Effect of Grape Seed Extracts on the Melanosis and Quality of Pacific White Shrimp (Litopenaeus vannamei) during Iced Storage

Abstract

The aim of this study was to investigate the effect of grape seed extracts (GSE) at different concentrations (0, 7.5 and 15 g/L) on the melanosis formation and quality of Pacific white shrimp during 9 days of iced storage. The melanosis formation was significantly inhibited and sensory quality was significantly improved in shrimp treated by various concentration of GSE, compared with the control. The increase of pH, total volatile basic nitrogen content and the total bacteria amounts of shrimp treated by 7.5 and 15 g/L of GSE was significantly retarded. However, the melanosis score, total volatile basic nitrogen, and pH values of shrimp treated by 15 g/L of GSE was lower than that treated by 7.5 g/L of GSE. These results suggested that GSE could be used as an effective natural alternative to synthetic antimelanosic agents to inhibit postmortem melanosis and improve the quality of shrimp during iced storage.

Introduction

Due to the high market and nutritional value, shrimp is a very important fisher resource all over the world. However, the shelf life of shrimp was limited due to melanosis and microbiological deterioration. Melanosis or blackening, the formation of black spots in crustaceans, such as shrimp and crabs during postmortem storage, severely damage the market value and usually caused economical loss of these seafood (Kim et al., 2002). Melanosis is the result of the polymerization of phenols by polyphenoloxidase (PPO), also known as phenoloxidase, tyrosinase (EC 1.14.18.1), and cathecoloxidase (EC 1.10.3.1) (Zamorano et al., 2009). Usually, iced storage is routinely used to preserve the quality of the shrimp. However, during refrigerated or iced storage, melanosis still takes place since PPO remains active under these conditions (Gokoglu and Yerlikaya, 2008; Nirmal and Benjakul, 2010).

To retard the melanosis in crustaceans, and ensure perishables have a longer shelf life, antimelanosic agents, such as 4-hexyl-1, 3-benzenediol (4-hexylresorcinol), sulphite-based compounds, and phosphates, have been intensively studied and proved to be effective to inhibit melanosis (Martinez-Alverez et al., 2005, 2008; Thepnuan et al., 2008). However, the use of synthetic compounds to inhibit melanosis in seafood is limited due to increasing regulatory attention and food safety concerns (McEvily et al., 1991). For example, the use of metabisulphite to inhibit melanosis of shrimp could cause the sulfur dioxide residue exceeding problems (Gomez-Guillen et al., 2005). Due to the potential health hazards of chemical additives, natural products, especially natural antioxidants and antimicrobial agents, have been intensively examined as safe alternatives to synthetic compounds (Encarnacion et al., 2010; Maqsood et al., 2013). Recently, a series of studies conducted on the utilization of natural extracts to delay melanosis formation and extend the shelf life of seafood (Nirmal and Benjakul, 2011a, 2012a). The use of phenolic compounds also appears to be a good alternative for sulphiting agent for retarding melanosis in crustaceans (Maqsood et al., 2013).

Grape seed extracts (GSE), rich in polyphenolic compounds, have been reported have many favorable physiological effects on health, including anticarcinogenic activitiy, regulation of body fat and insulin resistance in both animals and humans (Hogan et al., 2001, Kaur et al., 2009). On the other hand, the GSE can be used as a natural food additive due to high antimicrobial and antioxidant activities (Hogan et al., 2001; Kulkarni et al., 2011; Lorenzo et al., 2013; Peng et al, 2010). Gokoglu and Yerlikaya (2008) also found that GSE had inhibition effect on the formation of melanosis of Parapenaeus longirostris stored at 4°C for 3 days by sensory analysis and color measurements. These findings have led to increased interest in GSE. Nevertheless, no study has to date been published to investigate the influence of GSE on shelf life and quality of shrimp during iced storage for a longer time, after all, iced storage is routinely used to preserve the quality of shrimp. In this study, the effect of GSE at different concentrations on the melanosis formation, sensory quality, total bacteria amounts, pH and total volatile basic nitrogen content (TVB-N) of Pacific white shrimp (Litopenaeus vannamei) during iced storage was investigated by sensory evaluation, chemical and microbiological analyses, and the possible mechanism for inhibition of melanosis formation by GSE was discussed.

