Pineapple Wastes 4: Use of fruit wastes as animal feed
Published Date: 28th September 2020
Introduction
The pineapple fruit has always required some form of processing before consumption, whether for home consumption or small, and large-scale commercial processing. The processing involves essentially, removal of the crown if still present on the fruit, peeling the skin, and removal of the core. Commercially, the pineapple fruit is mainly produced as canned fruits that are consumed worldwide. The fruit can also be further processed into juices, concentrates, and jams, or as slices which are preserved by freezing. Pineapple fruit is again one of the primary ingredients used in producing fruit concentrates due to its neutral color, and flavor. All parts of the pineapple plant, including the fruit, can also serve as sources of bromelain, a proteolytic enzyme highly in demand in the pharmaceutical and food industries.
Throughout the pineapple fruit processing, and consumption chain, several tons of by-products are produced, which, in most cases, are discarded as waste. About 45 to 65 percent of the whole fruit is regarded as non-edible waste, including spent pulp, peels, crown with leaves, and pomace, and represents substantial residual biomass that will need to be disposed of. Furthermore, poor handling and storage can result in the rejection of a large proportion of whole fruits which again end up as wastes. However, this residual biomass is rich in soluble sugars, organic acids, and highly digestibility fibers, and therefore can serve as a substrate for the production of other value-added products. Thus, the wastes from pineapple processing industries have been used as substrates for bromelain, organic acids, ethanol, manure, and animal feeds production since they contain appreciable quantities of sugars, vitamins, and growth factors.
The exploitation of pineapple wastes by converting them into value-added products such as manure or animal feed is increasingly gaining attention as an innovative solution to their disposal challenges. Specifically, pineapple fruit wastes can serve as a cheap alternative feedstuff for different classes of livestock. The waste is however characterized by high moisture content, which reduces its keeping quality resulting in putrefaction, and spoilage within a few days. Therefore, the product requires some form of processing to increase its keeping quality, and reduce its potential to cause environmental hazards.
Physicochemical characteristics and uses of pineapple fruit waste
Pineapple fruit processing generates both solid, and liquid wastes containing high concentrations of biodegradable organic materials. The solid wastes in the form of peels and core have been estimated to account for 40 - 50 percent of the fresh fruit. They, therefore, form the major bio-waste generated during pineapple processing. The first step towards the optimization of the value of these wastes is to identify, and characterized them. The moisture content of the solid waste is about 87.5 percent and varies according to geographical location, and degree of ripeness of the fruit. The pineapple peel waste contains about 10 percent reduced, and 13 percent non-reducing sugars that encourage the growth of microorganisms. The sugars in the solid waste are mostly glucose (8.24 percent) and fructose (12.17 percent), and no sucrose because during the drying process at pH 4.0, the sucrose is converted to glucose and fructose. The liquid waste however contains sucrose, glucose, and fructose. Thus, the dominant sugars in the pineapple fruit wastes are sucrose, glucose, and fructose. Again, the waste contains some amounts of citric acid, which has been estimated at 2.18 g/l, against the 73.76 g/l estimated for total sugar.
The pineapple fruit wastes have substantial amounts of dietary fiber, especially insoluble dietary fiber, which are of high quality because of their physiological characteristics. The fruit waste contains about 4 percent ash, while potassium has the highest mineral concentration (3.0 percent), followed by magnesium (0.4 percent) and sodium (0.3 percent) among others. Table 1 shows the chemical composition of pineapple fruit solid waste.
