Livestock Research for Rural Development 24 (12) 2012 Guide for preparation of papers LRRD Newsletter

Citation of this paper

Impacts of technology adoption on the quality of milk from smallholder farms in Wolayta, Southern Ethiopia

R Nebiyu, F Beyene*, Y T Giorgis**, B Kassa and F Kass

Ethiopian Institute of Agricultural Research, Holeta Centre, P.O. Box 31, Holetta, Ethiopia
* Wollega University P.O. Box 395, Nekemt, Ethiopia.
** Hawassa University P.O. Box 05, Hawassa, Ethiopia.
rahel924@gmail.com

Abstract

A study was conducted to assess impacts of building smallholder milk producers’ technical and material capacity on microbial quality of raw milk. Thirty women were selected and trained on good hygienic practices of milk production and products handling. They were also given milk handling equipments made of stainless steel. Milk samples were taken before and after the training.

Training brought positive impact on hygienic milk and milk products production and handling. Udder washing practice was improved by 32 % and use of individual towel to dry the udder was practiced by 53%. The training made 60 % women to use salt solution as teat dipping solution after milking. Cleaning milk and milk products vessels using hot water with the herbs was improved by 63.6 % through the training. The average shelf-life of milk, buttermilk and cottage cheese (1.27, 1.36 and 5.73 days) was enhanced after the training to 2.17, 2.57 and 7.17 days respectively. The training improved the mean scores of taste, aroma and appearance of milk by 29.8, 27.7 and 23.9 % respectively. The mean total bacterial and coliform loads of milk were significantly reduced by 13.8 and 31.8 % respectively through the training. The percent total solid, solid not fat, fat, protein, lactose and ash contents of milk produced in the study area were 13.8, 8.95, 5.35, 3.24, 4.53 and 0.71 respectively. Scarcity of material resources, untargeted training and extension services as well as lack of access to credit were identified as the main constraints of milk and milk products production and handling practices. Therefore, empowering and capacitating the target group through training and improving handling of milk and milk products would increase the quality and thus marketability of milk and milk products in the study area. 

Key words: capacity building, milk handling


Introduction

Milk secreted from a healthy cow's udder is germ-free (O’Connor 1994), and contamination occurs during and after milking. With well-structured daily routines and awareness among the personnel, some are easier to control and improve the situation considerably than others. There are many factors that affect milk quality. Dirty udders and teats, milking and ancillary equipments, uncleanliness of milker, unhygienic milking environment, the water being used on the dairy farm and the general sanitation are the most important sources of contamination of milk (Giffel 2003). The components of milk and its physical and chemical properties provide a very favorable environment for the multiplication of microorganisms that are the common contaminants (O’Connor 1994). Their rapid growth, particularly at high ambient temperatures can cause marked deterioration, spoiling the milk for liquid consumption or process into milk products. This can be avoided by adopting the simple, basic rules of clean milk production (Lore et al 2006). 

The first step to set a high quality product with longer shelf life is to make sure that the production and handling is hygienic, which will result in fewer spoilage organisms in the products (Yilma and Faye 2006). In Ethiopia, various factors combine to compromise the hygienic quality of milk products: unhygienic production, handling, processing and marketing, absence of cooling system especially around the producers, prolonged transport time, as well as ineffectiveness of the regulatory systems and quality control structures (Lore et al 2006). The problem is compounded by local climatic conditions, where the high ambient temperature does not favor the preservation of the products in optimal conditions. In order to assure the quality and safety of milk and dairy products, the various stages in the milk value chain from production to consumption have to be under control. The management of the quality by risk analysis or identification of potential hazards linked to a product or a process (HACCP-type approach), must be applied along the whole supply chain (FAO/WHO). Critical key aspects with respect to milk and milk products are ensuring that raw materials are of the best quality, elimination of spoilage and pathogenic bacteria from raw milk and other raw materials by heat treatment, prevention of subsequent contamination, and growth limitation of undesirable microorganisms during storage prior to consumption. 