Materials and Methods

Preparation of grape seed extract  The dried grape seeds were powdered using a mixer grinder and two hundred gram portions of finely-powdered peels were blended with 50% ethanol for 2 h at 20°C in a shaking water bath. The ratio grape seed powder: solvent was 1:10 (w/v). The extracts were through filter paper (Waterman No. 1) and concentrated under vacuum with a rotary evaporator (Eyela, Rikakikai, Tokyo, Japan). The concentrate was dried overnight in an oven at 40°C to form powder which was stored at 4°C until further use. The dipping solutions with different concentration of (0, 7.5 and 15 g/L) were prepared by dissolving GSE in distilled water.

Shrimp collection and treatments  Pacific white shrimp with the size of 50 – 55 shrimps/kg were purchased from a local market in Zhoushan, China. The Pacific white shrimp were kept alive and transported to the College of Food and Medicine, Zhejiang Ocean University, Zhoushan. Pacific white shrimp were dipped into the GSE solutions at different concentrations (0, 7.5 and 15 g/L) at a shrimp/solution ratio of 1:2 (w/v) at 4°C for 30 min. After dipping, the Pacific white shrimp were drained at ambient temperature for 3 min. Another portion of shrimp was treated in 12.5 g/L sodium metabisulfite (SMS) dissolved in distilled water at a ratio of 1:2 (w/ v) for 1 min at 4°C . Ten shrimp from each treatment were covered in plastic bags and stored in ice using a shrimp/ice ratio of 1:2 (w/ w). To maintain the shrimp/ice ratio, molten ice was removed and replaced with an equal amount of ice every 3 days.

Melanosis assessment  Melanosis assessment of Pacific white shrimp was conducted through visual inspection by six panelists using ten-point scoring according to the method of Montero et al. (2001). Panelists were asked to give the melanosis score (0 to 10) for shrimp, where 0 = absent; 2 = slight (up to 20% of shrimps' surface affected); 4 = moderate (20% to 40% of shrimps' surface affected); 6 = notable (40% to 60% of shrimps' surface affected); 8 = severe (60% to 80% of shrimps' surface affected); 10 = extremely heavy (80% to 100% of shrimps' surface affected). Samples were taken for each treatment every 3 days up to 9 days for melanosis assessment.

Sensory evaluation  Sensory evaluation was carried out according to the Chinese National Standard (GB2741-94) at the 0^th and 9^th day during iced storage (Chinese National Standard, 1994).

Microbiological analysis  Microbiological analysis was performed according to the Chinese National Standard (GB4789.2-2010) by measurement of the total bacteria amounts indicated as aerobic plate count (Chinese National Standard, 2010. Twenty-five grams of shrimp were homogenized with 225 mL of 0.85% sterile saline water at 8000 rpm for 1 min. Samples were serially diluted logarithmically in 0.85% sterile saline water. The total aerobic plate count was determined by spread plating samples on nutrient agar and incubating at 36°C for 48 h. Microbial colonies were counted and reported as log CFU/g of fresh weight.

pH determination  The pH values were measured in shrimp according to the method of Lopez-Caballero et al. (2007).

Determination of total volatile basic nitrogen  Total volatile basic nitrogen was determined on steam distillation and TVB-N contents were expressed as mg N/100 g shrimp meat.

Statistical analysis  Statistical analysis was performed using the SPSS package program version 11.5 (SPSS inc. Chicago, IL, USA). Data was analyzed by one-way ANOVA, followed by Turkey's HSD multiple comparison test. The values are reported as means with their standard error for all results. Differences were considered significant at p < 0.05.

Results and Discussion

Effect of GSE treatment on melanosis and quality of Pacific white shrimp during iced storage  The melanosis scores of Pacific white shrimp were shown in Fig. 1. Melanosis scores in all treatments were significantly increased during the 9 days of iced storage and the highest scores for melanosis were found in the control group for all the sampling days. However, a significant difference in scores of melanosis between GSE treatment and control was observed during the 9 days of iced storage. Moreover, the scores of melanosis of Pacific white shrimp treated by 15 g/L of GSE were less than that treated by 7.5 g/L of GSE. On the other hand, the lowest scores for melanosis were obtained in the shrimp treated by SMS.

