Evaluation of date-feed ingredients mixes
Ibrahim E.H. Belal
a,*, Mohammed S. Al-Jasser
b,
I.A. Mustafa
b, Mohammed N. Al-Dosari
caDepartment of Aquatic Wealth Development, College of Agricultural and Food Sciences,
King Faisal University, P.O. Box 420, Al-Hassa 31982, Saudi Arabia
bDepartment of Food Science and Technology, College of Agricultural and Food Sciences,
King Faisal University, P.O. Box 420, Al-Hassa 31982, Saudi Arabia
cDepartment of Animal Science, College of Agricultural and Food Sciences, King Faisal University,
P.O. Box 420, Al-Hassa 31982, Saudi Arabia
Received 3 June 1997; received in revised form 17 March 1998; accepted 15 June 1999
Abstract
Pitted dates (dates after pits removal) were mixed separately in a semi-liquid form with two feeds (yellow maize and wheat bran) then dried and ground. Each ingredient was mixed with the dates at 11 ratios (50 : 50, 55 : 45, 60 : 40, 65 : 35, 70 : 30, 75 : 25, 80 : 20, 85 : 15, 90 : 10, 95 : 5 and 100 : 00). All mixes were kept at room temperature (2428C) for three months. Then, chemical (proximate analysis), physical (pasting time and temperature, and maximum viscosity) and microbial (number of fungi per gramme) analysis were performed. The quality of each ingredient was found to improve with increasing level of pitted dates in terms of keeping quality and binding ability. In addition, proximate composition (crude protein, crude fat and total ash) reflected the proportion of each ingredient (yellow maize or wheat bran), their composition and the mixing level. Finally, the number of fungi per gramme was reduced as the level of dates was increased.#1999 Elsevier Science B.V. All rights reserved.
Keywords: Dates; Yellow maize; Wheat bran; Feed mills
1. Introduction
Dates grow in many developing countries where the supply of animal feed is very limited. Presently, Saudi Arabia is the largest date producing country in the world (0.5 Mt
81 (1999) 291±298
*Corresponding author. Tel.: +9663-5800000; fax: +9663-5801778
E-mail address: [email protected] (I.E.H. Belal)
per year). About 20% of the total production is unsuitable for human consumption and wasted (wasted dates are defined as one-year-old dates and/or fresh dates that are infested with insects1). Presently, wasted dates are being fed without any processing to camels, cows or sheep in variable amounts during the fall season. No scientific evaluation of wasted dates has been made under these conditions.
Dates have been used as a substitute for more expensive carbohydrate sources. Additionally, dates play a similar role in animal feeding to that of molasses as a binder for the pelleting process (Belal and Al-Jasser, 1997). Dates and molasses have some similarities and some differences in terms of their chemical composition (Sawaya et al., 1983; Ensmiger and Olentine, 1978). Both contain simple carbohydrates, but dates contain mainly monosaccharides (glucose, fructose 1 : 1) (73%) and a very small percentage of the dissacharide sucrose (0.5) as compared to molasses that contain a high percentage of sucrose (46) and a small percentage of monosaccharides.
Monosaccharides (reducing sugars) are much better preservatives against bacteria and fungi in dates than disaccharides in molasses. Further, dates contain one-fourth the proportion of potassium that is present in molasses. Potassium is known to limit the level of molasses incorporation in poultry and animal feed owing to its laxative effect (Leeson and Summers, 1991). Therefore, dates have been used at much higher levels in poultry, fish and ruminant feeds without any adverse effect in several studies. Wasted dates were used successfully to partially replace yellow maize or barley in feeds for broilers (Azzawi, 1960; Afifi et al., 1966; Hiti and Rous, 1978; Kamel et al., 1981 and Al-Yousef, 1985), egg layers (Nagib et al., 1994), breeder quails (Al-Al-Yousef, 1985), sheep (Al-Dosari et al., 1995), cows (Ali et al., 1956) and fish (Belal and Al-Jasser, 1997).
