QUALITY PARAMETERS OF RABBIT MEAT MARKETED IN ZAGAZIG CITY

QUALITY PARAMETERS OF RABBIT MEAT MARKETED IN ZAGAZIG CITY

AlaaEldinM. Morshdy ;Abdallah F.Abdallah

andAhmed M. Al-Ashkar

Food Control Department, Faculty of Veterinary Medicine,

Zagazig University, Zagazig 44519, Egypt.

Key Words:Rabbit meat, Enterobacteriaceae, Staphylococcus, aerobic plate count, most probable number of coliforms.

ABSTRACT:

Twenty samples rabbit carcasses, were randomly collected from supermarkets and poultry and rabbits’ shops at ZagazigCity, Egypt Samples were subjected to both chemical and bacteriological examination. The pH of examined rabbit carcasses ranged from 5.75 to 5.86 with amean value of 5.81 ± 0.03. The total volatile basic nitrogen (TVBN) ranged from 6.14 to 7.27 with a mean value of 6.7 ± 0.33 mg/100g in examined rabbit samples and thiobarbituric acid (TBA) ranged 0.19 to 0.31 with a mean value of 0.25± 0.03mg malonaldhyde/kg for all examined rabbit carcasses. Regarding bacteriological examinations, the APC in shoulder and thigh muscleranged from 5.32 to 7.39 and from 4.48 to 7.76 with mean values of 6.57 ± 6.16 and 6.83 ± 6.40 log₁₀CFU/g, respectively.However, the Staphylococcus count ranged from 3.97 to 5.34 and from 3.08 to 6.00 with mean values of 4.79 ± 4.38 and 4.87 ± 4.69 log₁₀CFU/g in shoulder and thigh. In addition, the Enterobacteriaceae ranged from 3.00 to 6.11 and from 3.00 to 6.41 with mean values of 5.6 ± 4.95 and 5.71 ± 5.2 log₁₀CFU/g in shoulder and thigh.The MPN ranged from 2.97 to 5.38 and from 2.56 to 5.38 with mean values of 4.76 ± 4.22 and 5.02 ± 4.38 log₁₀ CFU/g in shoulder and thigh samples, respectively.In conclusion rabbit meat contaminated with various bacteria which, may cause public health hazards but the chemical parameters within the acceptable level.

INTRODUCTION:

Rabbit meat is characterized by high digestibility, medium-low juiciness, little coarseness, odor and flavor, low-calories, lowest fatty feeling in the mouth and tenderness, rabbit meat is gaining preference by many meat consumers. Compared to red meats, rabbit meat has lower calories (on average 618 kJ/100 g fresh meat), fat (on average 6.8 g/100 g fresh meat), and cholesterol content (on average 53 mg/100 g fresh meat), iron (1.34 mg/100 g), sodium (47 mg/100 g) and energy (119 kcal/100 g) (Mačangaet al., 2011). Rabbit meat fits well the contemporary consumer demand for a low-fat meat with a high degree of unsaturated fatty acids and low cholesterol and sodium levels (Cavaniet al., 2009).

Rabbit meat may be contaminated with various types of food spoilage and food poisoning bacteria which gain access to carcass from living animals during slaughtering, evisceration and further processing.  Aging is one of the most critical factors that influence meat quality. During the aging process, muscle conversion into meat is accompanied by quantitative changes in several metabolites. Consequently, meat becomes unfit for human consumption as it is considered to be spoiled. Spoilage of raw meat accounts greatly for major annual losses to meat processors and retailers (Nattresset al., 2001).Therefore, the study was conducted to evaluate the hygienic status of rabbit meat that sold in Sharkia governorate, Egypt.

MATERIALS AND METHODS:

A total of 20 rabbit carcasses randomly collected, around 2 kg live weight from Zagazig city, Egypt. The collected samples were transferred without delay in an insulated ice box, under complete aseptic conditions, to the laboratory of Meat Hygiene, Faculty of Veterinary Medicine, Zagazig University where they were examined.

