musselsalive project: development of best practice and new technology for grading, handling,...
DESCRIPTION
... of mussels for SMEs in the European mussel industry. This power point and videos were presented by Sara Barrento during the Association of Scottish Shellfish Growers 2012 in Oban. In 2011 several mussel farmers were interviewed in Scotland, Ireland and Norway. This presentation addresses two questions raised by the mussel farmers: 1) Can oxygen be maintained above 5 mg/L at flows lower than 6500 L/h? 2)Transport with ice: What is the temperature inside mussels? There are two videos the first video is on slide 34 and the caption is as follows Mussels can survive for extended periods out of water and can be traded for human consumption as live animals. Usually mussels are transported live without water. However, when exposed to air, mussels gape in an attempt to maintain oxygen levels. Gaping occurs when mussels are out of water and is basically the opening of the valves. In this video it can be seen that mussels gape intermittently, and the smaller mussels gape more often, loosing more water than bigger mussels. The footage was taken during a 48 h period, the dark images correspond to the night period. Mussels were kept out of the water in a temperature controlled room set to 18 degrees Celsius. The temperature was chosen because everything happens faster at higher temperatures. The same type of response was shown at 5 degrees, but instead of capturing images during 48 h, the time is then extended to one week, which further demonstrates the importance of keeping low temperatures. The second video is on slide 35 and the caption is as follows: this video shows mussels in an aquarium that were given green microalgae. Mussels start filtrating immediately and at the same time it can be seen that mussels release pseudofaeces. Quite often the mussel foot comes out from the valves and extends. This video is ideal to show how fast mussels filtrate and the importance of filtration during depuration. Many physiological events can be explained and introduced with these images. These videos were supported by The European Commission through the Collaborative Research Project ''MusselsAlive : Development of best Practice and new technology for grading, handling, transportation, conditioning and storage of mussels for SMEs in the European mussel industry".TRANSCRIPT
ASSG 2011
and new technology for ...
Development
of best practice
Keep quality & Reduce waste
Harvest
Consumer
SMEs in the
European mussel industry
Keep quality & Reduce waste
Research
Practices...
different TRANSPORT conditions
different harvesting TECHNIQUES
Companies...
different CLIENTS
different COMMERCIAL CHANNELS
Countries...
different REGULATIONS
different TRADE CHAINS
Conditions of approval Scotland
Specifications The system is approved for the purification of
{species (latin name)} .The system shall consist of a tank measuring 1160 x 980 x 600mm internally containing a minimum water volume of X litres. The maximum capacity of the system shall be X species subject to the loading conditions given
below. The system must be fitted with a 25 watt, or greater, UV
steriliser. Conditions All shellfish must be alive and healthy
before undergoing purification. Purification, without disturbance to shellfish,
must be for a minimum period of 42 hours once the correct
conditions of purification have been achieved.
The total volume of water in the system must be recirculated through the UV
lamps and evenly through the whole system at a rate of at least 20 litres
per minute. After each purification cycle the tank must be drained
down, without causing resuspension of sediment,
before shellfish are disturbed or removed. Seawater should only enter the system via the operating UV system. Seawater should not normally be re-used for more than 2 consecutive weeks. However, extended re-use up to a maximum of one month is permitted where exceptional climatic or other circumstances dictate.
UV lamps must be changed after every 2,500
hours of use. A record of UV usage must be kept for this purpose. UV
lamps must be maintained free of slime and other substances which may impair efficiency of
Conditions of approval
Bulk bins require a minimum flow rate 6500L/h per bin for 250kg of mussels...
to keep oxygen > 5mg/L or 50%
Conditions of approval
Bulk bins require a minimum flow rate 6500L/h per bin for 250kg of mussels...
substantial pumping costs
Can oxygen be maintained
above 5 mg/L at flows lower
than 6500 L/h?
6500L/h
6500L/h 3000L/h
3000L/h 2500L/h
2500L/h
Different Flows Regimes tested for 42 h
How we did it
Calculate the area of the hole to give a
flow of 3000 L/h or 2500 L/h
Q (m/s) = Area of the hole x
√(2xg force x height of the tank)
For each flow we used two tanks as replica
Mussels were harvested and graded as usual
… and placed in the bins
12.6 ̊C
12.6 ̊C
Oxygen sampling
20 hours 24 hours 42 hours
30 min 90 min 7 hours
False Floor
FF
Bottom
Middle MC
Top
Drain
Results Oxygen (mg/L) at 12.6 ̊C
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
9.0
FF Bottom Middle MC Top Drain
Oxy
gen
(m
g/L
)
2500 L/h 3000L/h 6000 L/h 6500 L/h
* *
7.1 mg/L
7.3 mg/L
Drain
7.5 mg/L
7.8 mg/L
7.6 mg/L 6.5 mg/L
7.7 mg/L 7.0 mg/L
Results Oxygen (mg/L)
79 %
81 %
Drain
83%
87 %
85 % 72 %
83 % 77 %
Results Oxygen (%)
Can oxygen be maintained
> 5 mg/L at flows lower
than 6500 L/h? Yes, 2500 L/h and
temperature <12.6⁰C
What is the temperature?
Transport with ice
Photo by Sara Barrento
Temperature during transport
Simulated transport
Logger
ICE
Simulated transport with ice
0.0
2.0
4.0
6.0
8.0
10.0
12.0
14.0
00:00 01:00 02:00 03:00 04:00 05:00 06:00 07:00 08:00
Tem
pe
ratu
re °
C
Hours
Outside box
Top
Middle
Temperature during transport
Temperature inside the mussels Simulated transport
Fake mussel Live mussel
2
4
6
8
10
12
14
10
:32
11
:19
12
:06
12
:53
13
:40
14
:27
15
:14
16
:01
16
:48
17
:35
18
:22
19
:09
19
:56
20
:43
21
:30
22
:17
23
:04
23
:51
00
:38
01
:25
02
:12
02
:59
03
:46
04
:33
05
:20
06
:07
06
:54
07
:41
08
:28
09
:15
10
:02
Tem
pe
ratu
re
C
Live mussel
Fake mussel
Simulated 24h transport without ice
Temperature inside mussels
Temperature inside mussels
ICE
Simulated 48h transport with ice and re-water at 11.7C
Re-water 11.7C
48h simulated transport
0
2
4
6
8
10
12
14
16
18
10
:00
16
:00
00
:00
06
:00
12
:00
18
:00
00
:00
06
:00
12
:00
18
:00
00
:00
06
:00
11
:00
11/02/2012 12/02/2012 13/02/2012 14/02/2012
Tem
pe
ratu
re °
C
Bottom mussel
Middle mussel
Top mussel
Environment
Simulated 48h transport with ice and re-water at 11.7C
Temperature inside mussels
Gaping out of water
26.7
32.5
1.8 0.0
10.0
20.0
30.0
40.0
45.5 mm 56.3 mm 68.3 mm
We
igh
t Lo
ss %
Mussel Length (mm)
vIDEO TRIALS
vIDEO TRIALS