INDICATOR MICROORGANISMS AS INDICES OF QUALITY FOR MILK AND SOME DAIRY PRODUCTS | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Assiut Veterinary Medical Journal | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Article 6, Volume 64, Issue 158 - Serial Number 3, July 2018, Page 40-48 PDF (254.24 K) | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Document Type: Research article | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| DOI: 10.21608/avmj.2018.168949 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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| Authors | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| ADEL EL-KHOLY1; GAMAL HASSAN1; MOHAMED EL-SHATER2; AMANY BAKR2 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| 1Food Hygiene Department, Faculty of Veterinary Medicine, Beni-Suef University, Egypt | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| 2Animal Health Research Institute, Egypt | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Abstract | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| A total of 150 samples including raw cow's milk, pasteurized milk, small scale ice cream, large scale plain and flavored yoghurt (30 of each) were collected randomly from dairy shops, super markets and small scale ice cream producers in Fayoum city, Egypt and examined for sanitary and microbiological status. The result revealed that the mean value of titratable acidity % in plain and flavored yoghurt were 1.41± 0.02 and 1.67± 0.04, respectively. The mean values of total Coliforms were 7.5×105± 3.9×105, 8.25×102± 5.04×102, 8.2×104± 4.1×104, 4.83×102 ± 3.15×102 and 2.72×103± 9.5 ×102 cfu/mlorg., respectively. While the mean values of Faecal coliforms were 2.8×104± 1.5×104, 1.16×102 ± 7.11×10, 1.02×103 ±1.71×102, 2.01×10± 1.07×10 and 3.13×102± 1.30×102 cfu/mlorg., respectively. The mean values of E.coli were1.38×103± 6.89×102,1.84×10 ± 9.5, 4.87×102±1.18×102, 1.36×10± 8.4 and 4.68×10± 1.50×10 cfu/mlorg. The mean values of Enterococci were 1.12×106± 1.29×105, 2.1 ×103± 4.20×102, 1.1 ×106 ±1.87×105, 2.23×103± 6.29×102 and 7.77×103±1.67×103 cfu/mlorg., respectively. Staph. aureus was detected in the examined raw cow's milk and small scale ice cream samples, with the mean values of 1.98×105 ± 3.91×104 and 7.65×104 ± 2.41×104 cfu/mlor g., respectively, but was not detected in the other samples. Total yeasts and moulds were detected in the examined large scale plain and flavored yoghurt samples with mean values of 1.15×10²± 3.59×10 and 4.48×10²± 8.17×10 (cfu/mlor g.), respectively. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Keywords | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Key words: Raw cow's milk; pasteurized milk; ice cream; plain yoghurt; flavored yoghurt; coliforms; E.coli; enterococci; Staph.aureus; yeasts; moulds; titratable acidity | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Assiut University web-site: www.aun.edu.eg
INDICATOR MICROORGANISMS AS INDICES OF QUALITY FOR MILK AND SOME DAIRY PRODUCTS
ADEL EL-KHOLY 1; GAMAL HASSAN 1; MOHAMED EL-SHATER 2 and AMANY BAKR 2
1 Food Hygiene Department, Faculty of Veterinary Medicine, Beni-Suef University, Egypt 2 Animal Health Research Institute, Egypt
Received: 7 June 2018; Accepted: 25 July 2018
INTRODUCTION
Milk is considered the most prevalent food stuff among consumers. Where it supply the body with the nutritional needs from protein, fat, carbohydrates, minerals, fat and water soluble vitamins which are necessary for growth and building body tissue. Ice cream is a nutritionally enrichedcongealed dairy product consumed by all ages especially children during summer (El-Sharef et al., 2006).Yoghurt is the best popular cultured dairy products all over the world. Its consumption is associated with several types of human health benefits, including its effect against development of colon tumors (Wollowski et al., 2001). Milk and dairy products are subjected to spoilage or contamination with pathogens during production, handling, processing and distribution
Corresponding author: Dr. AMANY BAKR E-mail address: a_mb87@yahoo.com Present address: Animal Health Research Institute, Egypt
(Fernandes, 2009). Therefore the microbial content of milk and dairy products are a major feature in determining their quality (Queslati et al., 2011). Several routine examinations such as coliform count, enterococcus count, Staph.aureus count and yeasts & moulds count are generally accepted to test the quality of milk and dairy products. Results of these examinations are used to correct unhygienic production and processing and to serve as a guide to improve the quality of milk and dairy products.
Therefore, this study was planned to throw light on quality condition of milk and some dairy products by applying some chemical and microbiological examinations.
