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CONFERENCE PAPER
Year : 2021  |  Volume : 11  |  Issue : 4  |  Page : 298-302

Thermophysical Properties of Brackish Water Shrimp (Litopenaeus vannamei) for Process Design and Optimization


1 Department of Fish Process Engineering, College of Fisheries Engineering, Tamil Nadu Dr J. Jayalalithaa Fisheries University, Nagapattinam, Tamil Nadu, India
2 Tamil Nadu Open University, Chennai, Tamil Nadu, India

Date of Submission12-May-2021
Date of Decision30-May-2021
Date of Acceptance09-Jul-2021
Date of Web Publication26-Oct-2021

Correspondence Address:
N. Manimehalai
Department of Fish Process Engineering, College of Fisheries Engineering, Tamil Nadu Dr J. Jayalalithaa Fisheries University, Nagapattinam, Tamil Nadu
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/ijnpnd.ijnpnd_28_21

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   Abstract 


The proximate compositions, moisture (74.2%), protein (28.07%), ash (2.62%), lipid (3.39%), and carbohydrate (4.39%) of brackish water shrimp (Litopenaeus vannamei) were determined. The density, specific heat, thermal conductivity, thermal diffusivity, and latent heat obtained as functions of the proximate composition of the shrimp and found to be 1110 kg/m3, 394 kJ/kgK, 0.5113 W/mK, 1.1773 × 10−6 m2/s, and 256.39 kJ/kg, respectively. The thermophysical values obtained were correlated with the proximate composition value. Correlation analysis reveals that specific heat (0.83), thermal conductivity (perpendicular model) (0.99), and latent heat (0.12) have positive correlation with protein content of shrimp. On the contrary, thermal diffusivity (−0.92) and thermal conductivity (parallel model) (−0.99) have negative correlation with protein content of shrimp. Further, latent heat of shrimp has a weak positive correlation (0.12) with protein content of shrimp and strong positive correlation with carbohydrate (0.82), fat (0.94), and water (1.0). Thermal conductivity (perpendicular model) has weak positive correlation with fat (0.18) and water (0.19), and has strong positive correlation with protein (0.99) and ash (0.81). Shrimp density has strong correlation with protein (0.98) followed by ash (0.86). Heat may be transferred better across the fibers of the shrimp than along the fiber. Context: Shrimp is one of the most valuable sources of high-grade protein among the seafood category. Shrimp has healthy fat a unique source of essential nutrients, including long-chain omega-3 fatty acids, iodine, vitamin D, and calcium. The global shrimp production has increased at a compound annual growth rate (CAGR) of 3.2% during the period 2011 to 2017. High market demand and consumer preference for shrimp food are attributed due to the attractive and sleek appearance, substantial flesh, ease of preparation for processing (mainly due to absence of scales), etc. With the potential and promise of further increases in production, it is essential to provide a firm base for development of technologies suitable for the value-added products from shrimp to further enhance its market expansion. Understanding on thermal properties of foods plays an important role in the design and prediction of heat transfer operations during the handling, processing, canning, storing, and distribution of foods. In addition, they are fundamentally important in mathematical modeling studies for the design and optimization of food-processing operation involving heat and mass transfer. Aims: The aim of the present study is to determine some thermophysical properties of shrimp as a function of its proximate composition to provide data for the development of appropriate equipment and processing technology for brackish water shrimp (L. vannamei). Settings and design: Proximate composition of the brackish water shrimp (L. vannamei) was measured. Prediction equations were developed to predict the thermophysical properties of shrimp. Correlation matrix was prepared to understand the dependence of proximate composition and thermophysical properties of shrimp. Materials and methods: Shrimp (L. vannamei) were obtained from an aquaculture farm in Nagapattinam. Shrimp were handled in accordance with the Codex General Principles of Food Hygiene (CAC/RCP 1-1969) and Code of Practice for Fish and Fishery Products (CAC/RCP 52-2003). The Kjeldahl method was performed according to method 981.10 of the AOAC International. Total lipids in tissue sample were extracted and analyzed by the method. Water content was determined by oven drying at 105°C, and ashing by incineration in a muffle furnace at 525°C. Carbohydrate content was determined by difference method as given in the following equation: % Carbohydrate = 100–% (Crude protein + Total fat + Ash) × 100. Comprehensive models were used predict volume and thermal properties. Statistical analysis used: Correlation matrix of proximate composition and the thermophysical properties of shrimp were prepared to understand the dependence of thermophysical properties with the proximate composition of shrimp. Results: The predicted values of the thermophysical properties of farmed shrimp were in accordance with the already published values. The density of the shrimp is slightly higher side when compared with water alone, indicating the influence of proximate composition. Correlation matrix thus prepared, better explains dependence of thermophysical properties (specific heat, thermal conductivity, thermal diffusivity, latent heat, and density) with the proximate compositions (moisture, protein, ash, lipid, and carbohydrate) of brackish water shrimp (L. vannamei).Shrimp is “nature’s superfood,” an important source of proteins and healthy fat, and a unique source of essential nutrients, including long-chain omega-3 fatty acids, iodine, vitamin D, and calcium. The knowledge of its engineering properties is essential to its processing and preservation to increase its value as food. The thermophysical data obtained in this study could be used as input in heat transfer calculations and to establish critical control points during the drying, freezing, and thermal processing of shrimp meat.

