Impact of Reduced Oxygen Packaging on Melanosis Development on Gulf of Mexico White Wild-Plate-Frozen Shrimp (WPFS)Marlena B. Bruno, Dr. Julie A. Lively, Dr. Evelyn G. Watts, Nicholas A. Haddad, Damen Pheiffer

College of Agriculture, Louisiana State University, Baton Rouge, LA

IntroductionLouisiana ranks second in metric tons of seafood landed and the third in dollar value in the US (Fisheries of the United States 2014, 2015). The volume of seafood landing varies from one season to another. During 2015, Louisiana harvested 1,070,318,026 total pounds of seafood. Aquaculture, freshwater and marine fisheries contributed $1.3 billion to the Louisiana economy in 2015, making them the second largest industry in the state (Agriculture: Backbone of Louisiana’s Economy, 2016). The largest seafood commodity in Louisiana is shrimp, landing over 50,000 metric tons annually with a dockside value over $200 million (“National Marine Fisheries Service Annual Landings by Species for Louisiana”, 2015). Melanosis or blackspot development is a natural process caused by polymerization of phenols into insoluble black pigments called melanins. To retard blackspot, a variety of melanosis inhibitors including sulfating agents and 4-hexylresorcinol have been used in combination with iced storage (Montero et al., 2001; Martínez-Alvarez et al., 2005; Nirmal and Benjakul, 2010). During freezing and thawing, inactive Polyphenol Oxidase (PPO) stored in hemocytes and digestive glands is released and activated, resulting in a faster development of melanosis. Blackspot development reduces marketability of food products (Zamorano et al., 2009).

Day: UTVP UTBX TRVP TRBX1 2.10 1.43 1.43 1.332 2.27 2.47 1.37 1.203 3.20 3.13 1.53 1.034 3.10 3.37 1.37 1.435 3.73 3.40 1.53 2.038 3.87 4.03 2.10 1.70

10 3.87 4.07 1.57 1.70Avg. 3.16 3.13 1.56 1.49

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Day: TRVP TRBX1 1.07 1.232 1.33 1.403 1.30 1.504 1.67 1.475 1.73 1.738 1.80 2.10

10 2.33 2.33Avg. 1.60 1.68

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Significance• Identifying an effective packaging technology that retains WPFS quality during storage will

allow fishermen to hold premium quality shrimp until off-season.

Objectives• To evaluate melanosis reduction effectiveness by testing four different packaging

techniques.

ResultsMethods

1. Shrimp free of melanosisinhibitors were purchased direct from fishermen within 12 hours of catch. Half of the shrimp were treated with a 4-hexylresorcinol based formulation.

2. Package shrimp into boxes and plate freeze all in Quality Training Lab.

3. Vacuum pack half of the sample size and use normal box format for the other half.

4. For trial 1, shrimp were divided into four categories. Each treatment category has three replicates.Treated – Vacuum PackedTreated – BoxedUntreated – Vacuum PackedUntreated – Boxed

For trial 2, shrimp were divided into two categories. Each category contained three replicates.Treated – Vacuum PackedTreated – Boxed

5. The shrimp were thawed under cold water after 3 weeksfor Trial 1, and after 3 months for Trial 2.

6. Melanosis observation occurred on days 1-5, 8, & 10. The shrimp were rated on the National Marine Fisheries Service (NMFS) scale of 1 – 5 for melanosis (1 = no black spots present, 3 = unacceptable, 5 = strong blackspot: black heads and shells).

UT shrimp showed first signs for melanosiswithin the first day and became unacceptable at day 3. TR shrimp showed first signs of melanosis at day 5 after thawing, however it never turned unacceptable (Table 1 & Figure 1).

TR shrimp started showing signs of melanosis after 8 days of thawing (Table 2 & Figure 2).

LegendUTVP = Untreated Vacuum PackedUTBX – Untreated BoxTRVP =Treated Vacuum PackedTRBX = Treated Box

Conclusion• 4-hexylresorcinol shows to be a good melanosis inhibitor for plate frozen

shrimp after a freezing and thawing cycle.• Vacuum packing did not show an advantage compared to traditional

methods.• Properly treating shrimp with 4-hexylresorcinol like products, will allow

fishermen the opportunity to plate freeze and hold a premium product until the off season.

• This study will continue to test melanosis development after 6 months of storage in TRVP and TRBX shrimp.

Table 1: Melanosis development after 3 weeks of storage in UTVP, UTBX, TRVP, and TRBX shrimp

Figure 1: Melanosis development after 3 weeks of storage over a 10 day period in UTVP, UTBX, TRVP, TRBX shrimp.

Table 2: Melanosis development after 3 months of storage in TRVP and TRBX.

Figure 2: Melanosis development after 3 months of storage over a 10 day period in TRVP and TRBX shrimp.

In general, we found that 4-hexylresorcinol reduced melanosis development in shrimp after a freezing and thawing cycle (P < 0.05). There was not an advantage of vacuum packing over using standard box format (P > 0.05). In addition, storage of shrimp over a longer period of time did not increase melanosis development (P >0.05).

AcknowledgementsSupport for this project came from Louisiana Sea Grant, SK Grant NA17NMF4270214, and the LSU College of Agriculture Undergraduate Research Program.