In Wolayta  area much of the dairy works are undertaken by women (Mekonnen 2006). The implication of women targeted training on handling practices is not addressed. In the area milk production materials and techniques are traditional, and innovative methods are limited. The level of milk and milk products quality in the area is not also studied and limited work is done to improve the production, processing and marketing dairy products. Products from different households vary with respect to quality and thus local market demand. Poor quality products as assessed by the buyer’s organoleptic tests may not fetch attractive market prices and put the producers in a weak bargaining position.   

To improve the handling of milk and milk products, assessment of the existing practices is crucial. Therefore, the aim of this study was to assess the traditional and improved milk and milk products handling practices at the smallholder farmers’ level as well as to determine the composition and microbial quality of milk from traditional practice and compare it with improved handling practices adopted through training for further technological intervention. Also the study explores the effect of training on smallholder dairy development and ways of addressing the target groups (women) with the required skill and knowledge.  


Material and methods

Site description 

The study was conducted in Wolayta Zone (Figure 1). It is one of the administrative zones in Southern Nations, Nationalities and Peoples Regional State (SNNPRS) of Ethiopia with an altitude range from 1000 to 2000 meters above sea level (CSA 2004). The rainfall varies from around 1200 mm per annum in the high-lands to around 750 mm in the low-lands. Wolayta is known for its milk and butter production.

Figure 1. Map of Southern Ethiopia indicating Wolayta District at the north eastern part.

Sampling procedures  

Thirty volunteer women farmers who own at least one milking cow were purposively selected to participate on the study. All the participants were given training for three days on hygienic milking, processing and product handling according to Lore et al (2006). They were also supplied with aluminum cans (both for milking and handling) and were closely monitored for handling practices twice a week for one month before and after receiving the training. Data were collected from each household regarding, the traditional and improved practices of milk handling and processing. Accordingly, the collected samples were evaluated for quality properties, so as to assess the impact of the training on the quality of milk produced in the study area. Afterwards comparisons were made within those farmers before training and after training, regarding parameters, which included milking practices (procedures), hygienic handling of milk and cleaning of milk vessels as well as raw milk quality and shelf life. 

Sample collection  

Triplicate raw milk samples were aseptically taken in three sterile sample bottles of 100 ml capacities each for microbiological, chemical and organoleptic analysis. Organoleptic tests were made on-farm, but for microbial and chemical analyses, samples from both sampling phases (pre- and post-training) were taken to Hawassa University dairy laboratory. All samples were kept in icebox until the time of analysis.

Sample analysis  
Microbiological tests 

Total bacterial counts: Appropriate decimal dilutions of samples were plated on Plate Count Agar (PCA) and incubated at 32oC for 24 hours. Dilutions were selected in order to get the total number of colonies on a plate was between 30 and 250 (Richardson 1985).

Coliform count: Enumeration of coliform bacteria was done after plating 0.1 ml of sample from appropriate dilutions on Violet Red Bile Lactose agar (VRBAL) and incubated at 35 0C for 48 hours. Pink colonies were counted consider as coliform (Richardson 1985).  

Chemical tests

Titratable acidity was determined using % lactic acid method (O’Mahony 1988). Total protein, milk fat, solids-not-fat (SNF) contents and specific gravity of the milk samples at 15 0C to 20 0C and a pH of above 6 were determined using a Lactichek milk composition analyzer. Total solid and ash of milk samples were determined using standard procedure (Richardson 1985). Lactose content of the milk was calculated by deducting the protein, fat and ash content of the milk from the total solid.  

Organoleptic tests  

Five women that primarily trained on the scoring procedure were assigned to judge the appearance, taste and aroma of the milk samples. The parameters were evaluated on a 1-5 scale (Hedonic scale), where five stands for the best and 1 for the least score.

Data analysis 

The quantitative and qualitative data collected during the monitoring work were summarized using descriptive statistics. Chemical composition, microbial count and sensory score data of raw milk produced before training and after training were analyzed using one between subject and one within-subject factor repeated measure ANOVA Model (SPSS 2004). Mean comparison using Tukey test was done for those variables whose F value was statistically significant at 5 % significance level. Total bacterial counts and coliform counts were log transformed before statistical analysis.  

