Clostridium botulinum Toxin Production in Relation to Spoilage of Atlantic Salmon (Salmo salar) Packaged in Films of Varying Oxygen Permeabilities and with Different Atmospheres

Abstract

Shelf life of fish packaged under modified atmosphere (MA) is extended, but within the United States, commercial application of MA with impermeable packaging films is restricted due to concerns that botulinum toxin production would precede spoilage when contaminated fish are held at abusive storage temperatures. Use of semipermeable packaging films has been advocated; however, previous studies are inconclusive in determining the oxygen transmission rate (OTR) of a film that is needed to achieve an acceptable margin of safety (i.e., toxin production occurs only after spoilage). This study was conducted to determine the influence of OTR (target OTRs of 3 to 15,000) on the development of spoilage volatiles and toxin in salmon inoculated with type E Clostridium botulinum and subjected to air, vacuum, or 75:25 CO2:N2 MA and storage temperatures of 4, 8, 12, or 16°C. The most dominant headspace volatile peak that was produced during spoilage of samples at 4, 8 or 12°C was a peak, having a Kovats retention index (KI) of 753, and at which external standards of 2- or 3-methyl 1-butanol also eluted. Under anaerobic conditions, both the aerobic microbial populations and the size of the KI 753 spoilage peak were less in inoculated samples compared with uninoculated samples. C. botulinum-inoculated samples that were stored at 12 or 16°C under conditions favorable for anaerobic growth were also characterized by a KI 688 peak. Using a previously developed model that related the percentage of elderly consumers who would prepare a sample having the KI 753 spoilage peak of a specific size, it was determined that for salmon packaged with 3 or 3,000 OTR films under any atmosphere and stored at 12 or 16°C, 2 to 61% of the consumers could potentially prepare toxin-contaminated samples. Hence, when abusive storage conditions are suspected, the fish should not be consumed.

Volatilome Analysis and Evolution in the Headspace of Packed Refrigerated Fish

“…The headspace atmosphere composition, namely O 2 and CO 2 percentages, is a rather simple analysis implemented to study the fresh fish spoilage when packed under air (AP), vacuum (VP) or modified atmosphere (MAP) [23]. MAP of fish generally relies upon an increased CO 2 concentration, from 20 to 80% [4], this gas being reported as extending the lag and generation times of aerobic bacteria, yeasts, and molds, thereby reducing their metabolic activity and growth [24]. Indeed, it is well-known that VP and MAP extend the shelf life of refrigerated fish (generally stored between 0 • C and 4 • C) from 2 days to 2 weeks [25,26] or even longer if stored at super-chilling temperatures (−2 • C) [10].…”

“…Nevertheless, Gokoglu [100], in his review dedicated to seafood packaging, reported the upcoming use of ternary MAP (i.e., CO 2 -O 2 MAP with low O 2 levels) to prevent both the reduction of TMAO to TMA and anaerobic bacteria growth. Erickson et al [24] also discussed the use of O 2 semi-permeable packaging to ensure a progressive O 2 ingress in the headspace of packaging. If packed fish is exposed to temperature abuse, O 2 presence could prevent the growth and toxin production by C. botulinum, monitored before spoilage and possibly detected by the analysis of headspace volatile compounds (increase in a peak on GC-chromatogram coincided with the formation of toxin).…”

Effect of Physicochemical Characteristics and Storage Atmosphere on Microbiological Stability and Shelf-Life of Minimally Processed European Sea Bass (Dicentrarchus labrax) Fillets

“…It has to be pointed out that in reduced oxygen packaging, major safety issues related to anoxic conditions must be considered, since in such products there is the risk of Clostridium botulinum type E [ 17 ]. To tackle this, there are some options regarding the control of the product’s intrinsic properties such as a w , salt content and pH and/or the use of a high oxygen permeability package [ 18 , 19 ].…”

Oxygen transfer in co‐extruded multilayer active films for food packaging

“…This could lead to adverse quality deterioration such as loss of ascorbic acid, browning, increased respiration in fruits and vegetables, oxidative rancidity of unsaturated fats, darkening of fresh meat pigments, fostering the growth of mold and aerobic spoilage microorganisms to count only a few. Conversely, inadequate oxygen concentration around the food product could promote the growth of anaerobic pathogens microorganisms, such as C. botulinum …”