Microbial load, acidity, lipid oxidation and volatile basic nitrogen of irradiated fish and meat-bone meals

Microbial load, acidity, lipid oxidation and volatile basic nitrogen of irradiated fish and meat-bone meals

Bioresource Technology 98 (2007) 1163–1166 Microbial load, acidity, lipid oxidation and volatile basic nitrogen of irradiated Wsh and meat-bone meals...

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Bioresource Technology 98 (2007) 1163–1166

Microbial load, acidity, lipid oxidation and volatile basic nitrogen of irradiated Wsh and meat-bone meals M.R. Al-Masri

a,¤

, M. Al-Bachir

b

a

b

Department of Agriculture, Atomic Energy Commission, P.O. Box 6091, Damascus, Syria Department of Irradiation Technologies, Atomic Energy Commission, P.O. Box 6091, Damascus, Syria Received 27 March 2006; received in revised form 26 April 2006; accepted 13 May 2006 Available online 24 July 2006

Abstract Experiments were carried out to study the eVect of diVerent doses of gamma irradiation (0, 5, 10, 15 and 20 kilo gray; kGy) on some nutritive components and chemical aspects pertaining to quality of Wsh meal and meat-bone meal. The radiation doses required to reduce the total microbial load and Salmonella sp. one log cycle (D10) in Wsh meal and meat-bone meal were determined. Results indicated that gamma irradiation of Wsh meal and meat-bone meal with 5–20 kGy doses had no eVects on the total acidity values but increased the values of lipid oxidation and total volatile basic nitrogen. D10 of total microbial load and Salmonella sp. were 833 and 313 Gy for Wsh meal and 526 Gy and 278 Gy for meat-bone meal, respectively. It can be concluded that radiation processing could be employed in the recycling of Wsh and meat-bone meals by using them as feedstuVs in poultry diets with no fear of losing their nutritive components. © 2006 Elsevier Ltd. All rights reserved. Keywords: Decontamination; Irradiation; Nutrients; Animal by-product

1. Introduction Recycling of animal protein by-products is very useful for economical and environmental aspects. Fish and meatbone meals are used as feed supplements for animals to cover their requirements of animals for protein and essential amino acids that stimulate growth and productive performance (Granz, 1982). One of the problems arising from the use of animal protein by-products in poultry feeds is their susceptibility of being carriers of pathogenic organisms such as Salmonellae to animals and humans causing serious health problems. A positive eVect of irradiation (25–35 kGy) was observed in the process of sterilization of animal diets (Ito and Iizuka, 1979). Feeding of broiler chicks with irradiated meat-bone meal had no negative eVect on their productive performance, eYciency of protein, apparent

*

Corresponding author. Fax: +963 11 6112289. E-mail address: [email protected] (M.R. Al-Masri).

0960-8524/$ - see front matter © 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.biortech.2006.05.026

metabolizable energy and biological aspects of their digestive tract (Al-Masri, 2003a,b). The aim of the present work was to study the eVect of gamma radiation on microorganisms load and chemical aspects pertaining to quality of Wsh and meat-bone meals in order to use them as feed supplements in poultry diets. 2. Methods The samples of meat-bone meal were collected from a local commercial market; whereas, the samples of steamdried Wsh meal were originally imported from Chile. After good mixing, three-replicate samples of meat-bone meal and Wsh meal (each about 450 g) were packed in polyethylene bags, sealed and then irradiated with gamma rays at doses of 0, 5, 10, 15 and 20 kGy using a 60Co source (48.59 kCi) at a dose rate of 3100 Gy/h, under uniWed conditions of temperature (24 °C) and humidity (about 50%). The absorbed dose was determined using alcoholic chlorobenzene dosimeter (Cserep et al., 1971). The total acidity