The model used for the statistical test was:

         Yij = m  + (training) i +  eij  

Where, Yij = individual observations for chemical composition, bacteriological or organoleptic quality of raw milk

            m = Overall mean

            Training i = ith training effect (i = before and after training)

            eij =  random error term


Result and discussion

Milking and milk handling practices 

A higher proportion of women practiced hygienic milking procedure after provision of training than prior to the training (Table 1). Udder washing was adopted by 30% of the women milk producers. Similarly, most of the women began to use individual udder towels (53.3 %) and hand drying (36.7 %) than prior to the training (23.3 and 40 %, respectively). In particular, the practice of dipping teats in salt solution after milking have become a customary procedure in most households (60 %) after the training whereas, none of the households were aware of the benefits of this practice prior to the training. Teat dipping solution after milking remarkably reduces entry of microorganisms through teat openings and resultant infection of teats, which is a likely risk as teats stay open after milking and become susceptible to infection (Phillips 2000).  

Table 1. Hygienic practices during milking before and after provision of training in the study area (N=30)

Milking procedure

Before training

After training

Udder wash

63.3

93.3

Dry the udder using

 

 

        Individual towel

23.3

53.3

        Hand

40.0

36.7

        Any cloth

3.3

10.0

Clean body of milking cows

46.7

76.7

Using dusty bedding material

53.3

36.7

Using salt solution as teat dip

0.0

60.0

Using hot water for cleaning

26.7

80.0

After receiving the training, 80 % of the respondents were found to use hot water for washing milk vessels whereas traditionally, only few women were accustomed to use hot water (26.7 %) for washing milk vessels (Table 1). Using hot water to clean milk vessels helps to remove fat from the milk vessels that could be dumped in the fracture of the rough surface and would facilitate the multiplication of biofilm organisms, as traditional milk equipment are reported to be often porous and therefore a reservoir for many organisms and difficult to clean (O'Connor 1994). Biofilms present on the surface of milk processing equipment threaten the quality and safety of dairy products (Giffel 2003).  

Fermentation

The traditional milk processing system in the study area was based on fermented milk. Small amount of daily collection of fresh whole milk was added on to previously fermented milk each time until enough amounts was collected for churning. Fermentation occurs spontaneously when milk is kept at the high ambient temperature. As it was done traditionally, the average fermentation time in Wolayta was 1.43 days whereas this fermentation time was shortened to 0.96 days, since women began to use starter culture which was made by women on farm after they received the training (Table 2). Evidently, the fermentation time with starter culture was quite short because of the interaction effect of both starter culture and the high ambient temperature. Also using starter culture improved the flavor of the milk products especially that of buttermilk. However, women preferred to use starter culture during the rainy season when the ambient temperature becomes low.  

Milk products preservation and shelf life 

In Wolayta, women kept milk and buttermilk in a clean and smoked vessel with the plant additives. The respective average shelf life of milk, buttermilk and cottage cheese in the studied area were 1.27, 1.36 and 5.73 days under traditional systems of preservation customarily practiced in the area. Whereas after training and employing hygienic handling with additives the average shelf life of fresh milk, buttermilk and cottage cheese improved to 2.17, 2.57 and 7.17 days, respectively, at an ambient temperature which were considerably longer than that under the traditional practices used before the training (Table 2). The improvement of shelf life of the milk products might be due to the effect of additives coupled with better hygienic practices performed during milking, handling and processing of milk, which was adopted through training.  

Table 2. Average shelf life of fresh milk, buttermilk and cottage type cheese and fermentation time evaluated under traditional and improved practices in Wolayta area

Milk products

Traditional practices

(Before training N = 30)

Improved practices

(After training N = 30)

Mean S. E

Mean S. E

Fresh milk (days)

1.27 0. 08

2.17 0.13

Buttermilk (days)

1.36 0.12

2.57 0. 19

Cottage cheese (days)

5.73 0. 34

7.17 0. 45

Fermentation time (days)

1.43 a 0.10

0.96 b 0.01

Row means designated by different superscript letters are significantly different from each other at P < 0.05.

