Department of Marine Sciences, University of Puerto Rico, PO Box 5000, Mayaguez, PR ; INTRODUCTION

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1 PRODUCING A VIABLE SOYBEAN REPLACEMENT FOR DIETS OF FISH AND SHRIMP BY CENTRIFUGATION AND DRYING OF THE CONCENTRATE OF THE ANAEROBIC EFFLUENT SOLIDS FROM A RUM PRODUCTION FACILITY. J.M. Kubaryk 1, L.M. Szendrey 2, and A. Sanjuan-Marmolejo 1 1 Department of Marine Sciences, University of Puerto Rico, PO Box 5000, Mayaguez, PR ; 2 Bacardi Corporation, Call Box 70715, San Juan, PR SUMMARY The foundation stone of a strategy for building an efficient, cost effective and environmentally sound food system is to work toward converting suitable wastes into usable feed components with optimal efficiency. The accelerating rate that change is taking place removes the luxury of mistakes and places a premium on not reinventing the wheel. Anaerobic biological conversion of rum distillery wastes using a downflow filter process to produce methane was developed, tested and patented in 1981 by the Bacardi Corporation. Recently a novel treatment, employing centrifugation and temperature manipulation, was developed to convert the post-methane extracted distillery waste into a dry feed ingredient, BDS - Bacardi Dried Solids, that was tested as a replacement for soybean meal in the diets of a freshwater fish and a salt water shrimp. It was found that BDS can be included in diets without any safety considerations and that its replacement value was not affected by the various centrifugation rates and drying temperatures combinations used in its production for the studies reported here. For tilapias receiving 30% crude protein diets with BDS substituting for 80% of soybean meal growth and sensory characteristics were similar (P>.05), greater in some of the systems, than the tilapias receiving the non-bds substituted diet. Penaeus vannamei receiving 30 and 41% crude protein diets with BDS substituting for 60% of the soybean meal had similar (P>.05) growth and sensory characteristics than those shrimp receiving the non-bds substituted diets. The world will add some 850 million consumers between now and The development of the technologies, which can be employed by the food sector for using waste conversion to replace a traditional feed ingredient, will be cost effective as they relate to similar conversions and aid in meeting global food and beverage demands, which are primarily driven by increasing population growth and per capita income. Key words:soybean replacement, fish, shrimp INTRODUCTION In 1996 commodity prices shattered record highs, as poor harvests during the past few years forced prices upward. In addition, considering that the world will add some 850 million consumers between now and 2005 coupled with the expectation that the growth in the world s economy, which has increased some $4 trillion U.S. dollars between 1985 and 1995, will most likely continue, albeit at a less rapid pace, it appears that one can expect long-term upward pressure on commodity prices, even after harvests recover (Demetrakakes 1996, Brown et al 1995, Johnson 1996). One of the obvious ways to respond to this scenario without having producers swallowing price increases or consumers facing raising prices, is to use ingredients that have the long-term prospect of being price stable. This increasing, more affluent world population will increase demand for a wide range food and beverage products, which will also increase waste generation as these products are processed. If this increase in waste generation could be converted, efficiently and cost effectively, into a usable feed component it would provide the industry with a win-win solution as it tries to meet growing demands for a product while building an environmentally sound, secure global food system. It was reported that the Bacardi Corporation Anaerobic System was an efficient and versatile method for significantly reducing the organic discharge from its molasses-based distillery, as well as