Determination of pH according to Pearson (2006); briefly about 10 g of the sample were blended in 10 ml of neutralized distilled water. The homogenate was left at room temperature for 10 min with continuous shaking. The pH value was determined by using an electrical pH meter (Bye model 6020, USA). Total volatile basic nitrogen (TVB-N) content was estimated according to AOAC (1995). The thiobarbituric acid (TBA) content was calculated by the method of Nasr et al. (2017).The preparation of the rabbit meat samples and serial dilutions were performed according to ISO 6887-2 (2003).Brieflytwenty five grams of each rabbit meat sample were homogenized aseptically with mixing in 225 ml of 0.1 % buffered peptone water (BPW, HIMEDIA,  M614-500G) in a stomacher (Colworth, 400) for 2.5 min at room temperature (25^ºCand then allowed to stand for 5 min to provide a homogenate which represents the dilution of 10^-1). Quantity of 1 ml of the homogenate was transferred into a sterile test tube containing 9 ml of 0.1% BPW, then ten-fold serial dilutions were prepared up to the required dilution (10^-9). Enumeration of APC was done according to ISO 4833-1: (2013) using pour plate method of 1ml onto plate count agar (Oxiod CM325) then incubated at 30^O C. However, Staphylococcus count was carried out using Baired-Parker agar medium plates (Oxoid, CM 275) according to ISO, 6888-1: (1999) and Enumeration of Enterobacteriaceae according to ISO 21528-2 (2004) was carried out on violet red bile glucose ager (VRBG, HIMEDIA).Both medium inoculated by spreading 0.1 ml of the ready prepared serial dilutions onto the surface. The agar plates were incubated for 48 h at 37±0.5^°C aerobically.

RESULTS AND DISCUSSION:

Physicochemical parameters of examined rabbit carcasses:

The results in table 1 revealed that the mean value of pH of examined rabbit carcasses ranged from 5.75 to 5.86 with amean value of 5.81 ± 0.03. Acidic pH possesses a bacteriostatic power while alkaline pH promotes microbial growth. Nearly similar findings of 5.77 were obtained in central Mexico City (Chabelaet al. 1999), 5.98 inLeon, Spain (Rodriguez Callejaet al. 2004), 5.95 in Slovak Republic (Mertinet al. 2012), 5.81, 5.88, 5.92, and 5.89 at storage day1, 3, 6, 9, respectively in Hungary (Dal Bosco et al. 2014), 5.9 in Hungary (DalleZotteet al. 2014), 5.99 in Poland Króliczewskaet al. (2018).However, lower results of 5.53 were obtained in Athens, Greece (Simitziset al. (2014), 5.49 (Alagónet al. 2015). Higher results of 6.26 ± 0.20 were obtained in León, Spain (RodriguezCallejaet al. 2005), 6.34 in Italy (Palazzo et al. 2015).

Table (1) Chemical parameters pH, total volatile nitrogen (TVN mg/100g) and thiobarbituric acid (TBA mg malondialdehyde/Kg) of examined rabbit carcasses.

All examined samples were in the range of permissible level reported by ES 1090 (2005) which limited the value of TBA must be not more than 0.9 mg MDA/kg for chicken meat.

The amount of TVBN is a very good chemical indicator of spoilage of the meat. The achieved results in table 1 revealed that the TVBN ranged from 6.14 to 7.27 with a mean value of 6.7 ± 0.33 in examined rabbit samples. Nearly TVB-N of chilled rabbit meat after rigor 8.6 mg/100 g (Lanet al., 2016).All examined samples were in the range of permissible level mentioned by ES 1090 (2005) which limited the content of TVBN must not be over than 20 mg /100g. The obtained data in table 1 showed that TBA ranged 0.19 to 0.31 with a mean value of 0.25± 0.03mg malonaldhyde/kg for all examined rabbit carcasses. Nearly similar findings of 0.261 to 0.278in Zagazig, Egypt (Nasr et al., 2017). Lower values (0.09) were obtained in central Italy 0.07 in Italy (Dal Boscoet al. 2015^a&b), and0.07 in Hungary (Mattioliet al. 2016). However, higher results of 2.16 were obtained in Canada (Koneet al. 2016), 2.16 in Laprodéo, Canada (Króliczewskaet al. 2018).

Bacteriological parameters of examined rabbit carcasses:

The APC ranged from 5.32 to 7.39 and from 4.48 to 7.76 with mean values of 6.57 ± 6.16 and 6.83 ± 6.40 log₁₀CFU/g in shoulder and thigh as shown in table 2. Nearly similar count 6.021 log₁₀CFU/g in rabbit meat collected from Egypt Badr (2004). Lower APC obtained 8 x 10⁵ ± 3 x 10³ CFU/g in rabbit meat collected from BeniSuef city, Egypt Khalafalla (1993),4.96 ± 0.90 log CFU/g in Spain  (Rodriguez Callejaet al., 2004),  2.75 x 10³ ±1.3 x 10³  log CFU/g in Mexico (Velázquez et al. 2008),ranged from 4 to 5 log₁₀CFU/g Nakyinsigeet al. (2014) and5.34 log₁₀ CFU/g from Czech Republic (Cwiková and Pytel 2017). The variation in the count may be attributed to neglected hygienic practices, exposure to condition favoring bacterial proliferation, and contamination of meat from different sources as fur of rabbits, atmosphere, visceral content, transport, packaging utensils and also the water used for cleaning of equipment and personal use.

Table (2): Bacteriological parameters (log₁₀CFU/g) of examined rabbit carcasses  (N = 20, each).

 N= Number.

SE= Standard Error of means.

