Superchilling in combination with modified atmosphere packaging resulted in long shelf-life and limited microbial growth in Atlantic cod (Gadus morhua L.) from capture-based-aquaculture in Greenland.

Sensory, chemical and microbial changes for Atlantic cod (Gadus morhua L.) filets from capture-based-aquaculture in Greenland were studied. The objective was to determine shelf-life and indices of spoilage for iced or superchilled fillets when stored in air, or modified atmosphere packed (MAP; 40% CO2 and 60% N2). MAP iced storage extended the sensory shelf-life from 15 days to 21 days compared to storage in air. With superchilling at -1.7 °C sensory shelf-life was above 32 days, and no formation of total volatile nitrogen (TVN) was observed irrespective of storage in air or MAP. pH of ≥7.0, TVN (≥35 mg-N/100 g) and trimethylamine (≥20 mg-N TMA/100 g) were promising indices of spoilage. Aerobic viable counts were less valuable indices of spoilage as the dominating microbiota of cod in air (Pseudomonas spp., Photobacterium spp., Shewanella spp., Acinetobacter spp.) changed to Photobacterium spp. in MAP cod. Spoilage activity determined as the yield factor for TVN formation was 6-200 folds higher for Photobacterium spp. compared to Shewanella spp. and Pseudomonas spp. Photobacterium carnosum was responsible for TVN formation in iced cod irrespective of storage in air or MAP, and it was identified at the specific spoilage organism that limited iced product shelf-life.

Protein phosphorylation profile of Atlantic cod (Gadus morhua) in response to pre-slaughter pumping stress and postmortem time.

This study aimed to evaluate the effect of pumping stress (pumping and pumping-resting) and postmortem time (before and after rigor mortis) on phosphorylation profiles of myofibrillar protein (MP) and sarcoplasmic protein (SP) of Atlantic cod (Gadus morhua) fillets. The result showed that MP had higher global phosphorylation levels than SP regardless of stress condition and postmortem time. The pumping process resulted in significant changes in phosphorylation of structural proteins including myosin heavy and light chains. Pumping also affected the phosphorylation status of heat shock proteins and metabolic enzymes involved in the glycolytic pathways, indicating the possible role of phosphorylation in regulating energy hemostasis of fish under stressful conditions. The pumping-induced phosphorylation changes mainly occurred before rigor mortis, and postmortem time affected the phosphorylation status to a less extent. This work contributes to a deeper understanding on protein phosphorylation affected by pre-slaughter stress and postmortem time of fish.

Quality and safety aspects in fermentation of winged kelp (Alaria esculenta) and sugar kelp (Saccharina latissima) by the natural microbiota with or without addition of a Lactiplantibacillus plantarum starter culture.

Nourishment of the growing human population requires new and alternative food sources, preferable produced without occupying new land areas. Cultivation of seaweed presents an opportunity, however, a major obstacle is sustainable preservation. Fermentation has been used for centuries to preserve vegetables, e.g., to produce kimchi based on cabbage. This study investigated changes in the microbiota, characteristics (pH, organic acids and water soluble carbohydrates) and food safety of raw shredded Alaria esculenta and Saccharina latissima during fermentation by the natural microbiota with or without addition of a Lactiplantibacillus plantarum starter culture. The Lb. plantarum fermented products retained a high Shannon diversity index, indicating a partially unsuccessful fermentation. Lb. plantarum performed better in A. esculenta causing pH to drop to below 4.6, a critical limit for control of growth of Clostridium botulinum, within 2 days compared to 7 days for S. latissima. Natural fermentation by the endogenous microbiota resulted in unsafe products with high final pH values (4.8-5.2), presence of unwanted organic acids, such as butyric acid, and in the case of A. esculenta sustenance of inoculated Listeria monocytogenes. Fermentation of A. esculenta and S. latissima by Lb. plantarum is a promising preservation method. However, future work is needed to optimise the process, by investigation of the use of different starter cultures, seaweed pre-treatments (blanching, freezing, etc.) and adjuvants (i.e., addition of sugars, minerals and similar) to promote growth of the starter culture and ensure the fermented products are safe to eat.