Fig. 1.

Effect of grape seed extracts on melanosis score of Pacific white shrimp during iced storage. Each data is the mean of three replicates per treatment and time point (mean ± standard error). SMS, sodium metabisulfite; GSE, grape seed extracts.

Our results showed that melanogenesis was significantly inhibited and visual quality was significantly improved in Pacific white shrimp treated with GSE and SMS, which is corresponding with the study conducted by Gokoglu and Yerlikaya (2008) which observed that GSE could inhibit the formation of melanosis of Parapenaeus longirostris stored at 4°C for 3 days. Similar results are also found that other natural extracts or natural compounds could inhibit the melanogenesis of Pacific white shrimp. Lopez-Caballero et al. (2007) and Nirmal et al. (2009a, 2009b, 2010, 2011b, 2012a, 2012b) observed that catechin, ferulic acid and green tea extracts alone or in combination with ascorbic acid could delay the melanosis formation and extend the shelf life of Pacific white shrimp when stored in ice. Similar results were obtained from the extracts from Punica granatum and Leucaena leucocephala which showed the effect of inhibition of melanosis formation in Pacific white shrimp during iced storage (Nirmal and Benjakul, 2011a; Fang et al., 2013) and the extract from the edible mushroom Flammulina velutipes which significantly inhibited the formation of melanosis of shrimp and crab (Encarnacion et al., 2010, 2011a, 2011b, 2012).

It has generally been thought development of melanosis or black spot formation during postharvest of crustaceans attributed to the polymerization of phenolin to an insoluble black pigment, the melanin. Phenol polymerization is mainly initiated by the action of an enzymatic complex-PPO (Alasalvar et al., 2011). Preventive methods for crustacean blackening, which are now in use, can be categorized into physical and chemical treatments. Many studies have focused on PPO inhibition, and various techniques and inhibitor such as heat treatments, high pressure treatments, 4-hexylresorcinol, sulphites and phosphates have been developed and used (Nirmal and Benjakul, 2012b). Natural compounds such as ergothioneine from mushroom, mimosine from lead (Leucaena leucocephala) was shown to inhibit the PPO of shrimp and crab (Nirmal and Benjakul, 2011a, 2011c; Encarnacion et al., 2011a, 2011b, 2012). Phenolic compounds such as catechin and ferulic acid and plant extract rich in polyphenol such as pomegranate peel extract also appears to inhibit the PPO of shrimp and be a good alternative for sulphiting agent for retarding melanosis in crustaceans (Fang et al., 2013; Nirmal and Benjakul, 2012b). It is possible that GSE which is rich in polyphenol could also inhibit the melanosis formation of Pacific white shrimp by inhibition of the PPO activity.

Effect of GSE treatment on sensory quality of Pacific white shrimp during iced storage  The changes in sensory quality of Pacific white shrimp treated by GSE and SMS in comparison with the control were shown in Fig. 2. All samples had the score higher than 9 at the 0^th day of iced storage, and no differences in likeness of samples were found between all treatments. In general, the sensory scores of Pacific white shrimp showed a tendency to decrease during the 9 days of iced storage. However, the decrease rate of sensory scores in Pacific white shrimp was varied with different treatments, which was fastest in the control group for all the sampling days. The decrease of sensory score in Pacific white shrimp treated by GSE and SMS were significantly inhibited, compared with the control and the decrease rate of sensory scores in Pacific white shrimp treated by 15 g/L of GSE was significantly less than that treated by 7.5 g/L of GSE.

The sensory score of Pacific white shrimp without treatment was 5.4 at the 6^th day of iced storage, which reached unacceptable level according to the Chinese National Standard (GB2741-94) (Chinese National Standard, 1994). On the other hand, the sensory score of Pacific white shrimp treated by 15 g/L of GSE reached to 5.1 at the 9^th day of iced storage. These results suggested that the treatment with GSE could improve the sensory properties of Pacific white shrimp.

Fig. 2.

Effect of grape seed extracts on sensory score of Pacific white shrimp during iced storage. Each data is the mean of three replicates per treatment and time point (mean ± standard error). SMS, sodium metabisulfite; GSE, grape seed extracts.