The sugars present in the pineapple peel have been used as nutrients for microbes in fermentation processes. The peel is also a readily available substrate for methane, ethanol, and hydrogen generation. The fruit core also contains a lot of reducing, and non-reducing sugars, and has been used in the production of pineapple juice concentrates, alcoholic, and non-alcoholic beverages such as vinegar. Pineapple fruit waste fibers have been used in the development of low-calorie foods, and dietary fiber-enriched food products. Bromelain is perhaps the most valued constituent of the pineapple waste. It is predominantly present in the stem, with smaller quantities in the core, peel, crown, and extended stem. Bromelain has received a lot of research attention because of its proven anti-edematous, anti-inflammatory, anti-thrombotic, anti-cancer, fibrinolytic, and meat tenderizing activities. Pineapple fruit wastes are used as low-cost substrates for the production of lactic, citric, and ferulic acids through submerged, and solid-state fermentation. Vinegar and vanillin, a precursor of vanillic acid can also be produced from pineapple fruit wastes using a two‐stage fermentation process. These compounds are widely used in the food, pharmaceutical, and beverage industries for acidification, and enhancement of flavor.
The abundant fermentable sugars in pineapple fruit wastes serve as ready substrates for alcohol production, through the actions of organisms like Saccharomyces cerevisiae and Zymomonas mobilis, with or without the aid of enzymes like cellulase and hemicellulase enzymes. These organisms are capable of producing up to 8 percent ethanol from pineapple fruit wastes in 48 hours. Phenolic antioxidants content of pineapple fruit wastes has also been found to be high, with methanolic extraction yield, and total phenolic contents being 30.2 percent and 10 mg/g respectively from the pulp, seeds, and peels. The high content of organic matter in the pineapple waste has also been exploited through anaerobic digestion and composting to generate biofuels and manure. For example, pineapple peels are a promising feedstock for biogas generation, since they are rich in carbohydrates and proteins. Their biogas yields ranged from 0.41 - 0.67 m3/kg volatile solids, with a methane content of 41- 65 percent. Again, the sugars contained in the wastes have been utilized in the production of single-cell proteins like yeast, and Candida utilis for various industrial applications.
The pineapple fruit wastes also called bran, are being exploited as a feedstuff for different classes of animals. The wastes are however highly perishable and are therefore processed either by drying, ensiling, or pelleting to improve their keeping quality and nutritional values for extended storage. The nutritive value of pineapple fruit wastes varies with the ratios of the different by-products contained, the cultivar, stage of ripening, and the juice extraction technology employed. For example, the amount of nutrients in pineapple wastes decreases with the efficiency of the juice extraction. On a dry matter basis, the fresh pineapple waste has been shown to contain 4 – 8 percent crude protein, 60 – 72 percent neutral detergent fiber, 40 – 75 percent soluble sugars, pectin, and low amounts of minerals. There is therefore the need to add extra protein and mineral sources when formulating pineapple fruit wastes-based diets for animals.
Processing of pineapple fruit wastes into feedstuff
Preservation of the high moisture pineapple fruit wastes by anaerobic fermentation is a simple, method of improving the nutritional quality, and also extending the usefulness of the feedstuff over longer periods of time. However, feedstuffs preserved by anaerobic fermentation usually deteriorate once exposed to aerobic conditions, indicating the need to stabilize them through drying or other processes. Researchers at the University of Puerto Rico at Mayagüez, Puerto Rico, evaluated the fermentative characteristics, and aerobic stability of pineapple fruit wastes during 65 days’ anaerobic fermentation period and reported the final pH to be 3.21, while lactic acid was the main product associated with the fermentation. Crude protein content increased from 3.86 to 5.01 percent, while neutral detergent fiber, acid detergent fiber, and water-soluble carbohydrates increased from 433.7 – 45.75 percent, 21.89 – 27.21 percent, and 6.11 – 7.31 percent respectively. Thus, ensilage could be used as a viable method of preserving the high moisture pineapple fruit waste, as indicated by the chemical composition of fresh, and ensiled materials.
