A comparative study of diploid versus triploid Atlantic salmon (Salmo salar L.). The effects of rearing temperatures (5, 10 and 15°C) on raw material characteristics and storage quality

Application of soluble gas stabilization technology on ready-to-eat pre-rigor filleted Atlantic salmon (Salmo salar L.)

Abstract

The demand for high‐quality, convenient, and sustainable salmon products represents a potential for value‐added product development and novel packaging solutions. Soluble gas stabilization (SGS) technology, which applies dissolved CO₂ in the product before packaging, represents a novel approach to retain product quality and prevent microbiological deterioration during cold storage of pre‐rigor filleted salmon loins.

The present study aimed to examine the solubility of CO₂ in salmon loins as affected by rigor status. In addition, the effect of predissolved CO₂ on the overall quality of pre‐rigor vacuum‐packed Atlantic salmon (Salmo salar L.) was investigated during storage at 4°C. The CO₂ pretreatment was conducted, exposing loins to 100% CO₂ for 18 h at 4°C (the control group was kept in air at 4°C) before repackaging and storage for 15 days.

Dissolved CO₂ in the muscle (equilibrium achieved four days post packaging) was slightly higher in pre‐rigor than post‐rigor salmon loins (p_equilibrium = 0.006). Moreover, the overall spoilage (Hvalue) and microbiological stability of salmon fillets stored in SGS‐vacuum were significantly improved compared to vacuum‐packed loins (p < 0.05).

The results demonstrate that SGS technology can maintain the overall quality of pre‐rigor vacuum‐packed salmon loins without introducing the high gas‐to‐product volume ratio recognized by modified atmosphere packaging. Thus, the application of SGS technology on pre‐rigor loins can lead to higher economic gain and environmental benefits due to the reduced amount of required packaging material and reduced food waste.

Practical Application

CO₂ can be dissolved in pre‐rigor salmon loins before vacuum packaging to increase product shelf life during cold storage.

Water holding properties of Atlantic salmon

With global seafood production increasing to feed the rising population, there is a need to produce fish and fishery products of high quality and freshness. Water holding properties, including drip loss (DL) and water holding capacity (WHC), are important parameters in determining fish quality as they affect functional properties of muscles such as juiciness and texture. This review focuses on the water holding properties of Atlantic salmon and evaluates the methods used to measure them. The pre- and postmortem factors and how processing and preservation methods influence water holding properties and their correlations to other quality parameters are reviewed. In addition, the possibility of using modelling is explained. Several methods are available to measure WHC. The most prevalent method is the centrifugation method, but other non-invasive and cost-effective approaches are increasingly preferred. The advantages and disadvantages of these methods and future trends are evaluated. Due to the diversity of methods, results from previous research are relative and cannot be directly compared unless the same method is used with the same conditions.

Effects of super-chilling storage on shelf-life and quality indicators of Coregonus peled based on proteomics analysis

The advantages of super-chilling storage at -2 °C for maintaining the quality of Coregonus peled muscle were investigated using the rigor-mortis index (RM), ATP-related compounds, K-value, muscle hardness, impedance measurement, and total viable count. The results indicated that the softening of fish muscle and increase in K-value were substantially suppressed following storage at -2 °C compared to that at 0 °C. In particular, the hardness of fish muscle stored for 6 days at -2 °C was much higher than that of the samples stored for 2 days at 0 °C. The K-value increased to 81% after 6 days at 0 °C, while increased to 57% at -2 °C. The impedance changed in a biphasic manner throughout the storage period. The initial increase accompanied by the progression of RM was followed by a gradual decrease. However, this decrease was much slower at -2 °C than 0 °C. Furthermore, proteomics analysis demonstrated that the mechanism of fish freshness changes between the two storage temperatures. Differentially abundant proteins between the samples stored at two temperatures were mainly involved in the cellular component and molecular function (GO pathway) as well as collagen digestion (KEGG pathway), which might be related to muscle textural properties. Therefore, super-chilling storage is a possible method for maintaining the freshness of Coregonus peled.

Estimating freshness of ice storage rainbow trout using bioelectrical impedance analysis

This study aimed to evaluate the freshness of ice stored rainbow trout by bioelectrical impedance measurements. Rigor mortis, ATP-related components, K-value, and hardness of rainbow trout muscle during storage were monitored along with impedance. The results showed that the progress of rigor mortis was accompanied by an increase in impedance. Impedance kept decreasing even in rigor state, and during the gradual resolution of rigor mortis with impedance change upon storage of fish was biphasic (r = -0.944, p < .01). Thus, when impedance decreased close to the lowest value, K-value was only about 61.57 ± 0.52%, but still exhibited a high pertinence (r = -0.959, p < .01). A gradual decrease of the hardness of fish muscle upon storage of fish showed a close correlation (r = 0.981, p < .01) with impedance decrease. These results suggested that the impedance measurement has a great potential for predicting the freshness of the rainbow trout during ice storage.

Characterization of Chinese hamster ovary cells with disparate chromosome numbers: Reduction of the amount of mRNA relative to total protein

Chromosomes in Chinese hamster ovary (CHO) cells are labile. We have shown that high-chromosome-number CHO cells have greater potential to become robust producers of recombinant proteins. One explanation being the increase in transgene integration sites. However, high-chromosome-number cell clones produce more IgG3 following culture of single-cell clones, even under conditions that yield the same number of integrations as cells with normal chromosome numbers. Here, we characterized high-chromosome-number cells by transcriptome analysis. RNA standards were used to normalize transcriptomes of cells that had different chromosome numbers. Our results demonstrate that the mRNA ratio of β-actin and many other genes in high-chromosome-number cells to that in normal-chromosome-number cells per cell (normalized to RNA standards) was smaller than the equivalent genomic size and cell volume ratios. Many genes encoding membrane proteins are more highly expressed in high-chromosome-number cells, probably due to differences in cell size caused by the increase in chromosomes. In addition, genes related to histone modification and lipid metabolism are differentially expressed. The reduced transcript level required per protein produced in total and the different intracellular signal transductions might be key factors for antibody production.