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PRACTICAL TECHNOLOGIES FOR THE UTILIZATION OF AQUACULTURE PRODUCTS IN THE PHILIPPINES: STATUS AND PROSPECTS
 
 
Encarnacion Emilia S. Yap 
College of Fisheries and Ocean Sciences, 
University of the Philippines Visayas, Philippines
 
 
 
ABSTRACT
 
The paper discusses the present status and trends on the utilization of aquaculture products in the Philippines. Results of a recent survey on post harvest handling and processing activities in the Philippines indicate increasing emphasis on utilization of both traditional and high value aquaculture species. Activities related to value addition, waste utilization, raw material and product characterization, and mariculture are also prevalent in the country. In the same survey, research gaps are identified and these include the need to focus on exploration of possible bioactive substances from different aquaculture products and solid wastes from fish processing plants that could be used as potential neutraceuticals and functional food ingredients. Food safety related researches are also needed, including the identification of specific hazards that are associated with the production, post harvest handling and processing of aquaculture commodities. 
 
A recent attempt to develop sustainable technologies that can enhance productivity in the aquaculture sector through reduction of losses due to off-odors and off-flavors is also discussed.
 
 
Keywords: aquaculture products, Philippines, post harvest losses, off-flavor, off-odor
 
 
INTRODUCTION
 
The Philippines is one of the Asian countries that relies heavily on fish and fishery products as sources of dietary animal proteins. Being archipelagic in nature, this does not come as a surprise, more particularly in coastal areas where aquatic resources abound. However, due to the recent decline in fish production both from marine and freshwater sources, culture of different species was given much attention. In fact, aquaculture has been contributing significantly to the overall fisheries production in the Philippines lately, in terms of volume and value (BAS, 2013). 
 
Such focus on aquaculture commodities requires practical, sustainable post harvest technologies for their enhanced utilization. These technologies become even more important if the full potential of these commodities are to be targeted in order to increase their competiveness, both domestically and globally. 
 
Hence, this paper aims to look at the present status and trends on the utilization of aquaculture products in the Philippines. It focuses on the results of a recent survey on post harvest handling and processing activities in the Philippines and the utilization of both traditional and high value aquaculture species. Other post harvest activities such as value addition, waste utilization, raw material and product characterization, and mariculture are also discussed, as well the research gaps and areas of improvement that need attention in future activities. 
 
PHILIPPINE FISHERIES PRODUCTION
 
Total fisheries production in the Philippines gradually increased from ca. 3.62M metric tons in 2003 to ca. 5.16M metric tons in 2010 (BAS, 2013). The continuous reliance on, and the exploitation of, both the municipal and commercial fishing grounds led to the significant decrease in production from these two sub-sectors in the succeeding years (Fig. 1). Such decrease had been compensated by an increasing aquaculture production, although this seems not to be enough to prevent the decrease in total fisheries production in the country from 2011 until 2012 (Fig. 1). For a country with an increasing population and a demand of at least 35.22 kgs per capita supply of fish, it becomes important to look closely at aquaculture production and the optimum utilization of aquaculture commodities in order to meet the demand of its populace.
 
THE PHILIPPINE AQUACULTURE INDUSTRY
 
Aquaculture has been contributing significantly to the overall fisheries production in the country, in terms of volume and value, for the last ten (10) years. In 2010 alone, aquaculture production reached ca. 2.54M metric tons or ca. 49.34% of the total fisheries production in the Philippines, valued at ca. PhP 83 B or ca. 37.48% of the total value of production (BAS, 2013). The percent contribution of aquaculture even increased in the succeeding years to ca. 52.32% of the total production (see Fig. 1). 
 
However, a closer look at these figures would reveal that seaweeds contributed significantly to such increase in total aquaculture production (Fig. 2). In 2012 alone, ca. 1.75M metric tons of seaweeds were produced and these contributed to ca. 68.86% of the total aquaculture production of the country (BAS, 2013). Next to seaweeds are milkfish, tilapia, and tiger prawns as the main cultured species (Fig. 3). Interestingly, although the production figures of the other species are not as much as compared to these three main species, the potential of these species, including shellfishes (e.g. mussels and oysters), mudcrab, catfish and white shrimps, cannot be ignored  (Fig. 4). 
 