Utilization of fungal fermentation for nutrient enhancement of agro bio-wastes, due to their ability to degrade the lignin, cellulose, and hemicellulose polymers found in the substrates has been severally reported. For example, Aspergillus niger and Trichoderma viride have been successfully utilized in solid-state waste management, biomass energy conservation, and production of secondary metabolites in various agro-industrial wastes. Studies at the Mount Kenya University, Thika, Kenya, evaluated the nutrient enrichment of pineapple fruit waste using A. niger and T. viride by solid-state fermentation. Steam sterilized pineapple fruit wastes were inoculated with 15 ml of 2 percent fungal spore suspension of A. niger, and T. viride and incubated at ambient temperature for 48, 72, and 96 hours, and then dried for 72 hours at 60oC before proximate analysis. The result showed that the most significant crude protein enrichment was recorded at 72 hours of fermentation using A. niger (3.69 - 10.28 percent), and at 96 hours of fermentation using T. viride (3.69 – 9.04 percent), while both organisms reduced the crude fiber content from 10.80 to 2.49 and 7.59 percent respectively at the end of 96 hours of fermentation.
Ragi tape, a traditional Indonesian commercial product containing Candida parapsilosis, C. melinii, C. lactosa. C. solani, Hansenula subpelliculosa, Rhizopus oligosporus, Aspergillus f1avus, A. oryzae, and Hansenula malanga, was used to develop a procedure for converting pineapple waste into animal feed by researchers at the Sam Ratulangi University Manado, Indonesia. The substrate was mixed with 30 g ragi tape/kg, and incubated for three days at room temperature, and resulted in the increase of crude protein from 0.92 to 7.87 percent, crude fat from 0.82 to 1.53 percent, calcium from 0.58 to 12.73 percent, and gross energy from 2782 to 3830 Kcal/kg.
Composites of pineapple fruit waste and rice straw have also been compressed into animal feed blocks or pellets to extend the keeping quality of the pineapple waste. In a study at the Indian Center for Agricultural Research, Meghalaya, four ratios of pineapple waste, and rice straw viz., 0:100, 10:90, 20:80, and 30:70 were mixed with 10 percent molasses as a binding agent, compressed at different compression pressures of 13.78, 20.68 and 27.58 MPa to uniform square feed blocks of 8 x 8 cm. The bulk density, resiliency, hardness, and compression ratio values of the blocks ranged from 482.13 to 647.87 kg/m3, 23.79 to 29 percent, 66.28 to 106.34 N, and 8.56 to 11.17 respectively, with a compression pressure of 27.58 MPa in 30:70 ratios being the appropriate combination for a stable, denser, and resilient feed block.
Nutritive value of pineapple fruit waste for poultry
Pineapple fruit waste or bran has been fed to poultry either in its dried form or as a fermented product. Wet pineapple bran can be sun-dried within 3 days or artificially dried in an oven within 1 day. The inclusion of 15 percent pineapple bran in chicken diets was reported to depress feed conversion ratio and weight gains. This is probably because of the limiting effects of its high fiber, and low protein contents. This can, however, be improved by the action of beneficial cellulolytic microbes that reduces the fiber and increase the dry matter and crude protein contents during fermentation. Researchers at the Sam Ratulangi University Manado, Indonesia, evaluated the effects of pineapple waste meal fermented by “ragi tape”, a commercial product containing Candida parapsilosis, C. melinii, C. lactosa. C. solani, Hansenula subpelliculosa, Rhizopus oligosporus, Aspergillus f1avus, A. oryzae, and Hansenula malanga, on the performance, and carcass quality of broilers. The fermented pineapple waste meal was included in the diet at 0, 5, 10, 15, and 20 percent levels during 42 days feeding trial. The growth performance, carcass percentage, and abdominal fat percentage were significantly and positively affected by the dietary treatments, with the 20 percent treatment recording the highest income from the broiler production.
Researchers at the Visayas State University, Baybay City, Leyte, Philippines have also evaluated the anthelmintic efficacy of pineapple fruit peeling juice against common worms of semi-scavenging native chicken. The birds were treated with either levamisole, 1008, 504, or 255 mg/kg BW pineapple peel juice, and their fecal egg counts determined during the pre-treatment, 7th- and 14th-days post-treatment periods. Results showed significant worm egg reduction among the treated groups, with the 1008 mg/kg BW dosage rate being effective on the 7th day, and highly effective on the 14th-day post-treatment, whereas the 504 and 255 mg/kg BW were both effective on the 14th-day post-treatment. The worm eggs identified included those of Ascaridia galli, Heterakis gallinarum, and Raillitina spp., indicating that pineapple fruit peeling juice can serve as an alternative anthelmintic in semi-scavenging native chicken.