Keywords: Density, thermal conductivity, thermal diffusivity, shrimp, specific heat


How to cite this article:
Manimehalai N, Karthickumar P, Rathnakumar K. Thermophysical Properties of Brackish Water Shrimp (Litopenaeus vannamei) for Process Design and Optimization. Int J Nutr Pharmacol Neurol Dis 2021;11:298-302

How to cite this URL:
Manimehalai N, Karthickumar P, Rathnakumar K. Thermophysical Properties of Brackish Water Shrimp (Litopenaeus vannamei) for Process Design and Optimization. Int J Nutr Pharmacol Neurol Dis [serial online] 2021 [cited 2021 Dec 3];11:298-302. Available from: https://www.ijnpnd.com/text.asp?2021/11/4/298/329199



Key Messages: Comprehensive mathematical models to predict thermophysical properties of brackish water shrimp (L. vannamei) based on biochemical compositions.


   Introduction Top


India is the largest producer of brackish water shrimp in the world and accounts for nearly 6% of the global shrimp production.[1] Shrimp has an important role to play in nutrition and food security. Shrimp is “nature’s superfood,” an important source of proteins, healthy fat including long-chain omega-3 fatty acids, and a unique source of essential nutrients, such as iodine, vitamin D, and calcium. The global shrimp production has increased at a compound annual growth rate (CAGR) of 3.2% during the period 2011 to 2017.[2] The top five producers are from Asia, namely China, India, Indonesia, Vietnam, and Thailand, account for more than 80% of the total global shrimp production. Native giant tiger prawn (Penaeus monodon) and exotic white leg shrimp (Penaeus vannamei) are the two major shrimp varieties produced in India. High market demand and consumer preference for shrimp food is attributed due to the attractive and sleek appearance, substantial flesh, ease of preparation for processing (mainly due to absence of scales), etc. With the potential and promise of further increases in production, it is essential to provide a firm base for development of technologies suitable for the value added products from shrimp to further enhance its market expansion. The engineering design of food processes and equipment requires the knowledge of basic physicochemical and engineering properties of food materials.[3] Thermal properties of foods are classified as thermodynamic properties (enthalpy and entropy), heat transport properties [thermal conductivity (k) and thermal diffusivity (α)], and thermophysical properties [density (ρ), specific heat (Cp), latent heat, freezing point, boiling point, mass, porosity, and viscosity]. Understanding on thermal properties of shrimp plays an important role in the design and prediction of heat transfer operations during the handling, processing, canning, storing, and distribution of shrimp. In addition, they are fundamentally important in mathematical modeling studies for the design and optimization of shrimp processing operation involving heat and mass transfer. Latent heat of shrimp plays an important role in freezing, crystallization, evaporation, and dehydration process. Specific heat is required to determine the quantity of energy that need to be added or removed during thermal processing. Thermal conductivity and thermal diffusivity describe the heat transfer characteristics of shrimp and will influence how quickly the shrimp product heats or cools during thermal processing.