In terms of culture environments, seaweeds are most cultured in marine waters whereas majority of the supply of milkfish were from brackish water fishponds, pens, or cages, although its culture in marine pens and cages are gaining popularity lately. Tiger prawns are usually culture in brackish water fishponds wile tilapias are usually cultured mostly in brackish water and freshwater ponds, pens, and cages (BAS, 2013).
 
PRACTICAL TECHNOLOGIES FOR THE UTILIZATION OF AQUACULTURE PRODUCTS
 
Majority (ca. 70%) of the total fish production in the Philippines is generally consumed either in fresh or chilled forms, while the remaining amount (ca. 30%) is intended for processing into salted, dried, smoked, fermented, marinated, canned, or frozen products (see CNFDP, 2006). In most cases, people in the coastal communities in the country heavily rely on the more traditional methodologies such as salting, drying and fermentation, as a source of income (Yap et al. 2013). In terms of marketing, approximately 80% of the total fish production in the country is consumed locally, while the remaining 20% is generally exported in different forms as fresh/chilled, frozen, canned and value added products (CNFIDP, 2006). Among the aquaculture commodities in the country, majority of the traditional species (e.g. milkfish, tilapia and shellfishes) is either retailed in traditional landing facilities or sold to middlemen, or directly processed into traditional products. Only catches of high value species (e.g. tiger prawn, grouper, snapper, etc.) find their way to the more lucrative urban and export markets.
 
Results of a recent survey on post harvest handling and processing activities in the Philippines indicate increasing emphasis on utilization of both traditional and high value aquaculture species. The following discussion focuses on two (2) important aspects of post harvest activities, namely post harvest handling and processing of aquaculture commodities.
 
Post harvest handling: fresh fish and live food fish handling
 
Immediately after harvest, cultured species in the Philippines are usually iced in either aluminum or plastic tubs or styropore boxes. The use of such cold-shock treatment post harvest had been studied in the past either as a means to control biofouling and pest species on cultivated oysters (Cox et al. 2012) or as a quality preservation technique in big head carp (Panggat, 1987). Traditionally, most of these aquaculture produce, once iced, is either auctioned on site or transported to major and/or municipal fish ports for auctioning. Those who are engaged in on-site bidding are middlepersons and fish exporters, while bidding in fish ports is typically done by middlepersons, fish vendors in the local wet markets and small fish processors. 
 
The most common preservation method in landing sites is chilling, normally with the use of crushed ice, although other chilling media are also available in the Philippines (e.g. flaked ice, tube ice, refrigerated/chilled seawater, seawater ice and slushed ice). The choice of the medium used highly depends on their availability and affordability.
Transfer of live cultured fish to supply the institutional markets, both domestically and internationally, is usually done to aquaculture species such as grouper, snapper and freshwater prawns. Such technique requires much attention, for live fish generally command premium price in the market because it maintains the quality, freshness, and intrinsic flesh characteristics of the produce. In the Philippines, live fish are usually placed in large plastic bags with aerated water. The bags are then individually placed in boxes, the sides of which are lined with crushed ice. These boxes are then transported in airplanes to specific locations.
 
A new method to transport fish without water had been introduced in the Philippines (Comandate, B., 2005 – PUB WO/2005/039280). Accordingly, the process involves conditioning techniques and temperature manipulations. These include holding the fish overnight in filtered, circulated water at about 300C, without feeding, which is then followed by the transfer of the fish to another tank with water initially kept at 40C but later increased to 18 – 200C; after which, the fish is immersed for 4 minutes in a conditioning tank with an anti-stress solution and then the ‘stunned’ fish are arranged in cooled boxes lined with plastic bags. Finally, the bags are then filled with medical oxygen and sealed for transport.
 
Traditional and value-added aquaculture products 
 
Results of a recent survey on post harvest handling and processing activities in the Philippines indicate increasing emphasis onutilization of both traditional and high value aquaculture species. In terms of marketing of these products, traditional processed fish products (e.g., smoked, dried, salted, fermented and marinated, etc.) are sold in wet markets throughout the country. Some other products are sold in supermarkets, including canned/bottled fish, deboned milkfish, and specialty products (e.g., fish sausages, pasteurized fishpaste, crab fat, etc.).
 