2 supplying a significant portion of the energy required for their distillation process (Szendrey 1984). Recently a centrifugation and drying processes were incorporated to convert the effluent from the anaerobic filter into dried commodities that were approximately 33% crude protein, making them intermediate protein sources with a nutrient profile similar to corn distillers grains and brewers gain. Prior to developing the fully commercial process the anaerobically digested rum distillery waste was processed sun dried at 50 o C for two days. This product was tested and found that it could replace 80% of the soybean meal in tilapia diets that contained 30% dietary protein with no significant (P>.05) effect on growth (Sanjuan-Marmolejo 1996). He further demonstrated that at this replacement level the digestible energy value was nearly identical (3.27 Kcal/g for the BDS diet versus 3.22 Kcal/g for the control) to the zero replacement soybean meal diet. Based on these results a process was developed that would be able to convert the 30,000 to 40,000 kg of organic wastes that an anaerobic digestion process would produce daily from a commercial distillery operation into a usable feed ingredient. The purpose of the study that will be reported here was to determine if different centrifugation and drying procedures would have an effect of the products ability to replace soybean meal in the diets of Tilapia. MATERIALS and METHODS At the start of the study six fish, each averaging 11 g in total body weight, were stocked in each of twenty-two 60-l glass aquaria. Water flow from a storage tank was maintained at a rate of 1 ml/s, aeration was provided, and illumination supplied by fluorescent ceiling lights gave a 12:12 day light:dark cycle. The diets were fed once a day at 5% of body rate, six days a week for a period on seven weeks. After a 30 minute feeding period, 16:00 h, uneaten feed was siphoned out of each aquarium, filtered, dried and weighed. Fecal material was also siphoned out of each aquarium two hours after the feeding period, filtered, dried and weighed. Weight gained was monitored on the seventh day of each week, with the feeding rate being adjusted accordingly. The comparative slaughter technique of measuring changes in body composition was used to determine composition of gain following AOAC procedures (1984). The rationale for selecting a soybean meal and not a fish meal substitution is based on the fact that Puerto Rico has the largest tuna canning operations in the United States and exports fish meal for feed production, while it needs to import soybean meal. The feeds used in this study are presented in Table 1. All feeds were prepared by first dry mixing all the individual ingredients corresponding to that treatment ration, then adding water as the ingredients were further mixed until the desired consistency was obtained, prior to producing the pellets by extrusion using a model 7CA22 ButcherBoy. Pellets were allowed to dry prior to placing in storage bags and placed in a freezer at - 20 o C until needed. The granular BDS was produced by solar drying while the remaining other 9 BDS flakes were produced by steam drying. Table 1. Composition of feeds. Ingredient Percent of Feed Fish meal Corn Soybean 25 5 Wheat 7 7 Alfalfa 10 2 BDS Premixes For this study each diet was prepared using a different form of BDS based on RPM and Bar of the process. RESULTS and DISCUSSION

3 From the results presented in Tables 2 and 3, Figures 1 and 2, and coupled with the fact that no mortalities occurred during the study, it should be obvious that BDS does not have any toxic effects on tilapia. Changes in the drying pressure, denoted in tables and figures as Bar, did not yield any definite trends in weight, protein, or lipid gains, nor in protein efficiency ratios. However, at the lower Bar levels the 2RPM commodities resulted in slightly higher, but non-significant (P>.05) weight gains and conversion efficiencies than their 3RPM counterparts, while at the higher Bar levels the 3RPM commodities had similiar or greater gains than their 2RPM counterparts. These results probably indicate that the centrifugation rates used to produce the BDS have a minor role in determining the growth promoting ability of BDS. This hypothesis is supported by the facts that all of the flake treatments yielded significantly (P<.05) lower weight gains than the granule BDS treatment, which was produced by a 2RPM process, and there is a steady decline of approximately 2 grams for each increase in Bar, declining from a high of 70.56, 68.65, to a low for the 2, 3, 4, and 5 Bar treatments, respectively. These results could mean that the drying pressure used in the process has a greater influence on the replacement value of BDS for soybean meal than does the centrifugation rate. However, when a pond test was conducted with the sundried and 2RPM1Bar commodities formulated to be identical to the control and 2RPM1Bar feeds as presented in table 1, the feed produced from the sundried BDS developed mold after two months at ambient tropical temperatures, while the other two feeds did not. Since the average final body weights for the pond test were 356 and 364 for the BDS and non-bds fed fish, respectively (Kubaryk et al 1996), and cage tilapia receiving the same BDS replacement or control feeds had an greater average final weight (471.7 g versus g) their non-bds fed counterparts (Sanjuan-Marmolejo 1996), it appears that the temperature parameter used to produce BDS may have an effect on utilization under laboratory conditions, but at the commercial production level it is inconsequential since it is predisposed to mold growth. The 0% BDS feed was consumed in significantly (P<.05) greater quantities than all the flake diets but the difference between it and the granule BDS feed was not significantly different (P>.05). In addition, the granule diet was consumed in greater quantities than all the flake diets but this difference was significant (P<.05) only for the 2RPM5Bar and the 3RPM2Bar diets. Since the fish readily consumed all diets in this study, and it has been reported that tilapia will readily consume BDS as its only nutrient source for a month without developing swimming or behavioral abnormalities (Kubaryk et al 1996), it seems that BDS has no negative effect on palatability. The difference in consumption of the flakes and granular BDS feeds may be an artifact of the production method used in this study to produce the feeds. The flake BDS commodities required less water to get the desired consistency prior to pelleting than did the granular and control, perhaps slightly changing the textural properties. This assumption may be supported by the observation that the fish rapidly swallowed the control and granular feeds but were often seen swallowing, spitting out and reswallowing the flake feeds. This feeding behavior has been reported to be quite common for tilapia (Lim 1989). However, since consumption and conversion ratios of the flake BDS diets in the cage and pond studies (Sanjuan-Marmolejo 1996, Kubaryk et al 1996) were similiar to the control these results confirm that tilapia will readily consume diets that have BDS incorporated into them but the type of BDS used may have an effect on consumption when produced under laboratory production systems but in feed mills using dry processing methods this possibility can be ignored. These results have demonstrated that the centrifugation and drying processes that were used produced a suitable, safe dietary ingredient for tilapia. Since all the flake commodities yielded similar performance characteristics it appears that BDS s nutritive value for tilapia is not effected by this process. In addition, BDS can replace 60% of the soybean meal in the diets of the salt water shrimp, Peneaus vannamei without effecting growth rate and body composition (Kubaryk et al 1996). Since BDS is readily consumed and utilized by tilapia and shrimp its possible use in the aquaculture industry will probably be ultimately determined by its price relative to other protein sources. As such, future work should focus on processing parameters that will produce the commodity at the most cost effective method possible. One recent step that has been added to the process since this and the other studies (Sanjuan-Marmolejo 1996, Kubaryk et al 1996) were conducted has been that a decanter unit has been

