Lab butter

Introduction

Butter is a dairy product made by churning of cream, mostly from fresh cow’s milk, with the additional of salt (Bylund, 1995). Salt (Sodium Chloride) is used as flavoring and preservative as it inhibit the microbial growth. Salt content in butter is limited by legislation in some countries. For example, in Thailand, the maximum sodium chloride content in butter shall not exceed 4 percent of total butter weight (Thai Ministry of Public Health, 2001). Therefore, analytical methods are required to determine the salt content in butter product.
In this experiment, salt was extracted from the aqueous phase of known quantity butter. The following salt content determination was done by Mohr’s titration method with silver nitrate (AgNO3) in the presence of potassium chromate K2CrO4 indicator. The end-point was then spotted when the red silver chromate forms. The amount of salt in butter was obtained by calculation of the experimental result.

Method
1. Determination of the concentration of a standard sodium chloride solution

2. Determination of salt in butter

Experimental Result

Table 1: Standard Solution Preparation
Titration
Titre Volume (mL)
1
20
2
19
3
20

The average titre value = = 19.667 mL
The molarity of NaCl solution = MNaCl = MAgNO3VAgNO3/VNaCl = = 0.0492 M
The calculated concentration of NaCl
= MW of NaCl x Molarity of NaCl
= 58.44 g/mol x 0.0492 mol/L
= 2.87ถ g/L
Table 2: Determination of salt in butter - Titration
Titration
Titre Volume (mL)
1
6.3
2
6.2
3
6.2

The average titre value = = 6.233 mL
The molarity of NaCl extract solution = MNaCl = MAgNO3VAgNO3/VNaCl = = 0.0125 M
The amount of NaCl in 100mL extract = 0.0125mol/L x L x 58.44g/mol = 0.073 g
The weight of sample butter = 3.439 grams
The percentage of NaCl of sample butter = = 2.12 %

Discussion
Mostly, the salt (NaCl) content in butter is ranged from 0.03% to 1.8% and there is butter that contains more salt content, up to 3%,

References: Bylund, G. (1995). Butter and dairy spreads. In Dairy Processing Handbook (pp. 263-266). Lund: Tetra Pak Processing Systems AB. Kirk, R. S., & Sawyer, R. (1991). Pearson 's Composition and analysis of foods. Harlow: Longman Scientific & Technical. Thai Ministry of Public Health. (2001). Ministerial Regulation No.227. Retrieved from The Information Resource Center of Thai FDA: http://newsser.fda.moph.go.th/food/file/Laws/Notification%20of%20Ministry%20of%20PublicHealth/Law03P227.pdf Ward, R. E., & Carpenter, C. E. (2010). Precipitation Titration. In S. Nielsen, Food Analysis (4th ed., pp. 206-208). New York: Springer.