Mechanization of shrimp value-addition activities in India could be traced very little due to insufficient data on the thermophysical properties of these high value products. This could be due to the nonavailability of standard equipment for measuring the thermophysical properties of brackish water shrimp. On the other hand, standard equipment and protocols are available for measuring the proximate composition of the brackish water shrimp.

Hence, the present study aims in determining the thermophysical properties of shrimp as a function of its proximate composition. This could provide the data for the development of appropriate equipment and processing technology for brackish water shrimp (Litopenaeus vannamei). The objectives of the study were to determine the proximate composition of the brackish water shrimp, to fit the proximate composition value into the existing model and to find out the correlation coefficient between thermophysical properties and proximate composition of the brackish water shrimp.


   Subjects and Methods Top


Sample collection and preparation

Shrimp (L. vannamei) were obtained from an aquaculture farm in Nagapattinam. Shrimp once harvested were dumped on sufficient quantity of crushed ice spread evenly across the crate to ensure that the pristine quality of live condition is secured. Another layer of ice is spread evenly on the shrimp to render all shrimp die due to chill shock/cold shock owing to the temperature of the body quickly reaching to 0° or 1° temperature. The shrimp were sorted, cleaned, and washed in potable water before the head and shells were removed and discarded. The shrimp were deveined and subjected to proximate composition analysis.

Proximate composition

The Kjeldahl method was performed according to method 981.10 of the AOAC International.[4] Approximately 1 g of raw material was hydrolyzed with 15 mL concentrated sulfuric acid (H2SO4) containing two copper catalyst tablets in a heat block at 420°C for 2 hours. After cooling, H2O was added to the hydrolysates before neutralization and titration. The amount of total nitrogen in the raw materials was multiplied with species-specific conversion factors[5],[6],[7] to determine total protein content. The species-specific conversion factor was 5.6 for shrimp.[6] Total lipids in tissue sample were extracted according to the method defined by Bligh and Dyer[8] which is then modified to Folch et al.’s method.[9] One hundred gram muscle tissue was cut from the fresh shrimp, rinsed with distilled water, and dried to constant weight in a drying oven (60°C, 24 hours). Dried samples were minced in a glass blender, homogenized with chloroform: methanol mixture (2:1 V/V), mixed in a vortex mix in 2800 rpm, and filtered. The extract was shaken and equilibrated with ¼ of its volume of a saline solution. The extracted lipids were concentrated by a rotary evaporator. Lipids were stored in sealed vials. Extracted lipids were weighed in vials using a microelectronic balance (±0.001 mg) to calculate the total lipid content. The same procedure was repeated with three replicates of shrimp and the mean value was computed. Water content was determined by oven drying at 105°C, and ashing by incineration in a muffle furnace at 525°C. Carbohydrate was determined by difference as in equation (1):



Density

The density of shrimp was determined from the composition of the shrimp[10] using the relationship in equation (2):



where ρs is the density of the shrimp meat; Vw, Vp, Vf, Va, and Vc are the volume fractions for water, protein, fat, ash, and carbohydrate constituents in the shrimp, respectively and ρw, ρp, ρf, ρa, and ρc are the densities for the water, protein, fat, ash, and carbohydrate components in the shrimp meat, respectively. The densities of solid constituents, disregarding any internal pores, have been reported[11] as follows: ρw (water) = 1000 kg/m3, ρp (protein) = 1400 kg/m3, ρf (fat) = 900–950 kg/m3, ρa (ash) = 2160 kg/m3, and ρc (starch) = 1500 kg/m3.