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was obtained by a direct titration with NaOH using phenolphthalein indicator and was calculated as 1.0 ml of (0.1 M) NaOH equivalent to 0.009 g lactic acid (Egan et al., 1987). Total volatile basic nitrogen was determined according to Pearson (1976). Lipid oxidation in terms of mmol O2/g sample was determined by the modiWed method of Buege and Aust (1978). The radiation doses required to reduce the total microbial load and Salmonella sp. one log cycle (D10) in Wsh meal and meat-bone meal were determined. Isolated microbes from the original samples and pure culture of Salmonella sp. were used for contamination the studied samples. Diluted water suspension of Salmonella or other microbes (1 ml solution/10 g sample) were used for the contamination. After that, survival curve was estimated for irradiation doses of 200, 400, 600, 800 and 1000 Gy. Three-replicates were used for D10 determination. The survival level of Salmonella was determined by plate counting on Xylose Lysine Desoxycholate Agar (XLD) after two days of incubation at 37 °C. Microbiological loads of the experimental samples were evaluated according to the standard methods of the AOAC (1986). Aerobic Plate Counts (APCs) were enumerated on a plate count agar (Oxoid, CM 325) medium after triplicate plating and incubating at 37 °C for 48 h to determine the total plate counts of microbes. Results were subjected to analysis of variance (ANOVA) using the “Statview, version 4.4” program (Abascus Concepts, Berkeley, CA, USA) to test the eVect of irradiation dose and means were separated using the Fisher’s least signiWcant diVerence (LSD) test at the 95% conWdence level. D10 value was calculated using cricket graph computer package. 3. Results and discussion 3.1. Microbial quality The total microbial loads in the studied samples were originally low and this might be attributed to the heat pertreatment of the rough samples (Table 1). However, Salmonellae were not detected in the original samples. Therefore, the radiation doses required to reduce the microbial load and Salmonella sp. one log cycle (D10) in the studied samples were determined. D10 value was inXuenced by the art of Table 1 EVect of gamma irradiation on the microbial load and Salmonellae of Wsh meal (FM) and meat-bone meal (MBM) Dose (kGy)

Control 5 10 15 20

Total count (microb/g)

Salmonellae

FM

MBM

FM

MBM

131 § 57b <10a <10a <10a <10a

245 § 34b <10a <10a <10a <10a

ND E E E E

ND E E E E

Means within a column followed by similar letters do not diVer signiWcantly (P > 0.05). ND: not detected.

Table 2 D10 of Salmonella sp. and total microbial count for Wsh meal (FM) and meat-bone meal (MBM) Salmonella sp.

D10(Gy)

Total count

FM

MBM

FM

MBM

313

278

833

526

the animal by-product. D10 values for microbial load and Salmonella sp. were in Wsh meal higher than that in meatbone meal (Table 2). Thayer (2003) reported that the D10 values (616 Gy) of Salmonella sp. in meat (ground beef) were higher than that in our results. Ito et al. (1981) indicated that the microbial loads of the poultry feed containing Wsh meal and meat-bone meal were between 35 £ 103 and 22 £ 105 per 1 g, and that an irradiation treatment with a 5-kGy dose decreased the microbial loads to less than 10 microbes per 1 g. Kume et al. (1981) reported that the chicken feeds contain between 24 £ 103 and 39 £ 105 microbes per 1 g and the irradiation treatment with 5-kGy dose was eVective to decrease the microbial loads signiWcantly. Mossel (1979) indicated that irradiation of feed rations with 3-kGy dose was eVective to remove the pathogenic organisms such as Salmonellae. However, ElZawahry et al. (1986) and Adler et al. (1978) recommended to use a 10-kGy irradiation dose to remove Salmonellae and other pathogenic organisms in the feed rations. Irradiation of fresh chicken (Lacroix et al., 1998) and meat products (Paul et al., 1998) with a dose of 2.5 kGy was eVective in controlling Salmonella contamination. Katta et al. (1991) reported that a higher dose than 2.5 kGy may be required for a complete elimination of Salmonella in chicken. The eVect of gamma irradiation on microorganisms may interact directly with a sensitive site in the organism, usually the deoxyribonucleic acid (DNA) that directs cellular reproduction and synthesis of cell components, rather than the relatively radiation-resistant constituents (Yeager and O’Brien, 1983). 3.2. Chemical parameters of irradiated Wsh and meat-bone meals The changes in chemical aspects pertaining to quality of the experimental animal protein by-products treated with diVerent doses of gamma irradiation are illustrated in Table 3. Irradiation treatments with 5-kGy and 10-kGy doses had no signiWcant (P > 0.05) eVects on the values of total acidity of Wsh and meat-bone meals. Total acidity values increased in irradiated meat-bone meal with 15-kGy and 20-kGy doses in comparison with the control. Al-Bachir and Mehio (2001) reported no diVerence in the total acidity values of irradiated meat with 1–4 kGy doses. There were no signiWcant changes in the lipid oxidation values of Wsh meal among the irradiation treatments 5, 15 and 20 kGy. The lipid oxidation values increased signiWcantly (P < 0.05) in the treated Wsh and meat-bone meals with a 5-kGy dose. Kanatt et al. (1997) found that irradiated

