Short communication
Quality characteristics of broiler blood meal
as affected by yeast, glucose oxidase,
and antioxidant treatments
G.W. Lu, T.C. Chen
*Poultry Science Department, Mississippi State University, Mississippi State, MS 39762, USA
Received 26 March 1999; received in revised form 9 September 1999; accepted 8 November 1999
Abstract
Effects of deglucosing and antioxidant treatments on quality characteristics of broiler blood meal were studied. Broiler blood was dried and ground with deglucosing and antioxidant addition. The non-deglucosed blood powder was darker, less red and yellow in color than those of the deglucosed. Yeast deglucosed blood meal had the lowest lysine availability as measured by the ¯uorodinitrobenzene method. Glucose oxidase desugarization improved (p< 0.05) the lysine availability of blood powder. Treatment of broiler blood with glucose oxidase and antioxidant
combination improved lysine availability by preventing an increase in TBA values. # 2000
Elsevier Science B.V. All rights reserved.
Keywords:Broiler; Blood meal; Deglucosing; Quality
1. Introduction
Traditionally, poultry blood has been processed into feed-grade as blood meal or blended with poultry by-products for poultry offal meal (Mountney, 1966). Lysine is the ®rst or second most limiting amino acid in the diets of pigs and chickens, respectively (Seerley, 1991). Poultry blood is an excellent source of lysine. The lysine content of chicken blood meal varies with the method of drying from 100±200 g/kg for spray drying to 60±80 g/kg for vat drying (Ockerman and Hansen, 1988).
Broiler blood contains 130±260 mg/dl glucose (Swenson, 1977). During the blood meal drying processing, Maillard reaction might occur. This reaction results in the
83 (2000) 159±164
*Corresponding author. Tel.:1-601-325-3416; fax:1-601-3258292. E-mail address: [email protected] (T.C. Chen).
formation of covalent linkages between the 2-NH2of lysine and carboxylic groups of glucose of heat-damaged proteins. Such lysine units do not have a reactive2-NH2group even though lysine is regenerated from them during acid hydrolysis (Carpenter, 1973). Fluorodinitrobenzene (FDNB) is used to label free amino groups of proteins and peptides. Each free amino group reacts with a dinitrophenyl group, and this FDNB-reactive lysine value represents the amount of available lysine for animal metabolism (Carpenter, 1973). In dried egg production, a microbial fermentation process or a glucose oxidase enzyme system was used to desugarize the liquid egg prior to drying. Boctor and Harper (1968) reported that when egg white plus 2% glucose was autoclaved at 1218C for 12 h, its FDNB-reactive lysine value fell by 40%. Studies have shown that the presence of oxidized oil reduced the protein nutritional levels by allowing aldehydes to react with proteins and decrease the FDNB-lysine availability (Carpenter, 1973). In view of these reports, in broiler blood meal drying, deglucosing and the addition of antioxidant might produce a better quality product. Therefore, the objectives of this study were to investigate the effects of deglucosing and antioxidants on broiler blood meal quality.
2. Materials and methods
2.1. Broiler blood meal preparation
Broiler blood was collected in plastic bags from a poultry processing slaughter line and frozen immediately at ÿ188C. Prior to deglucosing, the frozen blood was thawed at 21.58C and blended in a Waring blendor at high speed for 1 min.
Blood was deglucosed by either baker's yeast (0.3% W/W, Fleischmann's yeast Oakland, CA) or glucose oxidase (0.4 mg/ml, 7200 units/g solid, Sigma, St. Louis, MO). Mixtures were incubated at 21.58C on a shaker (MSB-1122A-1, Blue M Electric Blue Island, IL) rotated at 120 cycles/min.
A YSI Model 27 Industrial Analyzer (Yellow Springs Instrument, Yellow Springs, OH) was used to measure the glucose content of the yeast deglucosed blood. For those blood samples deglucosed by glucose oxidase, the glucose content was measured by applying one drop of blood sample onto a glucose test strip, and then reading on a glucose meter (One Touch Basic Lifescan, Johnson±Johnson, Milpitas, CA).
The control, antioxidant added [0.02% (W/W), Tenox II (Eastman Chemical, 20% BHA, 6% propylgallate, and 4% citric acid in propylene glycol) (Moerk and Ball, 1974)], deglucosed, or deglucosed and antioxidant added blood samples were pan dried at 558C in a water bath, coincident with air circulation (Bergquist, 1964). After drying, samples were ground through a hammer mill with a 40 mesh screen. The moisture content of the ground product ranged between 70 and 80 g/kg.
2.2. Analysis
2.2.1. Color
A Hunter Model D-25 Color and Color Difference Meter (Hunter Associates Laboratory, VA) was used for color measurement. Standard plate #6279 (with `L' value of 22.8, `a' value ofÿ1.0, and `b' value ofÿ0.4) was used as a reference.
2.2.2. 2-Thiobarbituric acid (TBA) value
The TBA values of samples were measured according to the method of Tarladgis et al. (1960). One gram of blood meal was used instead of 10 g, as described in the method.
2.2.3. FDNB-reactive lysine
Procedures, as described by Booth (1971) for FDNB-lysine tests, were followed. Serial dilutions of2-N-dinitrophenyl-lysine hydrochloride (DNP-Lys HCl) (ICN Biomedicals) were used as standards.
2.3. Statistical analysis
Data were analyzed using the analysis of variance in the general linear models (GLM) procedure of the statistical analysis system (SAS) (SAS/STAT, 1988). When signi®cant treatment differences (p< 0.05) were detected, means were separated using Duncan's new multiple range test (Duncan, 1955).