S.E = Standard Error   

N= number of respondents

Organoleptic quality of raw milk  

The mean scores given to the taste, aroma and appearance of whole milk produced after the training were 4.03, 3.97 and 4.02, respectively and these values were significantly higher (p<0.05) than that of the corresponding mean scores of 2.83, 2.87 and 3.06 given to whole milk before the training (Table 3). The high sensory score of milk after the training is due to improved practices in hygienic milking procedures, low contamination of milk by cows’ hair, dust particles and flies as well as the hygienic handling of milk and milk vessels adopted after training. Good overall hygiene will have a positive effect on the overall quality and the final price of the milk (De Laval 2001). 

Table 3. Sensory scores, pH and acidity (% lactic acid) of milk before and after provision of training in Wolayta

Parameters

Score

Before training (Mean S.E)

After training (Mean S.E)

Appearance

3.07 b 0.17

4.02 a 0.11

Aroma

2.87 b 0.20

3.97a 0.12

Taste  

2.83 b 0.19

4.03 a 0.11

pH

6.50b 0.03

6.60a   0.02

Acidity (% lactic acid)

0.22b 0.011

0.18a 0.004

NB: Rows means for each parameter designated by different superscript letters are significantly different from each other at P < 0.05. 

Microbial quality of raw milk  

The mean total microbial load of whole milk produced after the training under improved practice (6.47 log CFU/ml) was significantly lower (P < 0.05) than that of milk produced before the training using traditional method, which was 7.51 log CFU/ml (Figure 2). Similarly, Tola (2002) reported that the mean microbial load of 7.60 0.02 log CFU/ml in traditionally produced raw milk in east Wollega. In the traditional system, the status of cleanliness of milkers, the udder of the cow, milking environment and the milking equipment could be the main sources of initial milk contamination. All these factors might increase the microbial load of milk produced under the traditional practices. Generally the level of bacterial contamination in milk is determined by the quality of the hygiene during milking, temperature, and the storage period (DeLaval 2001). When using improved practice, milk was produced under hygienic conditions. Milking and handling equipment for fresh whole milk was aluminum cans which are easier to sanitize compared to traditionally used clay pots. These factors might have contributed to the low microbial load of the milk.

Figure 2. Mean total plate count and coliform count (log CFU/ml) of whole milk before and after the training in Wolayta (N=30).

The average values of coliform CFU/ml of whole milk were 4.03 and 2.75 (Figure 2) for milk produced under traditional and improved practices respectively, the difference was significant. The usual source of coliform is faecal contamination of the bedding or udder (Giffel 2003), and this could be a result of poor hygiene in the traditional system. 

In general, there was high degree of contamination in the traditional system of milk production and handling than in the improved system. Yilma and Faye (2006) reported higher coliform count in whole milk samples obtained from small-scale and large-scale farms as compared to samples taken from research center where hygienic procedures were strictly followed during production and processing.  

Acidity and pH of raw milk  

Acidity: The mean titratable acidity of whole milk from traditional and improved practices was 0.22 and 0.18 %, respectively (Table 3). There was a significant difference (P < 0.05) between the acidity of whole milk produced using traditional and improved practices. This might be due to the fast acid production by the high load of microbes in the milk from traditional system. Similar to the result of the current study Yilma and Faye (2006) reported lower titratable acidity of 0.21 % for milk produced in research center than small scale farm (i.e. 0.3 %), where improved practices of milking are practiced.   

pH: In the present study the mean pH values of milk from traditional and improved practices were 6.50 and 6.6, respectively (Table 3). The overall mean pH value of whole milk produced using improved method was significantly higher than that of milk produced using traditional method. Similar to that of acidity, the lower pH of traditionally produced whole milk could be due to rapid fermentation caused by high load of microbes from the unhygienic surrounding.  

Compositional quality of raw milk

The overall mean percent total solids (TS), solid-not-fat (SNF), milk fat, total proteins (TP), total carbohydrate (lactose) and ash contents of whole milk were 13.8, 8.95, 5.35, 3.24, 4.53 and 0.71, respectively. The gross composition of milk did not differ before and after the training (P>0.05).   


Conclusions


Acknowledgements

We sincerely thank Canadian International Development Agency (CIDA) Project for financing the study and Hawassa University for providing laboratory facilities and logistics. 


References

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Received 24 July 2012; Accepted 23 November 2012; Published 2 December 2012

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