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Table 3 EVect of gamma irradiation on some chemical aspects of Wsh meal and meat-bone meal Total acidity (% lactic acid)

Lipid oxidation (mmol O2/kg)

Volotile basic nitrogen (mg/kg)

Animal by-product

Dose (kGy)

Fish meal

0 5 10 15 20

1.56 § 0.14a 1.68 § 0.16a 1.67 § 0.10a 1.79 § 0.15a 1.57 § 0.06a

0.008 § 0.001a 0.013 § 0.002b 0.008 § 0.001a 0.011 § 0.011b 0.011 § 0.001b

252 § 28a 277 § 19a,b 281 § 4a,b 300 § 8b 234 § 24a

Meat-bone meal

0 5 10 15 20

14.6 § 0.40a 14.4 § 0.70a 16.9 § 0.40a 18.4 § 1.80b 18.8 § 2.70b

0.008 § 0.003a 0.040 § 0.001b 0.000 § 0.000c 0.009 § 0.002a 0.028 § 0.005d

982 § 92a 1351 § 181b 1364 § 67b 1354 § 172b 1391 § 18b

Means within a column followed by similar letters do not diVer signiWcantly (P > 0.05).

meat showed a slight increase in lipid peroxidation in terms of thiobarbituric acid values on storage as compared with non-irradiated meat. Nawar (1985) reported that irradiation in the presence of oxygen accelerated the auto-oxidation of fats by possibly one of the following three reactions: (1) formation of free radicals which combine with oxygen to form hydroperoxides; (2) breakdown of hydroperoxides; or (3) destruction of antioxidants. Irradiation treatment of Wsh meal with 15 kGy dose and of meat-bone meal with 5–20 kGy doses increased signiWcantly (P < 0.05) the values of total volatile basic nitrogen. There were no signiWcant changes in the values of total volatile basic nitrogen of Wsh and meat-bone meals among the irradiation treatments 5, 10 and 15 kGy. Al-Bachir and Mehio (2001) found no changes in the total volatile basic nitrogen values of irradiated meat with 2, 3 and 4 kGy doses. It is concluded from the present study that radiation processing was eVective to decrease the microbial loads and the Salmonella sp. of the Wsh and meat-bone meals with no fear of losing their nutritive components. Acknowledgements The authors would like to thank the General Director of the Syrian Atomic Energy Commission for his support. Thanks are also dew to Mr. M. Mardini, M.A. Al-Adawi and U. Hasan for their assistance in the laboratory analyses. References Adler, J.H., Eisenberg, E., Lapidot, M., Tsir, D., 1978. Food preservation by irradiation. In: Proceedings of an International Symposium Jointly Organized by IAEA, FAO and WHO, Wageningen, 21–25 November 1977. IAEA (International Atomic Energy Agency), Vienna, vol. 2, pp. 243–254. Al-Bachir, M., Mehio, A., 2001. Irradiation luncheon meat: Microbiological, chemical and sensory characteristics during storage. Food Chem. 75, 169–175. Al-Masri, M.R., 2003a. Productive performance of broiler chicks fed diets containing irradiated meat-bone meal. Bioresource Tech. 90, 317–322. Al-Masri, M.R., 2003b. Changes in apparent metabolizable energy and digestive tract of broiler chickens fed diets containing irradiated meatbone meal. Radiat. Phys. Chem. 67, 73–77.

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