Evaluation of Extended Live Holding in the Blue Mussel, Mytilus edulis: Changes in Condition, Lipid Profile and Organoleptic Testing
Mussel aquaculture in Newfoundland is expanding. A key challenge for the industry is increasing its understanding of the effects of extended storage of mussels under ambient conditions. Due to transportation complications, freshly harvested product may not be shipped to market immediately, and may require extended holding in a processing facility for up to one month before being processed and sent to the market. Wet storage of mussels under ambient conditions over long periods has been shown to affect meat yield, quality, condition index, stress response and mortality. Determining the optimum period for holding mussels before there is a significant decrease in mussel condition and product quality would benefit the industry.
The objectives of this study are to evaluate the variability in total lipids and fatty acids composition and their relationship with condition index in cultured mussels held in extended wet storage under industrial standards. Additionally, this study evaluates the effect of extended holding on product quality using sensory analysis and organoleptic testing. This is the first study to evaluate both biochemical parameters and final product quality in blue mussels subject to extended wet holding.
Mussels were held for a period of up to one month for fall, winter and spring seasons (2011-2012). Samples were taken at the initial time, 1 week, 2 weeks and 4 weeks into holding. As a field control freshly harvested mussels were sampled at the same time as held mussels. Morphometric measurement
(weight, length, width, depth and crack-force), total lipids and fatty acid content were determined. Twenty-four panelists were also asked to evaluate mussel palatability for both discrimination (Triangle test) and description (7-point scale Hedonic test).
The preliminary morphometric data for the fall season show a progressive loss of dry tissue weight and an increase in water content over the holding period, suggesting that the mussels in holding sustained a situation of energy depletion or starvation. Dry weight: wet weight ratio showed an overall decline over time; after one week the holding and fresh harvest trends separate and held mussels present a lower ratio. During the winter season, the preliminary morphometric data show a more stable dry weight and the dry weight: wet weight ratio increased during holding. However, at the final sampling point of four weeks in holding held mussels still presented a lower ratio than freshly harvested mussels. The preliminary palatability data show that the panelists were unable to determine a significant difference between mussels kept in holding and those freshly harvested, at any sampling time for both fall and winter seasons. Preliminary fatty acid and glycogen content data are still being assessed.