Antimicrobial Edible Films and Coatings for Meat and Meat Products Preservation
Table 3
Use of antimicrobial films and coatings in fish and seafood.
Product
Coating material
Antimicrobial compound
Target microorganism
Inoculation technique
Conditions
Results
Ref.
Atlantic cod (Gadus morhua) and herring (Clupea harengus)
Chitosan coatings
Chitosan (CH) with different molecular weights and viscosities (14, 57 or 360 mPa s)
Psychrotrophic microorganisms (PT) and total plate count (TPC)
No inoculation
12 d, 4°C Samples immersed in CH solution (5°C) 30 s and after 2 min a second immersion for 30 s. Then they were dried at 40°C for 2 h in a forced air oven and stored
Herring fillets treated with 57 and 360 cP CH showed lower PT population than 14 cP CH-treated fillets after 6 d. CH treatments reduced to 103 and 102 TPC of herring and cod samples, respectively, after 12 d
L. monocytogenes (V7 serotype 4b, LCDC 81-861 serotype 4b, Scott A serotype 4b, 101M and 108M) (102–104 CFU/g).
Spotted directly onto the salmon (I + C) or on top of applied coating (C + I) and spread with a hockey stick
4°C and 10°C, 35 d. I + C samples were inoculated and then dried for 0.5 h and coated. C + I samples dried for 1 h and then inoculated
Samples coated by LPO-WPI showed <1.0 log CFU/g of L. monocytogenes at 4°C for 35 d (both treatments). L. monocytogenes was completely inhibited in C + I samples stored during 35 d at 10°C
Oregano extract (OE) (Origanum vulgare 1.5%, v/v) or rosemary (RM) (Rosmarinus officinalis, 20% w/v) or Chitosan (CH) (1.5% w/v), high pressure (300 MPa/20°C/15 min) (HP).
Total viable count (TVC), H2S-reducing organisms, luminescent bacteria, and Enterobacteriaceae
No inoculation
5°C, 20 d Fish slices were placed between two layers of edible films and were stored in clean bags
Fish coated with OE-G and RM-G films reduced TVC by 1.99 and 1.54 log CFU/g respectively, on d 16. H2S-reducing bacteria followed a similar pattern. OE and RM had no effect, but CH reduced to ≤103 CFU/g in all cases. Pressurized samples produced undetectable levels of all microorganisms for 20 d, except uncoated sample whose TVC was 105 CFU/g at d 20
Gelatin (G) or in combination with chitosan (CH) films
Clove essential oil (CO)
Total bacterial count (TVC), H2S-producers organisms, luminescent organisms, Pseudomonas, Enterobacteriaceae (EB), and lactic acid bacteria (LAB)
No inoculation
2°C, 11 d Fillets were covered with the G-CH film containing CO, and vacuum-packed in plastic bags
TVC count was 6.1 log CFU/g. Luminescent bacteria reached 6 log CFU/g after 3 d, but later were undetected. H2S producers were completely inhibited from d 3 onwards. LAB and EB increased during storage despite storage temperature
Mixture of L. monocytogenes strains: PSU1, PSU9, F5069, ATCC 19115, and Scott A. 103 CFU/g
Surface-inoculated
4°C, 30 d Samples coated with AL incorporating SL/SD or OF, dried 20 min and stored at 4°C in vacuum sealed bags
Al coatings with 2.4% SL/0.25% SD and OF reduced L. monocytogenes by 3.2 and 4 log CFU/g (slices) and 2.4 and 3 log CFU/g (fillets), respectively, relative to control sample
Vitamin C (VC, 5% w/v) and tea polyphenols (TP, 0.3% w/v)
TVC
No inoculation
21 d, 4°C Bream was dipped in AL-antimicrobial solutions (1 min), air-dried (1 min) and immersed in 2% (w/v) CaCl2 (1 min) to obtain gels. Samples were packed and stored
After 4 d of storage. The TVC of VC and TP decreased by 1.6 and 1.5 log CFU/g, respectively, on day 21
Gelatin extracted from the skin of unicorn leatherjacket (Aluterus monoceros) films
Lemongrass essential oil (LEO) 25% (w/w)
Mesophilic (TVC) and psychrophilic (PS) microorganisms, enterobacteria (EB), and H2S-producing bacteria LAB
No inoculation
12 d, 4°C For each slice, films were placed on both sides. Subsequently, the samples were placed in polystyrene trays wrapped with extensible polypropylene film
TVC of unwrapped sample increased to 7.2 log CFU/g at d 4 reaching 7.9 log CFU/g at d 12. TVC of LEO-film wrapped samples was 5.6 log CFU/g at d 12. PS count for control, G and LEO films was 6.0, 5.5 and 4.0 log CFU/g, respectively. LAB increased to 7.2, 6.7 and 5.9 log CFU/g at the end of storage. LEO-film showed the lowest EB counts (2.2 log CFU/g), as compared to control
Total mesophilic aerobic bacteria (TVC) and psychrotrophic (PS) aerobic bacteria
No inoculation
4°C until end of shelf life. Fish fillets were covered using CH films, wrapped and vacuum packaged using polyethylene bags
The acceptable limit of 6 log CFU/g and 7 log CFU/g for PS and TVC bacteria, respectively, was reached after 25 d at 4°C. Control samples reached this limit after 5 d
11 d, 1-2°C. Fillets were dipped in 1 and 2% CH at 1-2°C for 10 min, drained for 5 min and placed in trays for 24 h, then sealed using HDPE
Eating quality was maintained for 8 and 10 d for 1 and 2% CH respectively, whereas untreated samples lasted 5 d. The limit of 107 CFU/g of TVC was exceeded after 7, 9 and 11 d for untreated, 1% and 2% CH treated samples, respectively
E. coli O157:H7 and L. monocytogenes were spread individually on sample surface and allowed to rest for 30 min
4°C, 15 d Samples wrapped using the BBG film. Samples packed in polyethylene terephthalate film were used as control
After 15 d, populations of E. coli and L. monocytogenes inoculated salmon with the BBG film containing GSE decreased by 0.53 and 0.50 log CFU/g, respectively, compared to the control