Volume fraction for protein constituent in the shrimp meat was determined as in equation (3):



where mw, mp, mf, ma, and mc are the mass fractions for water, protein, fat, ash, and carbohydrate constituents in the meat, respectively. Vw, Vf, Va, and Vc were determined as for Vp in equation (3) by substituting their respective mass fractions and densities.

Thermal properties

Comprehensive model[9] used to predict specific heat of the shrimp based on composition and temperature. Equation (4) was used for determination of specific heat (Cp):



where Cw, Cp, Cf, Cc, Ca are the specific heats for water, protein, fat, carbohydrate, and ash constituents in the shrimp, respectively. Folch et al.[9] reported the values for the specific heats of the various components as follows: Cw = 4.1766 kJ/kgK; Cp = 2.0319 kJ/kgK; Cf = 2.0117 kJ/kgK; Cc = 1.5857 kJ/kgK; and 1.1289 for Ca. Thermal conductivity was determined using the parallel and perpendicular model[12] using equations (5) and (6) as follows:

Parallel model:



Perpendicular model:



where kw and ks are the thermal conductivities of the water and solids content of the fillet, respectively, and Vw and Vs are the volume fractions of the water and solids, respectively. Miles et al.[13] reported the thermal conductivities of various components as follows: kw (water) = 0.6 W/mK; kp (protein) = 0.2 W/mK; kf (fat) = 0.18 W/mK; ka (air) = 0.025 W/mK; kc (carbohydrate) = 0.245 W/mK, and ks (solids) = 0.26 W/mK.

The volume fraction of water was determined using equation (7) for water as follows:



whereas the volume fraction of solid content in the shrimp was determined using equation (8) as follows:



The thermal diffusivity (α) was determined using the following relation equation:



The latent heat (λ) for the shrimp was determined[12] using the following equation:




   Results Top


The results of proximate composition for the farmed shrimp used in the experiment are summarized in [Table 1]. Three replicates were used for analysis and the average values of proximate composition for L. vannamei variety of shrimp were obtained.
Table 1 Proximate composition of Litopenaeus vannamei

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Correlation matrix of proximate composition and the thermophysical properties of shrimp are presented [Table 3]. The table shows the dependence of thermophysical properties of shrimp with that of the proximate composition.
Table 3 Correlation matrix of proximate composition and the thermophysical properties of shrimp

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   Discussion Top


[Table 1] reveals that the values of proximate composition obtained are in agreement with the published data for L. vannamei variety of shrimp.[14]

The density of the shrimp is slightly higher when compared with water alone, indicating the influence of proximate composition [Table 2]. The value of the specific heat is in agreement with that of Miles et al.[13]
Table 2 summarizes the predicted values of the thermal and physical properties of farmed shrimp.

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Correlation analysis reveals that specific heat, thermal conductivity (perpendicular model), and latent heat have been positively correlated with protein content of shrimp, whereas thermal diffusivity and thermal conductivity (parallel model) have negative correlation with protein content of shrimp [Table 3]. Further, latent heat of shrimp has a weak positive correlation with protein content of shrimp and strong positive correlation with carbohydrate, fat, and water. Thermal conductivity (perpendicular model) has weak positive correlation with fat and water, and has strong positive correlation with protein and ash. Shrimp density has strong correlation with protein followed by ash. The thermal conductivity value for perpendicular model was higher than the parallel model. It reveals that heat may be transferred better across the fibers of the shrimp than along the fiber and is in reverse trend as observed in fish fillet.[10] The ash content inversely correlated with thermal diffusivity. This shows that the higher the ash content, heat diffusion would be less in shrimp meat.


