LOGO To weight out a sample on an arbitrary moisture(AM)basis,use the following: apie6gt抛 %dmater型Xrair9dsayplaeg drymatte
LOGO To weight out a sample on an arbitrary moisture (AM) basis, use the following:
LOGO To obtain dry matter,subtract percentage of moisture from 100. If the moisture has been determined in two stages,air drying followed by oven drying,compute total moisture contents of sample as follows: 7t=A+100-9B 100 Where TM is the total moisture,A the moisture loss in air drying,and B the%moisture of air-dried sample as determined by oven drying
LOGO To obtain % dry matter, subtract percentage of moisture from 100. If the moisture has been determined in two stages, air drying followed by oven drying, compute total moisture contents of sample as follows: Where TM is the % total moisture, A the % moisture loss in air drying, and B the % moisture of air-dried sample as determined by oven drying
LOGO Tables,nomograms,and calculators are available to simplify calculations in expressing results on a given basis,or for weighing samples on a fixed moisture basis(e.g.,20%in dried fruit).In view of the very wide range in moisture contents in various foods, analytical results are often meaningless unless the basis of expressing the results is known. Expressing analytical results on an as-is basis is wrought with many difficulties.It is practically impossible to eliminate considerable desiccation of fresh plant material.In some instances,even if great pains are taken to reduce such losses,the results may still vary widely.For example,the moisture contents of leafy foods may vary by as much as 10%depending on the time of harvest(from early morning to late afternoon).Similarly,the moisture contents of bread crust and crumb change from the moment bread is removed from the oven as a result of moisture migration and evaporation. Absorption of water in baked or roasted low-moisture foods (crackers,coffee)is quite substantial.In most cases,storing air- dried foods in hermetically closed containers is least
LOGO Tables, nomograms, and calculators are available to simplify calculations in expressing results on a given basis, or for weighing samples on a fixed moisture basis (e.g., 20% in dried fruit). In view of the very wide range in moisture contents in various foods, analytical results are often meaningless unless the basis of expressing the results is known. Expressing analytical results on an as-is basis is wrought with many difficulties. It is practically impossible to eliminate considerable desiccation of fresh plant material. In some instances, even if great pains are taken to reduce such losses, the results may still vary widely. For example, the moisture contents of leafy foods may vary by as much as 10% depending on the time of harvest (from early morning to late afternoon). Similarly, the moisture contents of bread crust and crumb change from the moment bread is removed from the oven as a result of moisture migration and evaporation. Absorption of water in baked or roasted low-moisture foods (crackers, coffee) is quite substantial. In most cases, storing airdried foods in hermetically closed containers is least
LOGO troublesome.Once the moisture contents of such foods are determined,samples can be used for analyses over a reasonable period. The concentrations of major components are generally expressed on a percentage by weight or percentage by volume basis.For liquids and beverages,g per 100mL is often reported.Minor components are calculated as mg (or mcg)per kg or L;vitamins in mcg or international units per 100g or 100mL.Amuunts of spray residues are often reported in ppm(parts per million). In calculating the protein contents of a food,it is generally assumed the protein contains 16%nitrogen.To convert from organic nitrogen(generally determined by the Kjeldahl method;see Chapter 37)to protein,the factor of 6.25=100/16 is used.In specific foods known to contain different concentrations of nitrogen in the protein, other conversion factors are used(5.7 in cereals,6.38 in milk). Heidelbaugh et al.(1975)compared three methods for calculating the protein content of 68 foods:(1)multiplication of Kjeldahl nitrogen by 6.25;(2)multiplication of Kjeldahl nitrogen by factors ranging
LOGO troublesome. Once the moisture contents of such foods are determined, samples can be used for analyses over a reasonable period. The concentrations of major components are generally expressed on a percentage by weight or percentage by volume basis. For liquids and beverages, g per 100mL is often reported. Minor components are calculated as mg (or mcg) per kg or L; vitamins in mcg or international units per 100g or 100mL.Amuunts of spray residues are often reported in ppm (parts per million). In calculating the protein contents of a food, it is generally assumed the protein contains 16% nitrogen. To convert from organic nitrogen (generally determined by the Kjeldahl method; see Chapter 37) to protein, the factor of 6.25=100/16 is used. In specific foods known to contain different concentrations of nitrogen in the protein, other conversion factors are used (5.7 in cereals, 6.38 in milk). Heidelbaugh et al. (1975) compared three methods for calculating the protein content of 68 foods: (1) multiplication of Kjeldahl nitrogen by 6.25; (2) multiplication of Kjeldahl nitrogen by factors ranging
LOGO from 5.30 to 6.38 depending on the type of food;and(3)calculation on the basis of amino acid composition,determined by chemical analyses.Up to 40%differences in protein content were found depending on the calculation method.There were,however,only small differences in mixed diets representing typical menus. If a food contains a mixture of carbohydrates,the sugars and starch are often expressed as dextrose.In lipid analyses(free fatty acids or total lipid contents)calculations are based on the assumption that oleic acid is the predominant component.Organic acids are calculated as citric,malic,lactic,or acetic acid depending on the main acid in the fruit or vegetable. Mineral components can be expressed on an as-is basis or as of total ash.In either case the results can be calculated as elements or as the highest valency oxide of the element. Amino acid composition can be expressed in several ways:g amino acid per 100 g of sample,or per 100 g of protein,or per 100 g of amino acids.For the determination of molar distribution of amino acids in protein,g-mol of amino acid residue per 100 g-mol of amino
LOGO from 5.30 to 6.38 depending on the type of food; and (3) calculation on the basis of amino acid composition, determined by chemical analyses. Up to 40% differences in protein content were found depending on the calculation method. There were, however, only small differences in mixed diets representing typical menus. If a food contains a mixture of carbohydrates, the sugars and starch are often expressed as dextrose. In lipid analyses (free fatty acids or total lipid contents) calculations are based on the assumption that oleic acid is the predominant component. Organic acids are calculated as citric, malic, lactic, or acetic acid depending on the main acid in the fruit or vegetable. Mineral components can be expressed on an as-is basis or as % of total ash. In either case the results can be calculated as elements or as the highest valency oxide of the element. Amino acid composition can be expressed in several ways: g amino acid per 100 g of sample, or per 100 g of protein, or per 100 g of amino acids. For the determination of molar distribution of amino acids in protein, g-mol of amino acid residue per 100 g-mol of amino