MATERIALS AND METHODS
1- Collection of samples A total of one hundred and fifty samples including raw cow's milk, pasteurized milk, small scale ice cream, large scale plain and flavored yoghurt (30 of each) were collected randomly from dairy shops, super markets and small scale ice cream producers.
The samples were delivered to the laboratory in an insulated ice box and examined at the same day.
2. Determination of acidity % in yoghurt samples was done according to the technique detected by (Ling, 1963).
3. Microbiological examination:
3-1- Preparation of samples (APHA, 1992a). 11 ml/g. of well mixed raw cow's milk, pasteurized milk and yoghurt samples were added to 99 ml of sterile peptone water 0.1% to make a dilution of 1/10 from which 10-fold serial dilutions were made up.
3-2- Preparation of Ice cream samples. 11 g. of well mixed ice cream samples after melting at room temperature (25°C) were added separately to 99 ml of sterile peptone water 0.1% and well mixed to prepare a dilution of 1:10; from which ten –fold serial dilutions were made.
3-3- Total coliform count (MPN) using lauryl sulphate tryptose (LST) broth and Brilliant-green Lactose Bile 2% broth (APHA, 1992a).
3-4- Faecal coliform count by using EC broth (APHA, 1992a).
3-5- E. coli count by using Eosine Methylene Blue agar (EMB) (APHA, 1992a).
3-6- Enumeration and isolation of enterococci by using Kanamycin Aesculin Azide agar plates (Mossel et al., 1978).
3-7- Identification of enterococci (Facklam and Collins, 1989).
3-8- Enumeration, isolation and identification of Staph.aureus by using Baired parker's agar (APHA 1992b).
3-9- Total yeasts and moulds count by using Sabouraud Dextrose agar (APHA, 1985).
RESULTS
Table 1: Statistical analytical results of titratable acidity % in examined yoghurt samples (plain and flavored)
Table 2: Statistical analytical results of total coliform count (cfu/ml or g.) in the examined samples.
Table 3: Statistical analytical results of faecal coliform (cfu/ml or g.) in the examinedsamples.
Table 4: Statistical analytical results of E.coli true faecal type count (cfu/mlor g.) in the examined samples.
Table 5: Statistical analytical results of Entercocci count (cfu/mlorg.) in the examined samples.
Table 6: Incidence of the isolated Enterococcus species from the examined samples
Table 7: Statistical analytical results of staph.aureus count (cfu/mlorg.) in examined samples
Table 8: Statistical analytical results of total yeasts and moulds count (cfu/g.) in the examined yoghurt samples/g
DISCUSSION
1. Sanitary examination (The titratable acidity % of yoghurt):- Inspection of Table 1 showed that the titratable acidity % of examined plain yoghurt samples ranged from 1.21 to 1.59 with a mean value of 1.41 ± 0.02. Lower results of titratable acidity % were reported byAbou El-Makarem (2013) while similar results were obtained by El- Kasas (2004) andEl-Asuoty (2011). The titratable acidity % of examined flavored yoghurt samples ranged from 1.32 to 1.99 with a mean value of 1.67 ± 0.04 Lower results of titratable acidity % were detected by El- Le boudy et al. (2017), while similar results were demonstrated byKüçüköner and Tarakçi (2003), while, higher results were shown byEl- Kasas (2004).
There is a variation in percentage of titratable acididty may be due to the percentage of the inoculum starter, incubation time and temperature of yoghurt storage (Walstra et al., 1999).
2. Micobiological examination:- 2.1- Total coliforms: It is evident from Table 2 that total coliforms were detected in 30(100%), 14(46.67%), 30(100%), 10(33.33%) and 18(60%) of the examined raw cow's milk, pasteurized milk, small scale ice cream and large scale plain and flavored yoghurt samples, respectively with mean values of 7.5×105± 3.9×105, 8.25×102± 5.04×102, 8.2×104± 4.1×104, 4.83×102 ± 3.15×102 and 2.72×103± 9.5 ×102 cfu/ml or g.
Higher results of total coliforms in raw cow's milk were reported by El-Zubeir and Ahmed (2007), while lower results were reported by El-Kholy et al. (2015). Higher results of total coliforms in pasteurized milk were obtained by Stanescu et al. (1992), while lower results were noticed bySiva et al. (1993). Higher results of total coliforms in ice-cream were reported byÇinar (2010), while lower results were revealed byEl-Kholy et al. (2015).
Lower results of total coliforms inplainyoghurt were detected byMoustafa (2004) and Sadik (2009), while higher results were reported by Ibrah | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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