The functional, nutritional, and antioxidative properties of hydrolyzed herring and herring byproducts (head and gonad) were evaluated. All freeze-dried herring fish protein hydrolysate (FPH) powders were light yellow and contained 77% to 87% protein. The degree of hydrolysis was 18.3%, 13%, 13%, and 10.1%, respectively, for head, whole fish, body, and gonad after 75 min digestion. All FPH powders had desirable essential amino acid profiles and mineral contents. The emulsifying capacity and stability of all FPH powders were lower than those of egg albumin and soy protein; the fat adsorption was comparable to that of egg albumin. The antioxidative activity of whole herring FPH was highest, followed by that of body, gonad, and head.

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The objective of this study was to determine important chemical characteristics of a full-strength liquid smoke, Code 10-Poly, and three refined liquid smoke products (AM-3, AM-10 and 1291) commercially available (Kerry Ingredients and Flavors, Monterey, TN). The pH of the products were significantly different (P < 0.05) and ranged from 2.3 (Code 10-Poly) to 5.7 (1291). The pH was inversely correlated with titratable acidity (R2 = 0.87), which was significantly different (P < 0.05) among products ranging from 10.3% acetic acid (Code 10-Poly) to 0.7% acetic acid (1291). Total phenol content was quantified using the Gibbs reaction; the only liquid smoke containing appreciable level of phenolic compounds was Code 10-Poly at 3.22 mg mL−1. Gas chromatography-mass spectrometry (GC-MS) analysis of liquid smoke dichloromethane extracts revealed that carbonyl-containing compounds were major constituents of all products, in which 1-hydroxy-2-butanone, 2(5H)-furanone, propanal and cyclopentenone predominated. Organic acids were detected by GC-MS in all extracts and correlated positively (R2 = 0.98) with titratable acidity. The GC-MS data showed that phenolic compounds constituted a major portion of Code 10-Poly, and were detected only in trace quantities in 1291. The refined liquid smokes had lighter color, lower acidity, and reduced level of carbonyl-containing compounds and organic acids. Our study revealed major differences in pH, titratable acidity, total phenol content, color and chemical make-up of the full-strength and refined liquid smokes. The three refined liquid smoke products studied have less flavor and color active compounds, when compared with the full-strength product. Furthermore, the three refined products studied have unique chemical characteristics and will impart specific sensorial properties to food systems. Understanding the chemical composition of liquid smokes, be these refined or full-strength products, is an important step to establish their functions and appropriate use in food systems.

The objective of this study was to investigate quality changes of salmon fillet muscle during thermal sterilization processes. Small samples (D 30 mm x H 6 mm) from the central dorsal region were heated in an oil bath at 121.1 degrees C for periods varying from 5 to 120 min. The quality variations along the longitudinal axis of salmon fillets (raw and heated) were examined. The quality properties studied included shear force, color, cook loss, and shrinkage. To minimize the influence of the heterogeneity of the salmon muscle, a multiple thin blade texture device was developed for shear force measurement and a computer vision system was used to facilitate accurate measurements of color and shrinkage. The red muscle was firmer than the white muscle in the raw but not in heated samples. Muscle from the central dorsal region had a lower cook loss and less shrinkage than samples from either the anterior or posterior region following heating. The greatest change in quality occurred within the 1st 10 min of heating at 121.1 degrees C. Shear force measurements following heating indicated 2 peaks, one corresponding to 5 min and the second for 60 min processing at 121.1 degrees C. Possible mechanisms were discussed.

Five commercial liquid smokes were tested in vitro and the most inhibitory to Listeria monocytogenes ATCC 19115 and L. innocua ATCC 33090 was Charsol Supreme. Chum salmon samples (100‐g each) were brined, dipped for 15 s at varying concentrations of liquid smoke, inoculated with L. innocua, cold‐processed and analyzed. Liquid smoke concentrations of 60–100% reduced L. innocua by 3‐log10/g in the final product. Dwell times of 15 s to 5 min using 60% liquid smoke gradually decreased Listeria survival with an optimum 5‐min dip. Isoeugenol was antilisterial in vitro but lacked synergism with liquid smoke in cold‐smoked salmon. An immunoassay kit detected low inoculum levels (< 100 CFU/g) of L. innocua in one of three samples that were treated with liquid smoke for two and four minutes. Charsol Supreme was antilisterial but could not be relied on to totally eliminate Listeria in cold‐smoked salmon. Panelists found the 0 to 2‐min dipped sockeye salmon slightly desirable with no significant (p < 0.05) differences. The 5‐min treatment was significantly (p < 0.05) darker, scored lower in desirability and flavor and contained 93 ppm of phenolic compounds.