Effect of GSE on the microbiological changes of Pacific white shrimp during iced storage  Changes in total aerobic plate count of Pacific white shrimp during iced storage as influenced by GSE treatment are shown in Fig. 3. In general, an increasing tendency of total aerobic plate count in all samples was observed throughout the storage for 9 days. After treatment with SMS, 7.5 g/L of GSE or 15 g/L of GSE, the lower total aerobic plate count was obtained, in comparison with the control. However, the rise rate of total aerobic plate count varied with different treatments. The increase in total aerobic plate count was highest in the control group for all the sampling days.

Fig. 3.

Effect of grape seed extracts on total aerobic plate count of Pacific white shrimp during iced storage. Each data is the mean of three replicates per treatment and time point (mean ± standard error). SMS, sodium metabisulfite; GSE, grape seed extracts.

The increase in total aerobic plate count of Pacific white shrimp treated by SMS and GSE was significantly inhibited, compared with the control. The total aerobic plate count of shrimp in the control group was 3.59 log CFU/g at the 0^th day and 7.91 log CFU/ g at the 9^th day of iced storage. At the end of storage (9^th day), total aerobic plate count of the control, those treated with SMS, 7.5 g/L of GSE or 15 g/L of GSE, were 5.97, 5.08 and 5.63 log CFU/g, respectively. Grape seeds are considered rich sources of polyphenolic compounds that show antioxidant or antimicrobial effects. Several studies have proved that grape seed extracts by different solvents exhibited antimicrobial activity. Jayaprakasha et al. (2003) observed defatted grape seed powder extracts prepared by acetone:water:acetic acid (90:9.5:0.5) and methanol:water:acetic acid (90:9.5:0.5) could completely inhibited gram-positive bacteria at 850 – 1000 ppm and gram-negative bacteria at 1250 – 1500 ppm concentration. Adámez et al. (2012) found that grape seeds aqueous extracts had antimicrobial activity and that the inhibitory effect of phenolic compounds from seeds extracts was more potent against gram-positive bacteria than gram-negative. Our result indicated that GSE could exert the antimicrobial activity in Pacific white shrimps during iced storage, which is corresponding with those studies.

Effect of GSE treatment on the changes in pH of Pacific white shrimp during iced storage  Fig. 4 showed that the changes in pH of Pacific white shrimp treated by GSE and SMS, compared with the control. pH of the fresh Pacific white shrimp at the 0^th day was 7.33. In general, the increase of pH in all treatments was observed during the 9 days of iced storage. However, the rate of increase of pH varied with different treatments. The increase of pH was highest in the control group for all the sampling days. The rate of increase of pH treated by 15 g/L of GSE was less than that treated by 7.5 g/L of GSE.

Fig. 4.

Effect of grape seed extracts on pH of Pacific white shrimp during iced storage. Each data is the mean of three replicates per treatment and time point (mean ± standard error). SMS, sodium metabisulfite; GSE, grape seed extracts.

The increase in pH of shrimp was due to the accumulation of basic compounds because of activity of bacteria or enzymatic actions (Lopez-Caballero et al., 2007). The increase of pH of shrimp was significantly inhibited by different concentration of GSE treatment in the present study, similar with the effect of green tea extract, pomegranate peel extract and cinnamaldehyde (Fang et al., 2013; Mu et al., 2012). However, the inhibition in rise of pH of shrimp was less effective than SMS in our study. Shamshad et al. (1990) reported that shrimp (Penaeus merguiensis) was not acceptable when the pH was greater than 7.6. These results suggested that GSE might play a role in retarding quality loss of shrimp, in which the spoilage or decomposition could be lowered.

Effect of GSE treatment on the changes in TVB-N of Pacific white shrimp during iced storage  TVB-N is a common and important indicator of the quality of Pacific white shrimp because the increased TVB-N value is related to microbial spoilage and the activity of endogenous enzymes (Bak et al., 1999). Fig. 5 showed that the TVB value of Pacific white shrimp treated by GSE and SMS, compared with the control. In general, the TVB-N value of Pacific white shrimp in both control and treatment was markedly increased during the 9 days of iced storage. However, the rise rate of TVB-N value varied with different treatments. The increase in TVB-N value was highest in the control group for all the sampling days and was significantly inhibited after treatment with SMS and GSE. On the other hand, the rise rate of TVB-N value of Pacific white shrimp treated by 15 g/L of GSE was less than that treated by 7.5 g/L of GSE.