^(a,b,c) different superscript letters for same parameter indicate significant differences (p < 0.05).

        The Staphylococcus count ranged from 3.97 to 5.34 and from 3.08 to 6.00 with mean values of 4.79 ± 4.38 and 4.87 ± 4.69 log₁₀CFU/g in shoulder and thigh as shown in table 2.Lower counts obtained 4x 10³ ± 4 x 10² CFU/g in rabbit meat collected from BeniSuef city, Egypt Khalafalla (1993), 0.49 ± 0.45 log₁₀CFU/g in Spain  (Rodriguez Callejaet al., 2005).

The Enterobacteriaceae ranged from 3.00 to 6.11 and from 3.00 to 6.41 with mean values of 5.6 ± 4.95 and 5.71 ± 5.2 log₁₀CFU/g in shoulder and thigh as shown in table 2. Nearly similar count obtained 5.17log₁₀CFU/g (Lópezet al. 2002). Meanwhile, lower counts obtained 4 x 10⁴ ± 8 x 10³ CFU/g in rabbit meat collected from BeniSuef city, Egypt Khalafalla (1993), 4.295 log₁₀CFU/g in Mexico City (Chabelaet al., 1999), 4.785 log₁₀ CFU/g in Egypt Badr (2004), 1.18 ± 1.35 log₁₀CFU/g in Lisbon, Portugal (Pereira and Malfeito-Ferreira 2015), 3.12 ± 0.34 log₁₀ CFU/g in Italy (Albonettiet al. 2017) and2.9 log₁₀ CFU/g from Czech Republic (Cwiková and Pytel 2017).

The MPN ranged from 2.97 to 5.38 and from 2.56 to 5.38 with mean values of 4.76 ± 4.22 and 5.02 ± 4.38 MPN/g in shoulder and thigh as shown in table 3. Lower MPN detected 2.4 x 10³ ± 9.1 x 10² log CFU/g in Mexico (Velázquez et al. 2008) and E.coli count ranged from 2.5 to 3 log₁₀CFU/g Nakyinsigeet al. (2014).The presence of coliforms at 45 °C in foods suggests the presence of fecal contamination, since there is a high incidence of E. coli in this group, which has as its primary habitat humans and animals intestines. However, coliforms at 45 °C also include some strains that can be found in other habitats (plants and soil) like Enterobacter and Klebsiella. For that reason, the direct correlation between this group and the one originating from fecal contamination should be considered cautiously (Silva et al., 2006).

In conclusion rabbit meat contaminated with various bacteria which, may cause public health hazards but the chemical parameters within the acceptable level.

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مقاییس الجودة للحوم الأرانب المسوقة فى الزقازیق

علاء الدین محمد مرشدى، عبدالله فکرى عبدالله و أحمد محمد طلبة الأشقر

قسم مراقبة الأغذیة –کلیة الطب لبیطرى –جامعة الزقازیق

تم جمع 20 ذبیحة أرانب بشکل عشوائی ، حوالی 2 کجم من الوزن الحی من مدینة الزقازیق ، مصر. تم نقل العینات التی تم جمعها دون تأخیر فی صندوق ثلج معزول تحت ظروف معقمة کاملة إلى معمل صحة اللحوم بکلیة الطب البیطری بجامعة الزقازیق حیث تم فحصها وتبین من الفحص أن جمیع العینات التى تم فحصها صالحة من الناحیة الحسیة. وتبین من نتائج الفحص الکیمیائى أن الأس الهیدروجینى تراوح بین 5.75 الى 5.86 ومتوسط 5.81 ± 0.03. وجد من النتائج أن النسبة الکلیة للمواد النیتروجینیة المتطایرة 6.7 ± 0.33  مجم /100جم. وتراوحت نسبة حمض الثیوباربتیورک فى العینات المفحوصة من 0.19 الى 0.31 ومتوسط 0.25± 0.03 مجم مالون داى ألدهید/ کجم. واتضح من نتائج الفحص البکتیرى أن العدد الکلى للبکتریا الهوائیة 6.57 ± 6.16 و 6.83 ±  6.4 ، العدد الکلى للمکورات العنقودیة  4.79 ± 4.38 و 4.87 ± 4.69 ، العدد الکلى للبکتریا المعویة 5.6 ± 4.95 و 5.71 ± 5.2  لوغارتم 10 مستعمرة بکتیریة / جرام  وکان العدد الأحتمالى للمیکروبات القولونیة 4.76± 4.22 و 5.02 ± 4.38 لوغارتم 10 عدد أحتمالى / جرام  فى الکتف والفخذ على الترتیب. خلصت الدراسة أن لحوم الأرانب ملوثة بانواع مختلفة من البکتیریا والتی قد تسبب مخاطر على الصحة العامة ولکنها مقبولة من الناحیة الکیمیائیة.