4 added that now allows for the production of a commodity that has a protein content of 44.4%, a third greater than the original tested 33.3%, which may make it more attractive as it can now be classified as a high protein source. REFERENCES AOAC Official Methods Of Analysis of the Association of Official Analytical Chemists. Va pp. Arlington, Brown, L.R., Flavin, C. and Starke, L State of The World Worldwatch Institute, W.W. Norton & Company, New York. Demetrakakes, P Growing pains. Food Processing, 57 (8): Johnson, R Building of open food system should be primary goal. Feedstuffs, 68(38):8. Kubaryk, J.M., Sanjuan, A., and Szendrey, L.M Replacement value of Bacardi dried solids for soybean meal in diets for tilapia and the saltwater shrimp, Penaeus vannamei. VII. International Symposium on Nutrition and Feeding of Fish, College Station, Texas, USA, August 11-15, Lim, C Practical feeding - Tilapias. In: Lovell, T.R. (Ed.). pp Nutrition and Feeding of Fish. Van Nostrand Reinhold Publishing, New York, USA. Sanjuan-Marmolejo, A.E Efectos de la Sustitucion de la harine de Soya por Subproductos de la Distilacion del ron en dietas aplicadas a Tilapia (Oreochromis niloticus) y el Hibrido rojo O. mossambicus x O. niloticus. Tesis de Maestría. Universidad de Puerto Rico. RUM. 64 pp. Szendrey, L.M Anaerobic treatment of fermentation wastewaters. Environmental Progress, 3(4): Table 2. Performance of red tilapia receiving different forms

5 of BDS at 20% inclusion levels. Values are the average of two replicates stocked with six fish each. 1 Weight gain Food consumption Food conversion Ingredient (g) (g) (intake gain) Flakes 2RPM1Bar b bc 2.00 abc 2RPM2Bar b bc 1.92 abc 2RPM3Bar b bc 1.92 abc 2RPM4Bar b bc 2.12 a 2RPM5Bar b c 2.37 a Ave. 2RPM RPM2Bar b c 2.14 a 3RPM3Bar b bc 2.39 a 3RPM4Bar b bc 2.16 a 3RPM5Bar b bc 2.04 ab Ave. 3RPM Granule 2RPM a ab 1.59 bc Control 0% BDS a a 1.54 c 1 Values in the same column followed by the same letters are not significantly different (P>0.05). Table 3. Composition of gain of red tilapia receiving different forms of BDS at 20% inclusion levels. Values are the average of two replicates stocked with six fish each. 1

6 Protein gain Lipid gain Protein Efficiency ratio Ingredient (g) (g) Flakes 2RPM1Bar b b 1.65 b 2RPM2Bar b b 1.70 b 2RPM3Bar b b 1.70 b 2RPM4Bar b b 1.62 b 2RPM5Bar b b 1.48 b Ave. 2RPM RPM2Bar b b 1.56 b 3RPM3Bar b b 1.37 b 3RPM4Bar b b 1.54 b 3RPM5Bar b b 1.69 b Ave. 3RPM Granule 2RPM a a 2.06 a Control 0% BDS a a 2.15 a 1 Values in the same column followed by the same letters are not significantly different (P>0.05).