Of all the aquaculture commodities produced, milkfish plays a very significant role, both in terms of volume and value. In 2012, milkfish contributed 15.21% in the total aquaculture production, valued at ca. PhP 34.8B or 37.76% of the total value of all aquaculture commodities in the country (BAS 2013). Although the export of milkfish has been increasing lately, majority of the total gross supply of milkfish in the country are consumed locally as fresh food fish while a good percentage is processed (Fig. 5). As shown in Table 1, milkfish are available in the domestic markets in different forms, including smoked, marinated, fermented, and fresh frozen products. Some value added products using milkfish are also available (Table 1, Fig. 6).
 
Tilapia ranked 3rd, in terms of volume and this is equivalent to ca. 10.25% of the total fish production in the country.  However, tiger prawn, which ranked 4th or equivalent to a mere ca. 1.90% of the total production, registered a value of ca. PhP 18.97B or an amount slightly higher than that of tilapia (ca. PhP 18.51B), most likely because tilapia are normally consumed locally (Fig. 7). The small differences between their values, however, have been observed lately, since the exportation of tiger prawns had been declining for the last 10 years and this has been accompanied by a corresponding increase in its domestic consumption (Fig. 8). Tilapia products include bottled, smoked, and filleted tilapia (Table 1 and Fig. 6), while tiger prawns are usually marketed as frozen blocks (Table 1).
 
Seaweeds has been consistently produced in significant amounts for the last 10 years, with a total production that amounted to 1.75M metric tons in 2012 (or ca. 68.86% of the total aquaculture production). However, this 2012 production figure was only valued at ca. PhP 9.78B, or only ca. 10.59% of the total production value. Not much seaweed products are available for the direct consumption of consumers (Table 1) since majority of these species are traded as raw materials for the extraction of the phycocolloid, carrageenan (see Canete and Montano 2002).
 
RESEARCHES ON UTILIZATION OF AQUACULTURE PRODUCTS
 
An inventory of the research activities related to fisheries post harvest was conducted to determine the research trend and needs (Yap 2006). A total of 216 researches done in a span of 30 years were analyzed from eleven (11) research and academic institutions in the Philippines.
 
Results of the survey show only ten (10) commodity groups were well-researched during the period (Fig. 9). These commodity groups include aquaculture species such as milkfish (18%), shrimps (13%), and seaweeds (12%). The remaining commodity groups, namely mussel/oyster, tilapia, cephalopods, crabs, and carp, are mostly aquaculture species that constitute the remaining 25% of the researches surveyed.
In terms of post harvest methodologies, most of the researches (36 out of the 216 researches or 17%) dealt with raw material characterization while 24 (or 11%) were on waste utilization. Other research topics included the use of different post harvest technologies, value addition, and marketing (Fig. 10).
 
In terms of research trend, it appears that more and more researches are focusing on the use of traditional processing technologies as unit operations in the production of value added products. Researches on non-traditional processing methodologies (i.e. mincing and surimi process technology), as well as waste utilization, exhibit a steady increase in number from 1975 until 2006. 
 
For example, several research efforts in the past have focused on fishery by-products and waste as potential sources of different products (e.g. Panggat and Shindo, 2003; Tejas and Yap 2003; Panggat and Rivas, 1997; Yap and Pascual, 1996; Ayon, 1994). However, research on the use of milkfish and milkfish processing wastes had been limited to development of value added consumer products using milkfish processing wastes (Panggat 2003), full grown milkfish (Mendoza 2003) and bait-size milkfish (Peralta, 2003), screening of while pond-cultured milkfish eyeballs, heads and livers for the presence of polyunsaturated fatty acids (Guirgen, 2000) and use of milkfish processing wastes in the production of fish fermented products (Mendoza and Taruc, 2003; Santos, et al. 1977). With regard to shrimps, attempts have been made in the past on the extraction of chitosan from shrimp processing waste (Finalla 2002; Quintos, 1996; Malicdem 1995; Nuqui et al. 1995), but these research initiatives have not been sustained. Researches on seaweeds have also been conducted in an attempt to develop new products other than the commercially important phycolloids (Mamaril, 1998; Montano et al. 1999).
 
One of our interesting researches recently is related to the development of sustainable technologies that can enhance productivity in the aquaculture sector through reduction of losses due to off-odors and off-flavors. The off-flavour compounds that cause “earthy” and “musty” organoleptic characteristic in some aquaculture species, more particularly milkfish and tilapia, have been a problem since they cause massive rejection even by the domestic consumers. These compounds include geosmin and 2-methylisoborneol (MIB), known metabolites from some algal and bacterial species. 
 