Fig. 5.

Effect of grape seed extracts on the total volatile basic nitrogen content of Pacific white shrimp during iced storage. Each data is the mean of three replicates per treatment and time point (mean ± standard error). SMS, sodium metabisulfite; GSE, grape seed extracts.

According to the Chinese National shrimp sanitary standard, the TVB-N value of fresh shrimp should be < 300 mg/100 g (GB2741-94) (Chinese National Standard, 1994). The initial TVB-N value of Pacific white shrimp was 10.2 mg/100 g. For the control sample, the TVB-N value was 52.5 mg/100 g at the 6^th day of storage and exceeded the acceptable limit of 300 mg/100 g. The TVB-N value of shrimp treated by 15 g/L GSE was 36.7 mg/100 g at the 9^th day of iced storage. Similar results were obtained from other studies which reported that the TVB-N value of Pacific white shrimp treated with ferulic acid and cinnamaldehyde was significantly decreased (Shamshad et al., 1990; Nirmal and Benjakul, 2009a).

Conclusions

The effect of GSE at different concentrations on the melanosis formation and quality of Pacific white shrimp during iced storage were investigated in the present study. The melanosis score was significantly inhibited and sensory quality was significantly improved in Pacific white shrimp treated with various concentration of GSE, compared with the control. The increase of pH and TVB-N value was also significantly inhibited in Pacific white shrimp treated with various concentration of GSE, compared with the control. The increase in the total bacteria amounts of shrimp treated by 7.5 and 15 g/L of GSE during was retarded during iced storage for up to 9 days, in comparison with the control and those treated with SMS. The melanosis score, TVB-N and pH values of Pacific white shrimp treated by 15 g/L of GSE was lower than that treated by 7.5 g/L of GSE during the 9 days of iced storage. These results suggested that GSE could be used as an effective natural alternative to synthetic antimelanosic agents to inhibit postmortem melanosis in shrimp.

Acknowledgement This work was supported by Joint Key Laboratory of Aquatic Products Processing Technology of Zhejiang Province (No. 2011E10002).

