NUTR 3210 Lecture Notes - Lecture 2: Foregut Fermentation, Small Intestine, Mouth
27 Jun 2018
School
Department
Course
Professor
Learning outcomes:
Briefly describe the methodologies of Proximate Analysis and Southgate Analysis
Describe the characteristics of fiber
Describe digestion and digestibility
Describe the structure of a variety of digestive systems, including simple, ruminant and avian
Describe the indicator method of determining digestibility
Apply the indicatory method of digestibility to novel problems
Critically evaluate data regarding digestibility
Introduction:
Food composition analysis refers to the development, application and study of analytical
methods for characterizing foods and their constituents - it is a very important area in nutrition
studies
Methods that are used in the chemical analysis of foods and feeds:
oProximate analysis: basic determination of moisture, crude protein, crude fat, crude
fibre and ash
oNewer methods: replace or extend traditional components of proximate analysis
oSouthgate analysis: for crude fibre for modern CHO labelling
Why is it important to look at food composition?
There are several reasons to have standardized quantification of food nutrients:
oAllows food manufacturers to maintain quality control, to produce foods that are safe,
nutritious, and desirable
oAllows the consumer to make informed decisions about what they choose to eat
oIt is the basis of government regulated food labels, including nutrition facts, ingredient
list, and health claims
oIt is used to eliminate economic fraud. Used to provide evidence of food authenticity to
prevent misleading information
oIt is used to enable fair competition between companies. Helps to create standards of
identity of products
oIt is used in food science applications to develop new crop varieties and novel foods
oIt is the first step to understand the chemistry of nutrients
Nutrition facts label - general:
When foods are analyzed, we see that not all foods are created equal
Nutrient density is a very important concept that expresses the total amount of essential
nutrients in one serving of a food, relative to the energy content
The total amount of food that we eat each day is largely regulated by our energy requirements
Having data on food composition makes it easier to identify nutrient density and helps to
recognize differences among foods
Introduction to proximate analysis:
Developed in Germany during the 1800s, originally it was used to analyse animal feeds, and later
for human food analysis
find more resources at oneclass.com
find more resources at oneclass.com
Components of proximate analysis: moisture
Why is determining water content important?
oWater can make up a large proportion of the shipping weight and the price of foods sold
by weight
oWater is a major component of most fresh foods; drier foods may be less palatable
oHigh moisture content may cause foods to spoil, especially in warn environments
oWe cant do the other methods in this analysis until the sample is dried
Components of proximate analysis: ether extract
The ether extract contains the lipid-like substances in the sample. Ether is a non-polar solvent
that will carry out the lipids with it
The goal on this extraction is to determine the quantity of lipids in the food sample that have
nutritional importance. For example: the triglycerides, phospholipids, cholesterol, and fatty acids
With a basic extraction, there is no definition of subclasses of lipids and because of this further
analyses are needed by gas chromatography to quantify the relative amounts of various fatty acids
find more resources at oneclass.com
find more resources at oneclass.com
Knowing which lipids are present and in which amounts is important data from the consumer to
look at in a food label
Components of proximate analysis: ash
The residue that was left behind can be ignited by heating it to 500 - 600 C in order to combust
the organic molecules
oThe end result is an inorganic residue, or "ash", that contains most of the minerals in the
sample
Importance of ASH/ mineral analysis:
oUsed in nutritional labeling - the content of sodium, calcium, and iron is mandatory on
food labels
oHelps to determine the quality of many foods, including their taste, appearance, texture
and stability, as these depend on the concentration and type of minerals that food contains
oIndicates if foods have high mineral content, as this information is sometimes used to
determine the ability of foods to retard the growth of certain microorganisms
oIt assists in achieving optimal food processing: it is often important to know the mineral
content as this affects the physicochemical properties of food
Components of proximate analysis: nitrogen
Why is it important to measure crude protein?
oIt is useful in animal production, pet foods, baby formula, athletic supplements, etc.
oThe traditional method to obtain this value is the Kjeldahl method
Melamine elevates crude protein analysis - produces high nitrogen content
Components of proximate analysis: crude fibre
Why is it important to measure crude fibre?
oCrude fiber is organic matter that is indigestible and is used to add bulk to the feed
oThe amount of fiber is controlled by government agencies to prevent companies from
adding waste products in order to bulk up a feed
Southgate method
oThis method provides a separate quantification of sugars, starch and fiber. It does not
subdivide the fiber into soluble and insoluble fractions
oThis limits its use in agricultural settings, where the fermentability of the diet is a critical
component of its potential to meet energy requirements for different species
For human food labelling we need to differentiate between sugars, starches and fibre
Most of our foods are fairly well known in terms of chemical composition, and there are detailed
databases that are hooked into diet analysis software that provide information on the content of
all the essential nutrients and the types of fibers found in common foods
oThe databases are based on laboratory work done on known human foods
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Briefly describe the methodologies of proximate analysis and southgate analysis. Describe the structure of a variety of digestive systems, including simple, ruminant and avian. Describe the indicator method of determining digestibility. Apply the indicatory method of digestibility to novel problems. Food composition analysis refers to the development, application and study of analytical methods for characterizing foods and their constituents - it is a very important area in nutrition studies. Methods that are used in the chemical analysis of foods and feeds: o. Proximate analysis: basic determination of moisture, crude protein, crude fat, crude fibre and ash: newer methods: replace or extend traditional components of proximate analysis o. Southgate analysis: for crude fibre for modern cho labelling. It is the basis of government regulated food labels, including nutrition facts, ingredient list, and health claims o. Used to provide evidence of food authenticity to prevent misleading information o. It is used to enable fair competition between companies.