In our research, we tried to test the ability of food grade organic acids (acetic acid and citric acid) to suppress the production of these compounds. When the levels of these compounds were analysed by Solid Phase Microextraction (SPME) using Gas Chromatographic/Mass Spectroscopic analyses, results indicate that acidification treatments using varying concentrations of the acids significantly reduced the concentrations of the off-odour compounds. Treatments with 1.0% citric acid and 4.0% acetic acid significantlyreduced the concentration of geosmin to low concentrations (0.07±0.03 and 0.09±0.01 mg Kg-1 respectively) (Fig. 11), while the reduction of MIB to around 0.05±0.01 mg Kg-1 was achieved at a minimum concentration of 0.1% of either acids used (Fig. 12). Mass spectral analysis also showed that both geosmin and MIB were degraded to non-odourous products (Pahila and Yap 2013). Follow up studies on early detection and control of the production of these off odours are still ongoing.
 
CONCLUSION
 
Fisheries remain as a valuable industry in the Philippines. Although there have been recent decline in production from municipal and commercial fisheries sectors, aquaculture stays as the most promising production sector, for it is not only producing table fish, it also does not contribute to the exploitation of the wild stocks. Utilization of these aquaculture produce is on the rise and researches, both in the past and in the present, suggest the consistent focus on these commodities. Based on the inventory of these researches, gaps have been identified and these include the need to focus on the exploration of possible bioactive substances from different aquaculture products and solid wastes from fish processing plants that could be used as potential food ingredients and the functionality testing of these ingredients (Yap, 2010).  Food safety related researches are also needed, including the identification of specific hazards that are associated with the production, post harvest handling and processing of aquaculture commodities. Likewise, marketing studies must be conducted. 
 
