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Chitosan treatments for the fishery industry – Enhancing quality and safety of fishery products

Author(s):

Hélène L. Lauzon, Eyjólfur Reynisson, Aðalheiður Ólafsdóttir

Funded by:

AVS (contract R 13 099-13)

Contact

Aðalheiður Ólafsdóttir

Sensory Evaluation Manager

adalheiduro@matis.is

Chitosan treatments for the fishery industry – Enhancing quality and safety of fishery products

Þessi skýrsla er samantekt þriggja geymsluþolstilrauna þar sem sjávarfang var meðhöndlað með mismunandi kítósan-lausnum, annars vegar um borð veiðiskips (með rækju og þorski) eða eftir slátrun og forvinnslu eldislaxs. Þetta er framhald af skýrslu Matís 41-12 þar sem kítósan-lausnir voru þróaðar og prófaðar á mismunandi fiskafurðum á tilraunastigi hjá Matís. Tilgangur þessa verkefnis var að staðfesta notkunarmögugleika kítósan-meðhöndlunar á sjávarfangi í fiskiðnaðinum. Niðurstöður sýna að styrkleikur kítósan-lausna og geymsluhitastig sjávarfangs hafa áhrif á örverudrepandi virkni og gæðarýrnun fiskafurðanna. Lausnir A og B höfðu takmarkaða virkni í heilum rækjum (0-1°C), en hægari litabreytingar áttu sér stað þar sem skelin tók upp svartan lit. Meðhöndlun laxa (1.4°C) og þorska (-0.2°C) með lausnum C og D hægði verulega á vexti roðbaktería fyrstu 6 dagana sem leiddi til lengingar á fersleikafasanum. Geymsluhitastig þorskfiska hafði áhrif á virkni lausnanna. Þegar þorskur (2-3°C) var geymdur við verri aðstæður og flakaður 6 dögum eftir meðhöndlun, reyndist vera aðeins minna örveruálag á flökunum í upphafi geymslutímans sem skilaði sig lítillega í gæðum afurðanna. Betri geymsluskilyrði eru nauðsynleg til að kámarka virkni kítósan-meðferðar.

This report evaluates the efficiency of different chitosan treatments (A, B, C, D) when used by fishery companies, aiming to reduce seafood surface contamination and promote enhanced quality of fishery products: whole cod, shrimp and farmed salmon. The alkaline conditions establishing in chilled raw shrimp during storage (0-1°C) is the probable cause for no benefits of chitosan treatments A and B used shortly after catch, except for the slower blackening of head and shell observed compared to the control group. On the other hand, salmon treatments C and D were most effective in significantly reducing skin bacterial load up to 6 days post-treatment (1.4°C) which inevitably contributed to the extended freshness period (by 4 days) and shelf life observed. Similarly, freshness extension and delayed bacterial growth on skin was evidenced after 6 days of storage in whole cod (-0.2°C) treated with solution D. For cod stored at higher temperature (2-3°C) and processed into loins on days 3 and 6 posttreatment, a slower microbial deterioration was observed only during early storage of loins. The contribution of chitosan treatments to sensory quality enhancement was not clearly demonstrated in these products. Based on the findings, better chilling conditions should contribute to an enhanced effect of chitosan skin treatment towards quality maintenance.

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Categories
Reports

Evaluation of antibacterial and antioxidative properties of different chitosan products

Author(s):

Hélène L. Lauzon, Patricia Yuca Hamaguchi, Einar Matthíasson

Funded by:

AVS (contract R 11 074‐11)

Evaluation of antibacterial and antioxidative properties of different chitosan products

Í þessari rannsókn voru kannaðir bakteríudrepandi og andoxunar‐  eiginleikar tólf mismunandi kítósanefna frá Primex ehf. Áhrif seigju/mólþunga (150‐360 KDa) og “deacetylation” stigs (A=77‐78%; B=83‐88%; C=96‐100%) á virkni efnanna voru metin. Áhrif sýrustigs (6 og 6.5) og hitastigs (7 og 17°C) á bakteríudrepandi virkni voru einnig skoðuð. Andoxunarvirkni var metin með fjórum aðferðum: oxygen radical absorbance capacity (ORAC), ferrous ion chelating ability, reducing power and DPPH radical scavenging ability. Breytileg andoxunarvirkni fannst hjá mismunandi kítósanefnum. A1 hafði mesta en í raun lítilsháttar afoxandi og bindandi eiginleika, á meðan B3 og B4 voru með hæstu ORAC gildin. Kítósanefni með 96‐100% “deacetylation” voru með mesta in vitro andoxunarvirkni, óháð þeirra mólþunga. Að sama skapi var bakteríudrepandi virkni kítósanefnanna breytileg meðal bakteríutegunda sem voru kannaðar, auk þess sem sýrustigs‐  og hitastigsáhrifin voru mismunandi. Samt sem áður fundust nokkur kítósanefni sem virkuðu vel á allar bakteríutegundir, t.d. A3‐B2‐B3‐C1.

This report evaluates twelve different types of chitosan products manufactured by Primex ehf and tested for their antibacterial and antioxidative properties in a suitable carrier solution. This study examined the effect of viscosity/molecular weight (150‐360 KDa) and degree of deacetylation (A=77‐78%; B=83‐88%; C=96‐100%) on the properties evaluated, as well as the influence of pH (6 and 6.5) and temperature (7 and 17°C) on the antibacterial activity of the chitosan products. The antioxidant activity was evaluated using four assays: oxygen radical absorbance capacity (ORAC), ferrous ion chelating ability, reducing power and DPPH radical scavenging ability. The different chitosan products had different antioxidative properties. A1 had both some reducing and chelating ability, while B3 and B4 had some oxygen radical absorbance capacity. The radical scavenging ability of high DDA (96‐100%) chitosan products was emphasized. Similarly, the antibacterial activity of the different chitosan solutions differed among the bacterial species evaluated as well as pH and temperature conditions. Nevertheless, some products demonstrated antibacterial activity towards all strains tested: mainly A3‐B2‐B3‐C1.

Skýrsla lokuð til 01.01.2014

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