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Study on the Quality of Market Dahi Compared to Laboratory Made Dahi

A. L. Shekh
Department of Dairy Science, Bangladesh Agricultural University, Mymensingh-2202, Bangladesh.

A. Wadud
Department of Dairy Science, Bangladesh Agricultural University, Mymensingh-2202, Bangladesh.

M. A. Islam
Department of Dairy Science, Bangladesh Agricultural University, Mymensingh-2202, Bangladesh.

S. M. E. Rahman
Division of Food Science and Biotechnology, Kangwon National University, Chuncheon, South Korea.

M. M. Sarkar
Bangladesh Livestock Research Institute, Savar, Dhaka.

Tian Ding
Division of Food Science and Biotechnology, Kangwon National University, Chuncheon, South Korea.

Jae-Ho Choi
Division of Food Science and Biotechnology, Kangwon National University, Chuncheon, South Korea.

Deog-Hwan Oh
Division of Food Science and Biotechnology, Kangwon National University, Chuncheon, South Korea.

Abstract/ Executive Summary:

Dahi is yoghurt like fermented dairy products available in Bangladesh made by traditional ways from raw milk. The aim of the present study was to check and compare the present quality status of the market dahi in reference to laboratory made dahi. For this, dahi was prepared in the laboratory (A) and collected from Kishoregonj district (B), Gazipur district (C), Bogra district (D) and Dhaka district (E and F). Consumer acceptance quality was judged on 100 point by a judge panel and chemical and microbiological quality test were done by established methods. ‘A’ type dahi was superior followed by E, D, F, B and C considering the consumer acceptance quality parameter. From chemical test, it appears that, B possess the lowest pH (3.75 ± 0.05) and highest was in C (4.46 ± 0.15). Total solids content of F type dahi (318.40 ± 4.44 g/kg) was highest and fat (52.00 ± 2.00 g/kg), protein (44.33 ± 2.00 g/kg) and ash (10.76 ± 0.31 g/kg) content were also higher in F type dahi. E and A type dahi were also with considerable figure in chemical quality parameter. Dahi B was inferior in respect of microbiological quality- total viable count (TVC) (× 10⁵ cfu/ml) content was 94.00 ± 4.58, yeast (cfu/ml) content was 183.33 ± 15.28 and mold (cfu/ml) content was 53.33 ± 15.28. The TVC (× 10⁵ cfu/ml), yeast (cfu/ml) and mold (cfu/ml) content of A type dahi were 39.67 ± 4.51, 50.00 ± 10.00 and 20.00 ± 10.00, respectively. Considering all the three major quality aspects dahi A was superior than others followed by F, D, E, C and B.

Keywords: Physico-chemical, Microbial quality, Dahi

Location: Dairy Chemistry and Technology Laboratory and Dairy Microbiology Laboratory of Department of Dairy Science, Bangladesh Agricultural University, Mymensingh.

Start Date:

End Date:

Program Area: Quality and Nutrition

Commodity: Curd

Objectives:

1. To check and compare the present quality status of the market dahi in reference to laboratory made dahi.

2. To check and compare their quality with the dahi prepared from fresh raw milk by following a standard procedure.

Methodology:

This experiment was conducted at the Dairy Chemistry and Technology Laboratory and Dairy Microbiology Laboratory of Department of Dairy Science, Bangladesh Agricultural University, Mymensingh. For the preparation of dahi in the laboratory (A) raw milk was collected from the BAU Dairy Farm. Milk was heated to boil on an electric heater and during the course of boiling; the volume of milk was reduced by 15-20% (approximately). Sugar was added during boiling @12%. After boiling, milk was kept off heat to bring the temperature near about 40- 45^oC. At this temperature, 2% mixed market culture was added to the milk and it was mixed thoroughly. Then the milk was poured in several plastic cups and the cups were placed in an incubator at 37^oC for incubation. After complete coagulation dahi was prepared and was kept in a refrigerator until analyzed. The collected market dahi samples were Aftab dahi (B) from Kishoreganj District, Aarong dahi (C) from Gazipur District, Mahram dahi (D) from Bogra District, Bikrampur dahi (E) and Maranchad dahi (F) from Dhaka District. From the collection to analysis, cold chain was maintained for all the samples. The laboratory made dahi and all the collected market dahi were subjected to the consumer acceptance quality- Smell and taste, Body and consistency and Color and texture, chemical quality- pH, Total solids%, Fat%, Protein% and Ash% and microbiological quality test- Total viable count cfu/ml, Yeast and mold count cfu/ml. Consumer acceptance quality was judged by an expert panel of judges of Department of Dairy Science using a 100 point score card. pH was measured by a pH meter, total solids by oven drying, fat by Babcock, protein by Kjeldahl and ash by incineration method. Microbial parameters (viable bacteria, yeast and mold counts) were determined by the standard plate count method according to APHA⁴⁾. Plate count agar and potato dextrose agar were used for viable bacteria count, yeast and mold counts, respectively. Plate count agar and sterile saline were prepared. The samples (1 ml) were transferred into sterile saline, and each serial dilutions, then put into plate and poured agar (10-15 ml) and allowed for solidification. After solidified, the plates were incubated at 32^oC for 48 hrs. The colonies were enumerated which plate having within 30-300 colonies. Potato dextrose agar was also prepared, and adjusted to pH 3.5 by adding 10% tartaric acid solution. Serial dilutions and agar pouring method were followed the same procedure of plate count agar. Plates were kept at room temperature (25^oC) for 3-5 days. The molds and yeast colonies were enumerated. The data obtained, were analyzed in Completely Randomized Design (CRD) by MSTAT computer package and incase of significant difference mean separation was done by LSD value.

Source of Information: Journal of Food Hygiene and Safety Vol. 24, No. 4, pp. 318~323 (2009)

Article Link (Online Journal):

Funding Source:

Budget:

Total Budget (Tk.) :

Achievement/Findings:

Considering the three major quality aspects (consumer acceptance, chemical and microbiological) laboratory made dahi was superior than market dahi. The findings of this study are expected to contribute to the production of good quality dahi.

Knowledge Management: Journal