Proximate Analysis of Food: Composition of Whole Milk Powder Analysis

This report provides an in-depth exploration of proximate analysis, a crucial method in food chemistry used to determine the quantitative composition of macronutrients in food. The report focuses on the application of proximate analysis to whole milk powder, detailing the principles and methods for determining moisture, protein, crude fat, and ash content. It discusses the advantages and disadvantages of proximate analysis, including its ease of use and limitations. The report also outlines the composition of whole milk powder, including the typical percentages of fat, moisture, lactose, ash, and protein. Furthermore, it explains the principles behind the determination of each component, including methods such as air-oven, Kjeldahl, Soxhlet, and dry ashing. The report concludes by referencing key sources in the field, providing a solid foundation for understanding the analysis of food products.

Running Head: INTRODUCTION TO PROXIMATE ANALYSIS OF FOOD 1
Introduction to Proximate Analysis of Food:
Food Products used in Whole Milk Powder
Student’s Name:
ID:
Institution:

Running Head: INTRODUCTION TO PROXIMATE ANALYSIS OF FOOD 2
Introduction
Proximate analysis is a method used in food chemistry for the quantitative determination
of composition of different macronutrients present in food materials (Hart, F. L., & Fisher, H. J.
2012). It can be used to provide a very broad classification of food components, to give
comparison between foods based on nutritive value as well as to ensure that products made by
food- manufacturing companies meet legal requirements and safety standards and also for quality
control. One of the greatest merits of proximate analysis is that it is easy and thus cheap to carry
out. Some of its disadvantages are that it is not always selective; ammonia is determined as
protein and that it cannot be used to directly to determine carbohydrate content (James, C. S.
(Ed.), 2013).
This analysis that was developed in 1860 by Henneberg and Stohmann in Germany. It
began with the quest for nutritional analysis during that period and since then it has
been continuously developed, modified and improved. It includes determinations of six
components that include moisture, protein, fat (ether extract), crude fibre and ash in food (Atasie
et.al, 2009). The other materials present in the food sample apart from the ones listed above are
all covered by Nitrogen-free extract (NFE). NSE is however not measured by proximate analysis
but is calculated by subtracting from moisture, protein, fat, fibre and ash from 100 (Ramzan et.al,
2011). Thus, NFE represents a rough estimate of all soluble carbohydrate (i.e., sugar and starch).
Whole milk powder is obtained by removal of water and fat from whole milk (liquid).
There is usually a small percentage of water and fats left in the whole milk powder. Usually, the
whole milk powder contains 26%-40% fat, 3%-5% moisture, about 35%-40% lactose, 4%-6%
ash, and 25%-28% protein (Whetstine et.al, 2007).

Running Head: INTRODUCTION TO PROXIMATE ANALYSIS OF FOOD 3
The aim of this experiment is to learn and understand the methods employed in
determination of the moisture, protein, crude fat and ash content of the whole; to experimentally
determine the percentage compositions of such constituents in foodstuffs as well as to learn the
principles of determination involved in such methods.
Principle for Determination
Determination of Moisture and Total Solids
The content of food moisture can be determined by a number of methods which vary in their
accuracy, cost, speed, sensitivity, specificity, ease of operation, etc. The choice of a method
depends on: the kind food being analyzed and its nature (whether easily oxidized or
decomposed), accuracy required, availability and cost of equipment, relative amount of moisture
in the food product and rapidity of determination. Some of the methods involved include air-
oven method, microwave analyser, freeze-drying, Karl-Fisher method, vacuum-oven drying,
distillation etc. However, this determination has limitations such as degradation of unsaturated
fats and loss of other volatiles (Odebunmi et.al, 2010).
Determination of Ash
Ash in a food product is termed as the inorganic residue that remains after organic matter is
totally burned. It measures of the total amount of minerals in food. Ash contents in fresh foods
barely above 5%, although some processed foods can have ash contents as high as 12%, e.g.,
dried beef. Some of the methods used in determination here are dry ashing, wet ashing,
microwave ashing, sample preparation etc.

Running Head: INTRODUCTION TO PROXIMATE ANALYSIS OF FOOD 4
Determination of Nitrogen and Crude Protein
The most common method employed here is Kjeldahl method also called crude protein
determination which involves determination of the total amount of reduced nitrogen present in
products of protein. It was devised by Johan Kjeldahl who found out that all protein contains
almost the same amount of nitrogen (16%). Therefore, we can determine crude protein by
analyzing nitrogen content, which is easier, and calculate crudeby multiplying protein by a
factor of 6.25. Other methods include enhanced Dumas method, titration method and other
methods that use UV-visible spectroscopy.
Determination of Crude Fat
Foodstuffs have soluble fats in them. Methods used to measure crude fat are either gravimetric
like Soxhlet and Mojonnier methods while others are volumetric such as Gerber and Babcock
methods. The method used in determination of crude fats is depended on the fat’s insolubility in
aqueous systems after it is released from the emulsified state or partition of the fat between an
organic solvent and aqueous solution.
Determination of Crude fibre and Carbohydrates
Carbohydrate that is contained in the food has two fractions, the crude fibre (CF) and the
nitrogen-free extract (NFE). To determine crude fibre, residual food from ether extracts is
subjected to a reaction of acid and concentrated alkali under a high temperature. The reaction
produces an organic residue that is called crude fibre. To determine the nitrogen-free extract, you
take sum of the moisture content, ash, crude protein, ether extract and crude fibre (expressed in
g/kg) is subtracted from 1000. The nitrogen-free extractives fraction is a heterogeneous mixture
of all those components not determined in the other fractions.

Running Head: INTRODUCTION TO PROXIMATE ANALYSIS OF FOOD 5
References
Hart, F. L., & Fisher, H. J. (2012). Modern food analysis. Springer Science & Business Media.
Atasie, V. N., Akinhanmi, T. F., & Ojiodu, C. C. (2009). Proximate analysis and physico-
chemical properties of groundnut (Arachis hypogaea L.). Pakistan Journal of
Nutrition, 8(2), 194-197.
James, C. S. (Ed.). (2013). Analytical chemistry of foods. Springer Science & Business Media.
Odebunmi, E. O., Oluwaniyi, O. O., & Bashiru, M. O. (2010). Comparative proximate analysis
of some food condiments. J. App. Sci. Res, 6(3), 272-274.
Ramzan, N., Ashraf, A., Naveed, S., & Malik, A. (2011). Simulation of hybrid biomass
gasification using Aspen plus: A comparative performance analysis for food, municipal
solid and poultry waste. Biomass and Bioenergy, 35(9), 3962-3969.
Whetstine, M. E. C., & Drake, M. (2007). The flavor and flavor stability of skim and whole milk
powders.