Storage Stability of Omega3enhanced Rainbow Trout Oncorhynchus mykiss: 2 Abusive Storage Temperature

1
Storage Stability of Omega-3-enhanced Rainbow
Trout (Oncorhynchus mykiss) 2 Abusive Storage
Temperature
Y. C. Chen, J. Nguyen, K. Semmens, S. Beamer, and
J. Jaczynski West Virginia University, Animal
Veterinary Sciences


Higher (Plt0.05) moisture contents were observed
only in vacuum packed fillets stored for 6 days.
Regardless of packaging method and storage
length, moisture and total fat contents of
fillets were not (Pgt0.05) affected by flaxseed
oil (FO) and alpha-tocopheryl acetate (a-TA)
supplementations. No (Pgt0.05) interaction for
lipid oxidation and alpha-tocopherol content
between FO and a-TA were observed. A lower
(Plt0.05) alpha-tocopherol contents and higher
TBARS were measured in the FO vacuum-packaged
fillets groups, compared to the no FO group.
Interactions (Plt0.05) between FO and a-TA were
observed in fatty acid profile (FAP), except
total ?-3 FA and EPA of fillets stored for 6
days. Regardless of packaging method, fillets
from basal diet 15 FO 1500ppm a-TA showed
the lowest (Plt0.05) proportion of saturated FA as
well as the highest (Pgt0.05) proportions of
unsaturated FA, total ?-3 FA, and ALA, compared
to those from other treatment groups. The total
?-3 FA and EPA contents of FO group had higher
(Plt0.05) proportion of total fat. However, FO
group or a-TA group had lower (Plt0.05)
proportions of EPA.
Table 1. Moisture (), fat (), alpha-tocopherol
content, and TBARS of trout fillets as affected
by supplementing trout with FO and a-TA
Table 2. P-values of FAP in trout fillets as
affected by supplementing trout with FO and a-TA
(p-value0.05)
The ?-3 FA are essential to health, especially in
heart or brain and vision development during last
three months of pregnancy. Omega-6 fatty acids
(?-6 FA) are also essential. Due to the diet
change, ratio of ?-6 FA and ?-3 FA in our diets
has changed from 1-21 to 10-201. Changing fish
diets may change the composition of fish
fillets. The FO contains the highest
concentration of a-linolenic acid (ALA) compared
to other lipid sources used in fish feeds. Feed
supplemented with FO may increase level of ?-3 FA
in farmed-raised trout fillets. However, higher
contents of ?-3 FA may result in higher oxidation
of fillets. Moreover, the higher temperature of
storage, the more rapid reaction rate of lipid
oxidation. Fat-soluble antioxidants, such as
vitamin E, play an important role in preventing
the oxidation of polyunsaturated FA. The a-TA, a
vitamin E derivative, is usually used as an
antioxidant to reduce lipid oxidation in food.
Animal and human studies suggest that the amount
of vitamin E required to prevent lipid
peroxidation inside the body increases with the
amount of polyunsaturated FA consumed.
Table 3. FAP in trout fillets as affected by
supplementing trout with FO and a-TA

• FO flaxseed oil a-TAalpha-tocopheryl acetate.
• Experimental design 2x2 factorial arrangement of
  treatment in a randomized complete block design.
• Test parameters moisture, ?-tocopherol and total
  fat, FAP, and TBARS.

• Regardless of supplementing basal diet with a-TA
  and packaging method, FO reduced (Plt0.05)
  a-tocopherol content, but increased (Pgt0.05)
  TBARS in fillets. That might be due to reduction
  of lipid oxidation by consuming a-TA.
• Regardless of supplementing basal diets with FO
  and packaging method, a-TA increased (Plt0.05)
  a-tocopherol contents in fillets during 6 days of
  storage.
• Regardless of supplementing basal diets with FO
  or a-TA, vacuum packaged fillets showed higher
  (Plt0.05) a-tocopherol content than aerobic
  packaged ones. A vacuum package hinders oxygen
  contact with fillets. Therefore, a-TA may be
  required at lower concentration to retard lipid
  oxidation.
• There were interactions in FAP (Plt0.05) between
  FO and a-TA, except total ?-3 FA and EPA contents
  of fillets stored for 6 days. Regardless of
  packaging method, fillets from basal diet 15
  FO 1500ppm a-TA had lowest (Plt0.05) proportion
  of saturated FA as well as the highest (Pgt0.05)
  proportions of unsaturated FA, total ?-3 FA, and
  ALA, compared to those from other treatment
  groups.
• Regardless of a-TA and packaging method, FO group
  had higher (Plt0.05) proportion of total ?-3 FA.
  However, lower (Plt0.05) proportions of EPA in the
  FO group or a-TA group were measured.
• The results demonstrated that the vacuum
  packaging reduced lipid oxidation. To maintain
  total ?-3 FA during storage in trout fillets
  obtained from FO supplemented trout, the feed
  should be supplemented with a-TA.

-- no effect (Pgt0.05)
Our objectives were to investigate the effects
of FO and a-TA supplementations on lipid
oxidation, FAP, and alpha-tocopherol content of
trout fillets during storage at 10 ºC.
FO flaxseed oil a-TA alpha-tocopheryl acetate
ALA alpha-linolenic acid EPA Eicosapentaenoic
acid DHA Docosahexaenoic acid

• Regardless of packaging and storage length,
  moisture and fat contents were not (Pgt0.05)
  affected by FO and a-TA supplementations.
  Regardless of supplementing basal diet with FO
  and a-TA, fillets had higher (Plt0.05) moisture at
  6 days of vacuum storage, but did not (Pgt0.05)
  change in fat content under vacuum and aerobic
  conditions.

Fig 2. EPA contents in fillets stored at 10 ºC
for 6 days as affected by supplementing trout
with FO or a-TA
Fig 1. The total Omega-3 (n-3) FA in fillets
stored at 10 ºC for 6 days as affected by
supplementing trout with FO