References

•  Adámez,  J.D.,  Samino,  E.G.,  Sánchez,  E.V., and González- Gómez,  D. (2012). In vitro estimation of the antibacterial activity and antioxidant capacity of aqueous extracts from grape-seeds (Vitis vinifera L.). Food Con., 24, 136–141.
•  Alasalvar,  C.,  Shahidi,  F.,  Miyashita,  K., and  Wanasundara,  U. (2011). Handbook of Seafood Quality, Safety and Health Applications. Blackwell Publishing Ltd.
•  Bak,  L.S.,  Andersen,  A.B.,  Andersen,  E.M., and  Bertelsen,  G. (1999). Effect of modified atmosphere packaging on oxidative changes in frozen stored cold water shrimp (Pandalus borealis). Food Chem., 64, 169–175.
• Chinese National Standard (GB2741-94) (1994). Hygienic standard for sea shrimp. Chinese National Hygiene Ministry, Beijing.
• Chinese National Standard (GB4789.2-2010) (2010). Microbiological examination of food hygiene: detection of aerobic bacterial count. Chinese National Hygiene Ministry, Beijing.
•  Encarnacion,  A.B.,  Fagutao,  F.,  Shozen,  K.,  Hirono,  I., and  Ohshima,  T. (2011a). Biochemical intervention of ergothioneine-rich edible mushroom (Flammulina velutipes) extract inhibits melanosis in crab (Chionoecetes japonicus). Food Chem., 127, 1594–1599.
•  Encarnacion,  A.B.,  Fagutao,  F.,  Hirayama,  J.,  Terayama,  M.,  Hirono,  I., and  Ohshima,  T. (2011b). Edible Mushroom (Flammulina velutipes) extract inhibits melanosis in Kuruma shrimp (Marsupenaeus japonicus). J. Food Sci., 76, C52–58.
•  Encarnacion,  A.B.,  Fagutao,  F.,  Hirono,  I.,  Ushio,  H., and  Ohshima,  T. (2010). Effects of ergothioneine from Mushrooms (Flammulina velutipes) on melanosis and lipid oxidation of Kuruma Shrimp (Marsupenaeus japonicus). J Agric. Food Chem., 58, 2577–2585.
•  Encarnacion,  A.B.,  Fagutao,  F.,  Jintasataporn,  O.,  Worawattanamateekul,  W.,  Hirono,  I., and  Ohshima,  T. (2012). Application of ergothioneine-rich extract from an edible mushroom Flammulina velutipes for melanosis prevention in shrimp, Penaeus monodon and Litopenaeus vannamei. Food Res. Int., 45, 232–237.
•  Fang,  X.B.,  Sun,  H.Y.,  Huang,  B.Y., and  Yuan,  G.F. (2013). Effect of pomegranate peel extract on the melanosis of Pacific white shrimp (Litopenaeus vannamei) during iced storage. J. Food Agric. Environ., 11, 105–109.
•  Gokoglu,  N. and  Yerlikaya,  P. (2008). Inhibition effects of grape seed extracts on melanosis formation in shrimp (Parapenaeus longirostris). Int. J. Food Sci. Technol., 43, 1004–1008.
•  Gomez-Guillen,  M.C.,  Martinez-Alverez,  O.,  Llamas,  A., and  Montero,  P. (2005). Melanosis inhibition and SO₂ residual levels in shrimps (Parapenaeus longirostris) after different sulfite-based treatments. J. Sci. Food Agri., 85, 1143–1148.
•  Hogan,  S.,  Canning,  C.,  Sun,  S.,  Sun,  X.,  Kadouh,  H., and  Zhou,  K. (2001). Dietary supplementation of grape skin extract improves glycemia and inflammation in diet-induced obese mice fed a Western high fat diet. J. Agric Food. Chem., 59, 3035–3041.
•  Jayaprakasha,  G.K.,  Tamil,  S., and  Sakariah,  K.K. (2003). Antibacterial and antioxidant activities of grape (Vitis vinifera) seed extracts. Food Res. Int., 36, 117–122.
•  Kaur,  M.,  Agarwal,  C., and  Agarwal,  R. (2009). Anticancer and cancer chemopreventive potential of grape seed extract and other grape-based products. J. Nutr., 139, 1806S–1812S.
•  Kim,  J.,  Marshall,  M.R., and  Wei,  C. (2002). Polyphenoloxidase in seafood enzymes: utilization and influence on postharvest seafood quality. In “Seafood Enzymes,” ed. by N. Haard and B. Simpson. Marcel Dekker Inc., New York. pp 271–315.
•  Kulkarni,  S.,  DeSantos,  F.A.,  Kattamuri,  S.,  Rossi,  S.J. and  Brewer,  M.S. (2011). Effect of grape seed extract on oxidative, color and sensory stability of a pre-cooked, frozen, re-heated beef sausage model system. Meat Sci., 88, 139–144.
•  Lopez-Caballero,  M.E.,  Martinez-Alvarez,  O.,  Gomez-Guillen,  M.C., and  Montero,  P. (2007). Quality of thawed deepwater pink shrimp (Parapenaeus longirostris) treated with melanosis-inhibiting formations during chilled storage. Int. J. Food Sci. Technol., 42, 1029–1038.