3. Results and discussion
3.1. Deglucosing of broiler blood
The glucose content of broiler blood averaged 135.0 mg/ml. The chickens were withdrawn from feed before slaughter; therefore, the glucose reading was lower when compared to normal chicken blood glucose content, which ranged from 130 to 260 mg/dl (Swenson, 1977). Baker's yeast and glucose oxidase both reduced (p< 0.01) broiler blood glucose content. When blood was deglucosed by using baker's yeast (0.3% W/W), 1.5 h were required by shaking at 120 cycles/min at 21.58C; while, 4 h were required for glucose oxidase (0.4 mg/ml) (Fig. 1).
Fig. 1. Glucose content of broiler as affected by the addition of yeast (0.3% W/W) or glucose oxidase (0.4 mg/ ml).
3.2. Color
The deglucosed broiler blood meals were lighter (higher Hunter `L' value), more reddish (higher in Hunter `a' value) and yellow (higher Hunter `b' values) than those of the non-deglucosed controls (Table 1). The difference in product color might have been due to the Maillard reaction taking place in the controls. In addition, the color of baker's yeast powder and the production of hydrogen peroxide during glucose oxidase deglucosing might have also contributed to the lighter color of the deglucosed blood meals (Baldwin et al., 1953; Scott, 1953). Hydrogen peroxide has a bleaching effect on the blood meal (Ockerman and Hansen, 1988). The yeast deglucosed blood meal was the lightest (p< 0.01), while glucose oxidase deglucosed blood meal was the yellowest (p< 0.01) in color.
3.3. Lysine availability and TBA value
Glucose oxidase deglucosing improved (p< 0.05) blood lysine availability (Table 1). Yeast deglucosed blood meal had the lowest (p< 0.05) available lysine level. This might be due to the utilization of lysine by yeast during the deglucosing process.
Meade (1956) reported that adding an antioxidant during ®sh meal processing, lysine availability was improved. However, in our study, antioxidant alone did not (p> 0.05) improve the lysine availability of chicken blood meal. Deglucosing by glucose oxidase followed by the addition of antioxidant would improve its lysine availability by lowering its TBA values (Table 2). The TBA reactive products react with proteins and decrease the FDNB-lysine availability (Carpenter, 1973). Glucose oxidase deglucosed blood meal had higher (p< 0.01) TBA readings than other meals, which might be due to the production of O2and H2O2during the deglucosing process (Scott, 1953). The TBA value has been used widely to measure the degree of autooxidation of lipid containing substances. It has also been correlated organoleptically with rancidity. Antioxidants retard oxidative rancidity by
Table 1
Hunter color values and FDNB-lysine availability of broiler blood meal powders as affected by deglucosinga
Observations Controld Deglucosedb,d SEMc Yeast
FDNB-lysine (g/kg) 90.3 AB 87.9 B 94.5 A 0.7
aMean of four replications.
bYeast (Fleischmann's Yeast, Oakland, CA) or glucose oxidase (7200 units/g solid, Sigma, St. Louis, MO)
was added and incubated at 120 cycles/min at 21.58C.
cStandard errors of the mean.
dMeans within a row not followed by the same letter are different (p< 0.05).
inhibiting or interfering with free radical formation which is fundamental to lipid oxidation.
A slight improvement in FDNB value indicated a much greater improvement in available lysine as measured by animal growth. Results demonstrated that the glucose content of broiler blood can be removed to reduce or prevent Maillard reaction. The deglucosed blood meals were lighter, more red and yellow in color than the non-deglucosed meals. Antioxidants alone did not improve (p> 0.05) the lysine availability; however, a combination of glucose oxidase and antioxidant improved blood meal quality by reducing its TBA values.
References
Baldwin, R.R., Campbell, H.A., Thiessen Jr., R., Lorant, G.J., 1953. The use of glucose oxidase in the processing of foods with special emphasis on the desugaring of egg white. Food Tech. 7, 275±282.
Bergquist, D.H., 1964. Eggs. In: Van Arsdel, W.B., Copley, M.J. (Ed.), Food Dehydration. The AVI Publishing Co., Inc. Westport, CT, pp. 652±693.
Boctor, A.M., Harper, A.E., 1968. Measurement of available lysine in heated and unheated foodstuffs by chemical and biological methods. J. Nutr. 94, 289±296.
Booth, V.H., 1971. Problems in the determination of FDNB-available lysine. J. Sci. Food Agric. 22, 658±666. Carpenter, K.J., 1973. Damage to lysine in food processing. Its measurement and its signi®cance. Nutr. Abstr.
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Table 2
FDNB-lysine availability and TBA values of blood meal as affected by the addition of antioxidant and deglucosinga
Treatment FDNB-lysine (g/kg)b TBA valueb
Control 88.6 B 0.296 B
Controlantioxidantc 88.7 B 0.112 C
Glucose oxidased 92.9 A 0.649 A
Glucose oxidaseantioxidant 93.5 A 0.290 B
SEMe 0.6 0.009
aMean of four replications.
bMeans within a column not followed by the same letter are different (p< 0.05).
cAntioxidant, Tenox II (20% BHA, 6% Propylgallate, and 4% citric acid in propylene glycol), was added
0.02% (W/W).
dGlucose oxidase (7200 units/g solid, Sigma, St. Louis, MO) was added and incubated at 120 cycles/min at
21.58C.
eStandard errors of the mean.
SAS/STAT, 1988. SAS/STAT User's Guide, Release 6.03, SAS Institute Inc., Cary, NC.
Scott, D., 1953. Glucose conversion in preparation of albumen solids by glucose oxidase±catalase system. J. Agric. Food Chem. 1, 727±730.
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