Practical application of wasted dates in animal feed on an industrial scale has however been difficult owing to their hygroscopic properties (they cannot be kept in powder form). This is due to their high levels of monosaccharides that readily absorb air moisture. In order to overcome this problem, wasted dates would have to be diluted in warm water and mixed with a dietary ingredient (maize, wheat, bran ...etc) in a proportion that could make processing economical. The mixed ingredient could then be dried and crushed into a powder form.
In this study, we evaluated the effect of the proportion of dates in mixtures with either yellow maize or wheat bran on the stability and quality of the mixed ingredients.
2. Materials and methods
2.1. Sample preparation
Ten kilograms of wasted dates from Al-Hassa Date Processing Plant were hand pitted and mixed with each of yellow maize and wheat bran at 11% (0%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45% and 50%). Thus, 22 samples were prepared as follows.
Pitted dates were weighed and blended with water at 708C (at a ratio of 2 ml of water to 1 g of date flesh) until all dates were dissolved and homogenized. Then, the mix was
1Ephestia cautella (Walker), Ephestia kuhniella (Zeller), Ephestia elutella (Hubner), Oryzaephilus
surinamensis(LinneÂ),Cadra dactyliperdaandArnepsis sabella(Hemps).
gradually added to the corresponding weight of the feed ingredient (yellow maize or wheat bran) in a kitchen mixer, while mixing for 25 min until the mix began to clump. The samples were dried in an oven at 60oC for 24 h in a stainless-steel tray. Dried samples were then crushed in a laboratory hammer mill, transferred separately to plastic bags and kept at 2428C for three months before analysis.
2.2. Analysis
Proximate analysis of all ingredients (dates, wheat bran and yellow maize) and all mixes were done separately (Table 1). Each sample was analyzed for dry matter, crude protein, total ash, crude fiber and ether extract (AOAC, 1980), neutral detergent fiber using amylase enzyme (1,4 & D glucan hydrolase E.C. No. 3.2.1.1.) from Bacillus
subtilis in the procedure of Robertson and Van Soest (1981). The contents of starch in wheat bran and yellow maize mixes with dates were calculated (Pomeranz, 1986; Galliard and Bowler, 1987). Numbers of fungi per gramme of mix were determined according to AACC (1984). The following terms are used throughout the manuscript, and are defined as follows:
Pasting time and temperature: the time and the temperature when the resistance to mixing started to increase inside the Amylograph.
Viscosity time and temperature: the time and the temperature when the resistance to mixing reaches its maximum inside the Amylograph.
Viscosity temperature: maximum temperature at which maximum resistance occurs inside the Amylograph.
Maximum viscosity value: the maximum resistance to mixing reached inside the Amylograph, measured in Brabaender unit.
Viscosity measurements were obtained using a Brabaender Amylograph, manufactured by Brabaender BHG, D-4100 Duisburg-1, Germany.
Table 1
Composition of the individual feeds employed and of mixes containing 50% dates (g/kg DM,SE)
Date flesha Wheat bran Dates : bran (50 : 50)
aAccording to Sawaya et al. (1983) date flesh contains 733 g total sugar/kg (glucose : fructose, 1 : 1) and (mg/kg): K, 8960; P, 640; Ca, 260; Mg, 490; Fe, 16.7; Ca, 9.7; Zn. 3.8
Pasting time and temperature and maximum viscosity time, temperature and value were determined as follows.
Sixty grammes of date-mix powder (14% moisture basis) were added to 360 ml diluted phosphate buffer (prepared according to AACC, 1984 method No. 22-10). The contents were well shaken and poured into the Amylograph bowl. The remaining contents were rinsed with 100 ml diluted phosphate buffer. The starting temperature was adjusted to 308C. The Amylograph was then started and the pasting time, temperature and maximum viscosity time, temperature and maximum viscosity values in Brabaender Units (BU) were read from the Amylograph. Distilled de-ionized water was used in this process.
2.3. Statistical analysis
One-way analysis of variance and Duncan's multiple range test were used to compare treatment means for significant differences (Snedecor and Cochran, 1981).
