Technical Factors Influencing to Production of Galangal-Pickled Shrimp ( Litopenaeus Vannamei )

White shrimp (Litopenaeus vannamei) is a very important food due to high protein content and nutritional value. Galanga (Alpinia galanga) is highly evaluated as their specific flavor and aroma as well as plenty healthy effects. Fermentation is considered as a common approach in food storage; it contributes an essential duty in improvement of nutritional and functional characteristic of foodstuff. Pickled shimp has good source of peptides and amino acids. Therefore, objective of this research focused on different chemical/ technical aspects such as the effect of NaCl, CaCl2, sugar and ethanol concentration used for primary treatment; galangal ratio mixing with shrimp, fermentation temperature and time influencing to the amino acid content, pH, water activity and sensory characteristics galangal-pickled shrimp. Results revealed that 15% of NaCl, 2.0% of CaCl2, 10% of sucrose, 8% of ethanol addition together with 10% sliced galangal in shrimp mixture; fermentation at 28oC for 28 days, the final galangal-pickled shrimp had the good a pleasant taste and appearance. This delicious pickled shrimp was highly welcomed by customers.


INTRODUCTION
White shrimp (Litopenaeus vannamei) is one of the key brackish water species in Vietnamese shrimp farming.Vietnamese farmers move away from farming black tiger shrimp (Penaeus monodon) and change to the cheaper white shrimp (Litopenaeus vannamei).Regarding to nutritive compostion of raised white leg shrimp Litopenaeus vannamei, it has good source of protein, carbohydrate, lipid, moisture and ash, calcium, sodium, potassium, manganese, copper, chromium 1 .Shrimps have low fat, less cholesterol and high PUFA content 2 .
Galanga (Alpinia galanga) is a plant in the ginger family.Galangal is highly evaluated for their specific flavor and aroma.Various parts of this plant are utilized in the treatment of many diseases 3 .
Alpinia galanga contained flavonoids and volatile oil 4,5 .Galangal is used as an alternative to replace antibiotics applied in shrimp farming 6 .
Fermented products from white shrimp (Litopenaeus vannamei) such as fermented shrimp paste, pickled shrimp are widely consumed in Vietnam.Fermented shrimps imparted delicacy and high nutritional properties 7 .Regarding to production of fermented shrimp paste, there were serveral outstanding researches.Shrimp was mixed with salt to ferment shrimp paste 8 .Lentibacillus kapialis sp.produced a red color in sodium chloride during shrimp paste fermentation 9 .Fermented shrimp products could be considered as umami 10 .Quality characteristics in different shrimp paste were compared 11 .The changes in the biochemical, nutritional, and sensory properties of the shrimp paste during fermentation were studied 12 .
The seafood pickle has good composition of protein, glycogen and minerals compared with vegetable one 13,14,15 .There were several researches mentioned to the production of pickle seafood.Total viable count in prawn pickle in the range of 103-105 per g was reported 16 .Microorganisms associated with spoilage of prawn pickle was studied 17 .Microbiological characteristics of prawn pickle.Staphylococcus was reported in spoiled prawn pickle was examined 18 .The pickled prawn was produced 19 .The firmness in prawns (Machrobrachium rosenbergii) marinated in NaCl and acidity was evaluated 20 .The white shrimp (Litopenaeus vannamei) was marinated with green curry to produced shrimp paste marinade 21 .The effects of different temperature and time during pasteurization on marinated green curry shrimp were examined 22 .However, there was not any research mentioned to production of pickle white shrimp (Litopenaeus vannamei).Therefore, objective of this research focused on different technical aspects such as the effect of NaCl, CaCl 2 , sucrose and ethanol concentration used for primary treatment; galangal ratio mixing with shrimp, fermentation temperature and time influencing to the amino acid content, pH, water activity and sensory characteristics galangal-pickled shrimp.

Shelf-life of the galanga-pickled white shrimp (Litopenaeus vannamei) during storage
Galanga-pickled white shrimp (Litopenaeus vannamei) products were kept in ambient temperature condition (28±2 o C).Amino acid (g/100g), pH, water activity (aw), sensory score were used as quality indicators by sampling in 3 months interval for 12 months.

Physico-chemical, microbial and sensory analysis
Amino acid was measured by using an amino acid analyzer.pH of samples was measured using a pH meter.Water activity was assessed by using a water activity meter.Sensory score of fermented shrimp (Litopenaeus vannamei) paste was assessed by a group of panelist using the 9-point hedonic scale.

Statistical analysis
The experiments were performed in triplicate.Statistical analysis was based on the Startgraphics.
Rainbow Sardines and mackerel were pickled according to this cure, salt ratio adopted being 1:3 by weight of fish 23 .Salt concentration 1.0-3.5% and acetic acid 1-2%, the stability of pickled fish was low 24 .The firmness of marinated prawns (Machrobrachium rosenbergii) in various NaCl and acidity was evaluated.CaCl 2 and citrate solutions sightly accelerated the firmness of cooked prawn comparing with control.Tripolyphosphate didn't show effect while CaCl 2 , citric acid and lemon juice accelerated the muscle firmness 20 .
Nowa days people prepared seafood pickle by using organic solution with NaCl and spices 25 .Green curry paste marinade for white shrimp (Litopenaeus vannamei) with additional amount of garlic was was investigated to satisfy consumer acceptability 21 .The effects of different temperature and time during pasteurization of marinated shrimp in green curry were evaluated.The treated shrimp was mixed with green curry paste with shrimp to green curry paste ratio 2:1 (w/w) 22 .
Fermentation was one of the preservative approaches to maintain the stability of the seafood storage for long time 26 .Shrimp paste was produced by mixing with salt to ferment at ambient temperature 8 .

Shelf-life of the galanga-pickled white shrimp (Litopenaeus vannamei) during storage
Galanga-pickled white shrimp (Litopenaeus vannamei) products were kept in ambient temperature condition (28±2 o C).Amino acid (g/ 100g), pH, water activity (aw), sensory score were used as quality indicators by sampling in 3 months interval for 12 months.From Table 7, quality of galanga-pickled white shrimp (Litopenaeus vannamei) was nearly stable at ambient temperature (28±2 o C) during 12 months of storage.Note: the values were expressed as the mean of three repetitions; the same characters (denoted above), the difference between them was not significant (α = 5%).
During pickling process, a large quantity of specific amino acid was produced.Seafood pickle was safe without any toxic bacteria and maintaining durable stability over 6 months at room temperature 16 .The preparation of pasteurized marinated shrimp in green curry paste was safe for human consumption until the end of storage period for 15 days at 0-3°C 27 .

CONCLUSION
Pickling is one of the easy and safe means of shrimp preservation.Pickled shrimps create essential peptids and amino acids through autolytic and fermented reaction during the fermentation.However there was not any research mentioned to production of pickle white shrimp (Litopenaeus vannamei).The main production of this product is salt adding, fermenting, and curing.We have successfully examined different factors affecting to production of galanga-pickled white shrimp (Litopenaeus vannamei).By preserving under ambient temperature (28±2 o C), the galangal-picked shrimp could be maintained shelflife for 12 months without any preservative.This simple technology can be easily approached to process in household scale.