•  Lorenzo,  J.M.,  González-Rodríguez,  R.M.,  Sánchez,  M.,  Amado,  I.R., and  Franco,  D. (2013). Effects of natural (grape seed and chestnut extract) and synthetic antioxidants (buthylatedhydroxytoluene, BHT) on the physical, chemical, microbiological and sensory characteristics of dry cured sausage “chorizo”. Food Res. Int., 54, 611–620.
•  Maqsood,  S.,  Benjakul,  S., and  Shahidi,  F. (2013). Emerging role of phenolic compounds as natural food additives in fish and fish products. Crit. Rev. Food Sci. Nutr., 53, 162–179.
•  Martínez-Álvarez,  O.,  Lopez-Caballero,  M.E., and  Montero,  P. (2005). 4-Hexylresorcinol-based formulation to prevent melanosis and microbial growth in chilled tiger prawns (Marsupenaeus japonicas) from aquaculture. J. Food Sci., 70, 415–422.
•  Martinez-Alverez,  O.,  Gomez-Guillen,  M.C., and  Montero,  P. (2008). Chemical and microbial quality indexes of Norwegian lobsters (Nephrops norvegicus) dusted with sulphites. In.t J. Food Sci. Technol., 43, 1099e1110.
•  McEvily,  A.J.,  Iyengar,  R., and  Otwell,  S. (1991). Sulfite alternative prevents shrimp melanosis. Food Technol., 45, 80–86.
•  Montero.  P,  Ávalos.  A., and  Pérez-Mateos,  M. (2001). Characterization of polyphenoloxidase of prawns (Penaeus japonicus). Alternatives to inhibition: additives and high-pressure treatment. Food Chem., 75, 317–324.
•  Mu,  H.L.,  Chen,  H.J.,  Fang,  X.J.,  Mao,  J.L., and  Gao,  H.Y. (2012). Effect of cinnamaldehyde on melanosis and spoilage of Pacific white shrimp (Litopenaeus vannamei) during storage. J. Sci. Food Agric., 92, 2177–2182.
•  Nirmal,  N.P. and  Benjakul,  S. (2009a). Effect of ferulic acid on inhibition of polyphenoloxidase and quality changes of Pacific white shrimp (Litopenaeus vannamei) during iced storage. Food Chem., 116, 323–331.
•  Nirmal,  N.P. and  Benjakul,  S. (2009b). Melanosis and quality changes of Pacific white shrimp (Litopenaeus vannamei) treated with catechin during iced Storage. J. Agric. Food Chem., 57, 3578–3586.
•  Nirmal,  N.P. and  Benjakul,  S. (2010). Effect of catechin and ferulic acid on melanosis and quality of Pacific white shrimp subjected to freeze-thawing prior refrigerated storage. Food Con., 21, 1263–1271.
•  Nirmal,  N.P. and  Benjakul,  S. (2011a). Inhibition of melanosis formation in Pacific white shrimp by the extract of lead (Leucaena leucocephala) seed. Food Chem., 128, 427–432.
•  Nirmal,  N.P. and  Benjakul,  S. (2011b). Retardation of quality changes of Pacific white shrimp by green tea extract treatment and modified atmosphere packaging during refrigerated storage. Int. J. Food Microbiol., 149, 247–253.
•  Nirmal,  N.P. and  Benjakul,  S. (2011c). Inhibitory effect of mimosine on polyphenoloxidase from Cephalothoraxes of Pacific white shrimp (Litopenaeus vannamei). J. Agric. Food Chem., 59, 10256–10260.
•  Nirmal,  N.P. and  Benjakul,  S. (2012a). Effect of green tea extract in combination with ascorbic acid on the retardation of melanosis and quality changes of Pacific white shrimp during iced storage. Food Biopro. Technol., 5, 2941–2951.
•  Nirmal,  N.P. and  Benjakul,  S. (2012b). Inhibition kinetics of catechin and ferulic acid on polyphenoloxidase from cephalothorax of Pacific white shrimp (Litopenaeus vannamei). Food Chem., 131, 569–573.
•  Peng,  X.F.,  Ma,  J.Y.,  Cheng,  K.W.,  Jiang,  Y.,  Chen,  F., and  Wang,  M.F. (2010). The effects of grape seed extract fortification on the antioxidant activity and quality attributes of bread. Food Chem., 119, 49–53.
•  Shamshad,  S.I.,  Riaz,  M.,  Zuber,  R.,  Zuberir,  R., and  Qadri,  R.B. (1990). Shelf life of shrimp (Penaeus merguiensis) stored at different temperatures. J. Sci. Food Agric., 42, 235–247.
•  Thepnuan,  R.,  Benjakul,  S., and  Visesssanguan,  W. (2008). Effect of pyrophosphate and 4-hexylresorcinol pretreatment on quality of refrigerated white shrimp (Litopenaeus vannamei) kept under modified atmosphere packaging. J. Food Sci., 73, S124–S133.
•  Zamorano,  J.P.,  Martinez-Alverez,  O.,  Montero,  P., and  Gómez-Guillén,  M.C. (2009). Characterization and tissue distribution of polyphenoloxidase of deepwater pink shrimp (Parapenaeus longirostris). Food Chem., 112, 104–111.