Combined Hurdle Effects of Process Parameters on Biochemical, Microbiological and Sensory Attributes of Trout Fillets

Abstract

The combined effect of brining time, citric acid, oregano oil and pasteurization temperature on the microbiological stability, pH, lipid oxidation (thiobarbituric acid reactive substance [TBARS]), total volatile basic nitrogen (TVBN) and sensory characteristics of trout fillets was evaluated. Sixteen treatment combinations were produced, packaged under modified atmosphere conditions and were studied for a period of 150 days. The total viable counts, phychrophiles, sulfite‐reducing clostridia and lactic acid bacteria populations were present in very low numbers throughout the storage period. The addition of citric acid resulted in lower pH and TBARS values. Oregano oil had a strong antioxidant effect. Pasteurization temperatures of 95C resulted in higher TVBN numbers at the end of the storage period, compared with pasteurization temperatures of 85C. Brining times of 4 h improved the flavor of the trout fillets compared with 1‐h brining, whereas oregano oil improved the flavor only for the fillets brined for 1 h. Practical Applications This paper describes an application of combined hurdles (citric acid, oregano oil, brining and pasteurization) in order to produce ready‐to‐eat trout fillets, otherwise sensitive to microbial spoilage and lipid oxidation, with improved chemical and microbiological stability during storage. Also, it intends to highlight interactions among the combined hurdles as concern product quality. Additionally, although high pasteurization (95C) had a high bacteriocidal impact on the product, it deteriorated texture and led to increased total volatile basic nitrogen numbers. Overall, 4‐h brining combined with 0.1% citric acid, a mild heating process (85C) and a lower than 0.5% addition of oregano oil is considered the best combination for high sensorial characteristics and keeping quality. An interesting finding was the absence of detectable microflora in samples judged as unacceptable, which lead to the conclusion that enzymatic spoilage took place due to endogenous enzymes or microbial enzymes produced prior to pasteurization and processing, which is worth further investigating.

Quality changes and shelf‐life extension of ready‐to‐eat fish patties by adding encapsulated citric acid

“…Nevertheless, these differences can be considered of minimal interest taking into consideration the amounts of TVB‐N in freshly caught fish, which typically range between 100 and 200 mg N kg −1 . Similar to our findings, citric acid showed no effect on TVB‐N concentrations in trout fillets submitted to a brining process in which citric acid (1 g kg −1 ) or oregano oil (5 g kg −1 ) were added and subsequently packaged under a modified atmosphere and pasteurized …”

“…reported that dipping of the fish in lemon juice before cooking vacuum packaged fish fillets had no effect on TBARS values after 42 days of refrigerated storage. Conversely, the addition of citric acid in soaking solutions/brines, icing mediums and chitosan coatings improved the oxidative stability of fish fillets …”

Development of a convenience and safety chilled sous vide fish dish: Diversification of aquacultural products

“…(2008) found pH values in fried, baked and microwave-cooked seabass at day 0 ranging from 6.69 to 6.73. However, Giavasis et al. (2012) found lower pH values in sous vide trout fillets with citric acid added.…”

“…(2004) obtained similar TVC counts for sous vide cooked rainbow trout after 14 days of storage at 2 ℃ with a similar heat treatment. Also, Giavasis et al. (2012) found TVC to be below the detection level for 150 days in sous vide trout cooked with sunflower oil, acid citric and oregano oil.…”

Modeling the Survival of S almonella on Slice Cooked Ham as a Function of Apple Skin Polyphenols, Acetic Acid, Oregano Essential Oil and Carvacrol

“…On the contrary, the antimicrobial effect and interaction of polyphenols and carvacrol were found to be more significant with the addition of acid which reduced pH (Giavasis et al . ). In the present study, polyphenols alone exerted a limited antimicrobial effect, while its combination with acid or carvacrol resulted in a higher antimicrobial activity.…”