REFERENCES
 
  • Ayon, P. 1994. Preparation of fish calcium concentrate from backbones of skipjack (Katsuwonus pelamis) and Indo-Pacific sailfish (Istiophorus platypterus). Undergraduate Thesis, College of Fisheries, University of the Philippines Visayas, Iloilo, Philippines.
  • Bureau of Agricultural Statistics. 2013. CountrySTAT Philippines. Department of Agriculture, Philippines. In: http://www.bas.gov.ph/
  • Canete, S. and N. E. Montano. 2002 Kappa-carrageenan gel as agent to sequester Paralytic Shellfish poison. Marine Biotechnology 4(6): 565-570.
  • Comandante, D. 2005. Patent on Waterless Transport of Live Fish, in http://patentscope.wipo.int/search/en/detail.jsf?docId=WO2005039280&recNum=1&maxRec=&office=&prevFilter=&sortOption=&queryString=&tab=PCT+Biblio
  • CNDIDP - Comprehensive Fisheries Industry Development Plan (2006-2020), 2006. Bureau of Fisheries and Aquatic Resources. Quezon City, Philippines.
  • Cox, B., P. Kosmeyer, W. O’Connor, M. Dove, and K. Johnstone. 2012. Oyster Over-catch: Cold Shock Treatment. Australian Seafood Cooperative Research Centre, South Australia.
  • Finalla, J. 2002. Extraction and characterization of chitosan from crab (Portunus pelagicus) shells. Undergraduate Thesis, College of Fisheries, University of the Philippines Visayas, Iloilo, Philippines.
  • Guirgen, R. 2000. Omega-3-fatty acids determination in eyeballs, heads and livers of pond cultured milkfish (Chanos chanos). Undergraduate Thesis, College of Fisheries, University of the Philippines Visayas, Iloilo, Philippines.
  • Malicdem, G. 1995. Extraction and storage stability of astaxanthin from shrimp (Penaeus monondon) waste. Undergraduate Thesis, School of Technology, University of the Philippines Visayas, Iloilo, Philippines.
  • Mamaril, E. 1998. Isolation, screening and characterization of nata-producing microorganisms from seaweed pulp (Gracilaria sp.). Graduate Thesis, College of Fisheries, University of the Philippines Visayas, Iloilo, Philippines.
  • Mendoza, L. and N. Taruc. 2003. Microbial fermentation of milkfish solid wastes. Terminal Report of Research on Utilization of Full Grown Milkfish, Philippine Council for Industry and Energy Research and Development, UP Visayas, Miagao, Iloilo, Philippines.
  • Montano, N. , R. Villanueva  and J. Romero. 1999. Chemical characteristics and gelling properties of agar from two Philippine Gracilaria (Gracilariales, Rhodophyta). Journal of Applied Phycology 11: 27-34.
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  • Pahila, J. and E. Yap. 2013. Reduction of off-flavour compounds (geosmin and 2-methyl-isoborneol) using different organic acids. Aquaculture, Aquarium, Conservation & Legislation International Journal of the Bioflux Society (AACL Bioflux), Vol. 6, Issue 6.
  • Panggat, E.B. 1987.  Cold shock in fish- its characteristics in bighead carp.  International Journal of Food Science and Technology.  1(22):20-25
  • Panggat, E. and J. Shindo. 2002. Omega-3-fatty acid from the by-products of yellow fin tuna intended for sashimi processing. Proceedings of International Commemorative Symposium – 70th Anniversary of the Japanese Society of Fisheries Science. Vol 68 Supplement I:1434-1436. 
  • Panggat, E. and L. Rivas. 1997. Omega-3-fatty acids from the heads and yeballs of big eye (Thunnus obesus) and yellowfin tuna (Thunnus albacares). FAO Fisheries Report No. 563. Quintos, J. 1996. Improvement of chitosan extraction from prawns (Penaeus monodon) heads. Undergraduate Thesis, College of Fisheries, University of the Philippines Visayas, Iloilo, Philippines.
  • Santos, L., F. Orejana, and M. Bautista. 1977. Utilization of by-products of milkfish processing: preparation of fish meal and silage. Fisheries Research Journal of the Philippines. 2(1):56-69.
  • Tejas, F. and E. Yap. 2003. Determination of ascorbic acid content of Gracilaria hetroclada, its processing wastes and product. Undergraduate Thesis, College of Fisheries, University of the Philippines Visayas, Iloilo, Philippines.
  • Yap, E. 2010. Potential Nutraceuticals and Functional Foods from Fishery By-Products in the Philippines: Status and Trends, A Country Report presented during the International Seminar on Improved Utilization of Fishery By-Products as Potential Neutraceuticals and Functional Foods, 26-29 October 2010, Kassetsart University, Bangkok, Thailand.
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Fig. 1. Total fisheries production in the Philippines from 2003 to 2012 (BAS, 2013).
 
 
 
 
 
Fig. 2. Total aquaculture production in the Philippines from 2003 to 2012 (BAS, 2013).
 
 
 
 
Fig. 3. Production of the top three (3) commercially important aquaculture species (excluding seaweeds) in the Philippines from 2003 to 2012 (BAS, 2013).
 
 
 
Fig. 4. Production of the other aquaculture species in the Philippines from 2003 to 2012 (BAS, 2013).
 
 
 
 
Fig. 5. Supply and utilization of milkfish in the Philippines from 2003 to 2011 (BAS, 2013).
 
 
 
 
Fig. 6. Examples of commercially available milkfish and tilapia products in the Philippines.
 
 
 
 
Fig. 7. Supply and utilization of tilapia in the Philippines from 2003 to 2011 (BAS, 2013).
 
 
 
 
 
Fig. 8. Supply and utilization of tiger prawns and shrimps in the Philippines from 2003 to 2011 (BAS, 2013).
 
 
 
 
Table 1. Summary of all available technologies for, and products from, commercially important aquaculture species in the Philippines.
 
 
 
 
Fig. 9. Researches conducted in the Philippines using different fisheries commodities.
Values expressed as percentages of the researches surveyed, n=216 (Yap, 2006).
 
 
 

Fig. 10. Researches conducted in the Philippines using different handling and processing methodologies . Values expressed as percentages of the researches surveyed, n=216 (Yap, 2006).

 

Fig. 11. Concentrations of geosmin, expressed as µg L-1(ppb) ± standard deviation, in different acidification treatments. Values under different letters are significantly different  (p ≤ 0.05) (Pahila and Yap, 2013).

 

Fig. 12. Concentrations of MIB, expressed as µg L-1 (ppb) ± standard deviation, in different acidification treatments. Values under different letters are significantly different (p ≤ 0.05) (Pahila and Yap, 2013).

 


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