Simple and quick method for recycling pineapple waste into animal feed

O A Makinde, S M Odeyinka and S K Ayandiran

Department of Animal Sciences, Obafemi Awolowo University, Ile-Ife, Osun State, 220005, Nigeria
olukayodemakinde@yahoo.com
olukayodemakinde@oauife.edu.ng

Abstract

Pineapple waste (PW) is a by-product from pineapple processing, mostly dumped and pollutes the environment. Therefore, a study was conducted to develop a simple procedure for converting pineapple waste into animal feed using wheat offal (WO) as an absorbent. Increasing quantities of fresh PW were mixed with WO (w/w) at the following ratios (WO:PW), 1:1, 1:1.5, 1:2, 1:2.5, 1:3, and 1:3.5 and subsequently sun-dried for 4 h. Samples were analyzed for moisture content after 4 h and then proximate composition.

The results showed that 1:1, 1:1.5 and 1:2 (WO:PW) ratios dried to ≤ 10 - 12% moisture content in 4 h. Crude protein and crude fiber components ranged from  15 to 16 and 7.5 to 10%, respectively. The 1:2 (WO:PW) ratio was considered as the optimum combination for quickly recycling PW to animal feed using keeping quality and nutrient contents as criteria.

A simple and quick conversion procedure was developed for pineapple waste using wheat offal and absorbent. The product showed potential for use as animal feed ingredient.

Key words: Absorbent, waste conversion, wheat offal

Introduction

Globally, agricultural and food-processing industries have to contend with the problem of waste management due to huge amounts of by-products generated. The problem is more severe in developing countries because of undeveloped or non-existent processing or conversion of such by-products into useful products (Odeyinka et al 2003). As a result, there are serious environmental pollution and waste of potential feed resources.

Difficulty in the conversion of high-moisture by-products arises from high cost of drying equipment and lack of simple and appropriate alternatives (Makinde and Sonaiya 2010). One of such agro-industrial by-products is pineapple waste (PW) from pineapple processing, mostly dumped and pollutes the environment. Pineapple waste occurs as pineapple peels and core, making about 40-50% of the fresh fruit (Buckle 1989) and contains mainly sucrose, fructose, glucose and other nutrients (Krueger et al 1992). FAO (2004) ranked Nigeria among the leading pineapple producing countries with about 800, 000 metric tonnes since 2001, there fore, efforts at finding better use for the PW generated from such huge quantities may be important in terms of environmental pollution and waste of potential animal feed resource.  

Such efforts towards preventing and remedying pollution from PW by previous investigators involved sun drying and incorporation in animal diets with satisfactory results. Lamidi et al (2008) found that broiler chickens could tolerate up to 10% PW in their diets without any deleterious effect. Olosunde (2010) reported that WAD sheep could tolerate up to 45% PW but 30% PW was superior even against 0% PW when substituted for corn bran. Babatunde (1988) classified PW as an alternative feed ingredient to conventional wheat offal. These indicate potential for use as animal feed.

Nevertheless, the long drying period in these studies (about 5 or 7-14 days) may be exigent for an efficient and sustainable conversion of PW to animal feed. Therefore, the development of a quicker conversion procedure will be important in contributing to alternative animal feed, sustainability of animal protein supply, augmentation of rural income in pineapple growing areas and reduction in environmental pollution.

Makinde and Sonaiya (2007, 2010) developed a quick method (maximum of 4-h drying period) to convert into animal feed such wet by-products as pineapple waste (specifically underutilized abattoir by-products comprising blood and rumen contents) using vegetable carriers (wheat offal, dewatered rumen contents, maize offal and brewers’ dried grains) as absorbents. The studies showed that wheat offal (WO) had the highest absorbency compared to maize offal, brewers’ dried grains and dewatered rumen content. The procedure could be amenable to use in the quick conversion of PW into animal feed using WO.  There is lack of information on a procedure for converting PW into animal feed using WO. Therefore, the objective of this study was to develop a simple procedure for converting pineapple waste into animal feed using wheat offal as an absorbent.

Materials and methods

Processing of pineapple waste and wheat offal blend

The experiment was carried out at the Department of Animal Sciences, Faculty of Agriculture, Obafemi Awolowo University, Ile-Ife, Nigeria. Wheat offal was from Eagle Flourmills, Ibadan, Nigeria. Fresh wet pineapple waste (skins, peelings and the pulp peelings) was collected in polyethylene woven sacks from the Lafia Canning Factory of Fumman Agricultural Products Nigeria Ltd, Moor Plantation, Ibadan, Nigeria.

Pineapple waste was thoroughly hand-mixed with wheat offal in increasing concentration. Six sets of the PW and WO mixture were evaluated based on capacity to dry to ≤ 10 - 12% moisture content in 4 h (Makinde and Sonaiya 2007, 2010). The decision criterion was to select the mix with the highest PW content that dried to ≤ 10 - 12% moisture content in 4 h. The following shows the combinations (w/w) tried:

(a) WO mixed with PW (1:1)

(b) WO mixed with PW (1:1.5)

(c) WO mixed with PW (1:2)

(d) WO mixed with PW (1:2.5)

(e) WO mixed with PW (1:3)

(f) WO mixed with PW (1:3.5)   

The mixtures were sun-dried by spreading thinly on black polythene sheets (0.7 mm thickness) in two replicates each on the concrete roof (20.5 m high) of the Faculty of Agriculture, Obafemi Awolowo University, Ile-Ife, Nigeria. The surface area (m2) covered by the blends during drying was measured to enable estimation of sun drying rates (as kg/m2/h). Wetness of the blends was estimated as the difference between the initial weight and the final weight (after drying) of the mixture. Drying started at about 12.00 h and the mixtures turned once after 30 min of the first hour into drying. This involved rubbing handfuls together and spreading again; after drying ended, the mixtures were blended with a plate (burr) mill. Storage of dried and cooled blends was in high-density polythene bags and then in a freezer for subsequent use.