3. Results and discussion
Overall, the problem of the hygroscopic property of date flesh was overcome by mixing it with either ground yellow maize or wheat bran. The products were therefore in an acceptable form (powder) for the feed mill.
Proximate analysis values of date flesh in addition to its sucrose content are shown in Table 1. Sawaya et al. (1983) have reported similar values for the same variety (Riziz at its ripe stage) of date flesh. Dates contain high levels of carbohydrate (797 g/kg) mostly as monosaccharides.
Proximate analysis and neutral detergent fiber of the wheat bran and yellow corn are shown in Table 1. The composition of the mixes with dates was as expected from the composition of the individual feeds, as illustrated by the values for the 50 : 50 mixes in Table 1. Thus, crude protein, crude fat, crude fiber, neutral detergent fiber and total ash were found to decrease as the level of dates increased in either type of mix. This is with exception of total ash content of yellow maize±date mixes, for which no clear trend was found as both yellow maize and date flesh are low in ash content.
It was concluded that the process of preparing and storing for three months (Section 2) did not seem to cause any significant change in the chemical composition described above. That was clear when the figures were compared to their calculated values (NRC, 1983) and the date flesh analysis (Table 1). This indicates that there is no nutrient loss from any of the mixes as a result of their preparation and storage.
The time and temperature needed to start showing an increase in resistance to mixing inside the Amylograph (pasting time and temperature) were slightly reduced but not significantly (p> 0.05) as the levels of dates in the mixes were increased (Figs. 1, 2). This may have been due to the effect of monosaccharides (Table 1) in date flesh on the start of gelatinization (dough making) as reported by Mustafa et al. (1986).
Similarly the time and temperature takes to reach maximum resistance to mixing inside the Amylograph(maximum viscosity temperature and time) were not affected by increasing the level of dates in either of the experimental mixes. As a result the time and
temperature in the pellet making process in feed mills are not going to be affected by the level of dates in the mixes.
Maximum resistance values inside the amylograph (maximum viscosity) which is measured in Brabender units were significantly increased with increasing the level of
Fig. 1. The effect of mixing dates (D) with wheat bran (W) and yellow maize (Y) on pasting time and temperature.
dates in the mixes (Fig. 3). This was due to the thermoplasticity of dates in addition to the starch content (Mustafa et al., 1986).
The maximum viscosity values of date±yellow maize mixes were double those of date± wheat bran mixes. This was due to the fact that yellow maize contains a much higher level of starch than wheat bran. Additionally, yellow maize and wheat bran have different types of starches with different maximum viscosity values. Galliard and Bowler (1987) have shown that different types of starch have different maximum viscosity values.
The increase in maximum viscosity values in both types of mixes as the level of dates was increased, indicated an increase in the binding ability of the mixes. As a result, pellets made from dates and yellow maize (highest maximum viscosity value) are much stronger than those made from dates and wheat bran. Belal and Al-Jasser (1997) have demonstrated a high correlation (r= 0.97) between the level of dates in the feed and binding ability of the pellets.
The number of fungi per gramme of each mix in both types of the test mixes was significantly reduced by increasing date content (Fig. 4). Sugar concentration increases with increasing the level of dates in the mixes. This indicates the preservation capability of dates as it is known that dates preserve themselves from fungal and bacterial infestation to a large extent by their high monosaccharides content. This would partly spare the use of fungistats in animal feeds as it is known that many types of fungus produce toxins and or cause undesired changes in animal feed that affect animal health. In conclusion the products of all wheat bran±date mixes and yellow maize±date mixes are in a form acceptable to the feed mill. Dates have improved the quality of the mixed ingredients by: (a) increasing the maximum viscosity values which would improve the
Fig. 3. The effect of mixing date (D) with wheat bran (W) and yellow maize on maximum viscosity values (Brabender Unit-BU).
process of making pelleted feeds; and (b) preserving both types of mixes against fungal infestation.
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