66°C. Also, it was compared with conventional heating. The results were shown that the differences between the mean values of all responses were statistically significant (p < 0.05) except for pH. Therefore, ohmic method was carried out faster, with lower temperature and obtaining the highest WHC and lowest total plate count, peroxide value, cooking loss, and optimized pH. Generally, this study suggested that the ohmic heating can be used as a rapid and homogeneous cooking method for the preparation of sausages from greater lizardfish as a commercial low-valued fish.

Stability of refrigerated traditional and liquid smoked catfish (Sciades herzbergii) sausages

Catfish (Sciades herzbergii) are widely captured in Brazilian Northeast but have low commercial value. The processing of catfish into an innovative product with longer shelf life can add value to the fish and improve sustainability. The objective of this study was to investigate the stability during 60 days of refrigerated storage smoked sausages produced by two different smoking processes (traditional smoking [TS] and liquid smoking [LS]). The smoking processes affected fat and ash contents, hardness, and CIE (Commission Internationale de L'Eclairage) color (L* and b* values). TS sausages had higher fat content and yellowness (b* value). LS sausages had higher ash content (15 days of storage) and lightness (L* value). The sausage's hardness was higher at 45 days of storage for TS and at 60 days for LS sausages. During refrigerated storage, there were decreases in crude protein (309.12-263.49 g/kg, 1-30 days, respectively), water holding capacity (89.77%-87.39%, 1-45 days, respectively), and redness (a* value) (10.35-6.09, 1-30 days, respectively), and increases in hardness (TS = 31.92-55.92 N, 1-45 days, respectively; LS = 32.88-61.18N, 160 days, respectively) and TBARS values (1.56-2.38 mg malonaldehyde/kg, 1-60 days, respectively). The microbial quality was kept within Brazilian legislation limits. Therefore, liquid smoked catfish sausage consists of a convenient innovative product, which is easier to process and control and provides a product with good physicochemical, microbial, and biochemical characteristics for up to 60 days of storage. PRACTICAL APPLICATION: Catfish, a low commercial value fish (by catch from shrimp operations), can be processed into a high value smoked sausage. Liquid smoking was easier to process, environment friendly, and easier to control compared to traditional smoking. It provided a nutritional, easy to prepare at home, and microbial safe product with a shelf life under refrigeration up to 60 days. It can be successfully used to warrant sustainability in the fish chain.

Onion Peel Powder as an Antioxidant-Rich Material for Sausages Prepared from Mechanically Separated Fish Meat

Mechanically separated fish meat (MSFM) can be used for the manufacturing of ready-to-eat products, such as sausages; however, it is highly perishable. Several plant by-products, including onion peel, which is rich in polyphenol antioxidants, can be added to food to extend shelf life. This study investigated the effects of the addition of onion peel powder (OPP) to sausage made from MSFM. Sausages were divided into four groups with different amounts of added OPP: 0% (control), 1%, 2%, and 3%. Cooked sausages were stored for 28 days at 5 °C. Samples were analyzed for thiobarbituric acid reactive substances, antioxidant activity, total polyphenol content, pH, and organoleptic properties. The addition of OPP significantly increased antioxidant activity and total polyphenol content and decreased pH, indicating acidic nature of OPP. Polyphenols from OPP effectively suppressed lipid oxidation. A 1–2% addition of OPP enhanced sensory properties. After the 28-day storage, the control samples received the lowest sensory score, due to the presence of a strong fishy odor, which was not present in samples with OPP. HPLC–MS/MS analysis revealed that quercetin is the most dominant compound in OPP. Overall, the results indicate that the addition of OPP in amounts of 1–2% can extend shelf life, without the deterioration of sensory properties.

Characteristic and shelf life of fish sausage: fortification with fish oil through emulsion and gelled emulsion incorporated with green tea extract

BACKGROUND

Silver carp (Hypophthalmichthys moltrix) fish sausages incorporated with three forms of refined cod liver oil (as a source of polyunsaturated fatty acids: fish oil, oil-in-water emulsion (E), gelled oil-in-water emulsion (G)) and lyophilized aqueous extract of green tea (Camellia sinensis; 700 and 900 mg kg^-1 ) were developed. The composition, technological properties (cooking loss, pH, texture, and color), sensory analysis, and microbial and oxidative stability of fish sausages during storage (4 °C) were evaluated.

RESULTS

Lower value of cooking loss and thiobarbituric acid value were observed by addition of fish oil in emulsions forms. The incorporation of green tea showed no significant differences in preventing oxidation in related samples. Gelled-emulsified fish oil had better textural properties, including hardness and decreased springiness of the sausages. The G and E sausages showed higher values of lightness (L^* ) than the control did. Emulsification had no significant effect on total viable count. Panelists could not distinguish between samples incorporated with fish oil whether in emulsified, gelled-emulsified, or control. Gelled-emulsified treatments were awarded higher scores by panelists for all of the sensory attributes (P < 0.05). Eicosapentaenoic acid and docosahexaenoic acid quantities significantly increased from control (0.48 mg g^-1 and 0.46 mg g^-1 sample respectively) to the enriched batches (>1.50 mg g^-1 sample). The lowest ratio of ω6 to ω3 in batches was observed for gelled-emulsified samples.

CONCLUSION

Overall, the addition of free fish oil affected the properties of the sausages. The gelled-emulsified treatment was a suitable fish oil delivery system in fish sausages, which maintained sensory properties during refrigerated storage.