Chemical analysis

Proximate composition was determined according to the methods of AOAC (2000). Dry matter of the blends were determined by drying at 105oC for 24 h, cooled in desiccators and weighed again until constant weight. Ash was determined after ignition in a Gallenkamp muffle furnace at 600oC for 3 h. Crude protein (CP) was estimated as Kjeldahl N × 6.25 using a Kjeltec 2300 Analyser Unit (FOSS Analytical AB, Sweden) after samples were digested in concentrated sulfuric acid. Ether extract was determined by using petroleum ether (bp 40 –60o C) extraction in a Soxhlet extractor (Phillip Harris, Birmingham, England).

Data analysis

The differences in sun drying rates, moisture content and wetness between the six blends were analyzed with the 2-way analysis of variance using the General Linear Models procedure of SAS (2000). The data was treated as a completely randomized block design with vegetable carrier as the main treatment effect and replicates as the block. The replicate was considered as blocks in order to increase the sensitivity of the experiment by reducing the residual error. The model used was:

Y ijk = μ + Bi + Rj + ε ijk

Where: Y ijk = drying rate, moisture content and wetness, μ = overall mean, Bi = blend effect,

Rj = replicate effect and ε ijk = residual error.

Differences between the blends were resolved by Duncan’s multiple range test of the SAS (2000) statistical package. Statistical significance was established when probability was less than 5% level of significance.

Results and discussion

Table 1 shows the drying characteristics of different blends of pineapple waste (PW) and wheat offal (WO) after 4 h sun drying. Sun drying of PW under the conditions of this study was significantly quicker than reported in previous studies by Lamidi (2008) and Olosunde (2010) (4 h vs. 5 or 7-14 days).  This result underscores the effectiveness of WO as an absorbent reported by Makinde and Sonaiya (2007, 2010). Mixing WO to PW broke PW into smaller units thereby increasing surface area for drying, which shortened drying time significantly. Sonaiya (1988) and Rozis, (1997) reported shorter drying times with increased air to product surface exchange area.

 

The moisture contents as well as wetness of the blends were significantly different (p < 0.05). Expectedly, moisture contents as well as wetness of the blends increased as the concentration of the PW increased because WO (dry material and absorbent) was constant as the PW (wet material) increased. The decrease in % moisture loss as the content of PW increased also reinforces this observation. Blends with PW ≥ 2.5 units were significantly wetter (p < 0.05) than PW ≤ 2.0 units. Since the decision criterion was to select the mix with the highest PW content that dried to ≤ 10 - 12% moisture content in 4 h, the blend ratio 1:2 (WO:PW) seems as the optimum combination for WO to effectively dry PW because moisture content > 12% is not desirable pertaining to good keeping quality (Rozis 1997). The wettest blend (1:3.5, WO:PW) had the highest (p < 0.05) drying rate (kg/m²/h)  because it had the heaviest material per unit area but did not dry to ≤ 10 - 12% moisture content in 4 h. Despite the blend ratio 1:2 (WO: PW) was not significantly different (p > 0.05) from 1:1.5 (WO: PW), it would be more desirable for use as feed because it converts more PW into feed and therefore, more efficient in reducing the nuisance from the waste. It could therefore be stored for dry season supplementation of low quality forage for ruminants. Nevertheless, the blends with PW ≥ 2.5 units, significantly wetter and probably with lower keeping quality, present greater opportunity for converting PW into useful product if used as soon as produced.

   

Table 2 shows the proximate composition of different blends of pineapple waste and wheat offal. The blend ratio 1:2 (WO:PW) compares favorably to the other combinations regarding potential feeding value. None of the blends had ≥ 18% CF or 20% CP, and cannot be classified as forages, roughages, or protein supplements but as energy supplements (Jurgens 1978; Singh and Panda 1988) or fillers (Babatunde, 1988).  According to Jurgens (1978), feeds that contain averagely more than 18% crude fiber (CF) on a dry matter basis are forages and roughages. Those that contain 20% or more of crude protein (CP) are protein supplements, while those with less than 20% CP are energy feeds. However, the CP contents obtained are three times greater than values obtained for PW by Abdullah and Mat (2008) and Olosunde (2010) but 5% short as protein supplements. This suggests potential for non-ruminant and ruminant feeding. For example, the CP content probably shows adequacy for sheep feeding when compared with CP requirement for sheep by NRC (1985) for maintenance (9%), flushing (8%), gestation (9-11%), lactation (13-15%) and finishing (12-14%).  In addition, Lamidi et al (2008) fed broiler chickens with inclusion of PW up to 10% in their diets probably indicating opportunity for higher inclusion rates since the blends are a combination of WO and PW, and probably more suitable for pigs because of their higher capacity for fiber utilization. These results indicate the potential of the combination of WO with PW as animal feed, a disposal route for PW in reducing environmental pollution, and addition to alternative feed sources.