Nutritive value of pineapple fruit waste for pigs
Early Hawaiian reports have shown that pineapple bran can be used advantageously as a feed for fattening pigs. In one of these reports, 50 percent pineapple bran-mixture inclusion in fattening pig diet resulted in an average daily gain of 0.97 pounds during a period averaging 81 days at a feed cost of $0.101 per pound of gain. Researchers at the Imo State Polytechnic, Umuagwo, Ohaji, Owerri, Nigeria, investigated the growth performance of weaner pigs fed 0, 5, 10, 15 percent dietary inclusion levels of pineapple wine sediment meal as a replacement for maize during 35 days’ trial. The result showed that the pineapple wine sediment meal could replace maize partially up to 10 percent dietary level for optimum performance of weaner pigs and that at higher levels of inclusion, growth rate, and feed conversion ratio were negatively affected.
Another study at the Dankook University, Choongnam, Republic of Korea, evaluated the effect of bromelain supplementation on growth performance, nutrient digestibility, blood profiles, fecal microbial shedding, fecal score, and fecal noxious gas emission on weanling pigs. The pigs were fed diets containing 0.05, 0.10, and 0.20 percent bromelain for 42 days. The average daily gains were 612, 616, and 637 respectively, compared to the 583 g recorded with the control diet that was not supplemented with bromelain. Overall, pigs fed a 0.10 percent supplemented diet recorded a higher average daily gain and average daily feed intake than the rest. Faecal E. coli counts and ammonia gas emission also decreased especially in the 0.05 - 0.10 percent bromelain treated pigs, thus highlighting the benefits of bromelain supplementation in pig diets.
Nutritive value of pineapple fruit waste for ruminants
Researchers at the Federal University of Agriculture, Abeokuta, Nigeria, fed dried pineapple waste meal as a supplement (25, 50, and 100 percent levels) in the normal grazing diets of crossbred calves, and observed that the highest nutrient intake occurred at 100 percent level of inclusion. The dry matter and crude protein digestibility increased significantly from the value at 25 percent, to 100 level of inclusion, and were reflected by the live weight gain of the calves which changed from 400 g for the 25 percent levels of inclusion to 800 g per day for the 100 percent level of inclusion. The study, therefore, concluded that dry pineapple waste meal can support the superior growth performance of calves. Indian studies in which a combination of four parts pineapple leafy crown, and one part peels/pomace (65–70 percent moisture content) was ensiled for 15 days, and fed to sheep, and cows at 62 percent inclusion level, did not report any deleterious effect on growth performance of sheep but reported improvements in average daily milk yield by 3.0 liters per cow.
Researchers at the Ladoke Akintola University of Technology, Ogbomoso, Nigeria have also evaluated the feeding value of 1:1, 1:1.5, 1:2, 1:2.5, 1:3 blends of wheat offal-carried pineapple waste (WO: PW) and brewers’ dried grains-carried pineapple waste (BDG: PW), with Madara goats. The blends were dried to a moisture content of 10.95 - 14.72 percent and offered free choice to the goats. Their findings showed that in each case, the 1:2 ratios (9.15 and 20.75 percent crude protein for WO: PW and BDG: PW respectively) was the optimum blend readily accepted by the goats, and are therefore recommended for feeding small ruminants.
Conclusion
Pineapple fruit processing and consumption generates large quantities of by-products, which, in most cases are discarded as wastes. These wastes can be converted into value-added products such as manure, animal feed, bioethanol, biofuel, and other useful substances. The high moisture and fiber contents of pineapple fruit waste lends it to quick spoilage and therefore needs to be processed in order to improve its keeping quality. Processed pineapple fruit wastes have been successfully fed to ruminants, pigs, and poultry, with good performance results.
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