   Conclusions Top


Shrimp is one of the most valuable sources of high grade protein among the seafood category. The shrimp is also one of the important resources of economic importance in the aquaculture. The knowledge of its engineering properties is essential to its processing and preservation to increase its value as food. This study is intended to predict the thermophysical properties of shrimp from the proximate composition of the shrimp meat. When specific heat, thermal conductivity, and thermal diffusivity are strongly influenced by protein content, latent heat is strongly influenced by water content in the shrimp meat.

The thermophysical data obtained in this study could be used as input in heat transfer calculations and to establish critical control points during the drying, freezing, and thermal processing of shrimp meat.

Acknowledgment

The authors thank the Tamil Nadu Dr J. Jayalalithaa Fisheries University, Nagapattinam, Tamil Nadu, India for the infrastructural support to carry out the research.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
   References Top

1.
Journal article on the Internet: Victor Suresh. How India became the world’s top shrimp producer. Global Aquaculture Advocate 2020. Available at https://www.aquaculturealliance.org/advocate/how-india-became-the-worlds-top-shrimp-producer/  Back to cited text no. 1
    
2.
Journal article on the internet. Global shrimp industry − the Indian dynamics. Televisory 2019. Available at https://www.televisory.com/blogs/-/blogs/global-shrimp-industry-the-indian-dynamics  Back to cited text no. 2
    
3.
Lewicki PP. Water as the determinant of food engineering properties: a review. J Food Eng 2004;61:483-95.  Back to cited text no. 3
    
4.
Latimer GW. Official Methods of Analysis of AOAC International. Gaithersburg, MD:AOAC International;2016.  Back to cited text no. 4
    
5.
Mariotti F, Tome D, Mirand PP. Converting nitrogen into protein—Beyond 6.25 and Jones’ factors. Crit Rev Food Sci 2008;48:177-84.  Back to cited text no. 5
    
6.
Lourenço SO, Barbarino E, De-Paula JC, Pereira LO, Lanfer MUM. Amino acid composition, protein content and calculation of nitrogen-to-protein conversion factors for 19 tropical seaweeds. Phycol Res 2002;50:233-41.  Back to cited text no. 6
    
7.
Mæhre HK, Dalheim L, Edvinsen GK, Elvevoll EO, Jensen IJ. Protein determination-method matters. Foods (Basel, Switzerland) 2018;7:5.  Back to cited text no. 7
    
8.
Bligh EG, Dyer WJ. A rapid method of total lipid extraction and purification. Can J Biochem Physiol 1959;37:911-17.  Back to cited text no. 8
    
9.
Folch J, Lees M, Sloane SGH. A simple method for the isolation and purification of total lipids from animal tissues. J Biol Chem 1957;226:497-509.  Back to cited text no. 9
    
10.
Lewis MJ. Physical Properties of Foods and Food Processing Systems. Chichester, UK:Ellis Horwood Publishers 1987.  Back to cited text no. 10
    
11.
Peleg M. Physical characteristics of food powders. In Peleg M, Barley EB, eds. Physical Properties of Foods. Westport, CT:AVI Publishers 1983.  Back to cited text no. 11
    
12.
Singh RP, Heldman DR. Introduction to Food Engineering. 4th ed. USA: Academic Press 2009.  Back to cited text no. 12
    
13.
Miles CA, Van BG, Veerkamp CH. Calculation of thermophysical properties of foods. In: Jowitt R, ed. Physical Properties of Foods. New York: Elsevier Applied Science Publishers 1987.  Back to cited text no. 13
    
14.
Shalini R, Abdul RN, Mohideen ABH, Selvaraju S. Biochemical changes of Litopenaeus vannamei and Fenneropenaeus indicus in the different stages of WSSV infection. J Coastal Life Med 2013;1:19-25.  Back to cited text no. 14
    



 
 
    Tables

  [Table 1], [Table 2], [Table 3]



 

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