2009_Book_FoodChemistry

18.4 Analysis 857
18.4.1 Various Constituents
Since the composition of the raw materials varies
greatly, deviations from the standard can be recognized
only by collective changes in the concentration
of as many components as possible.
For orange juice, Table 18.41 shows that when
the guide values for certain components are exceeded
or fallen short of, information is provided
on the proportion of fruit, the use of expressed
residues, acidification, sweetening, and microbiological
spoilage.
Table 18.41. Guide values for orange juice
Quantity being measured/Component Mean Range of Guide value a Indicator b
variation
Specific gravity at 20/20 ◦ C 1.046 1.045–1.055 x 1.0450 1
Extract ( ◦ Brix) c 11.41 11.18–13.54 x 11.18 1
Soluble solids (g/L) 119.4 116.8–142.9 x 116.8 1
Titratable acids (pH 7.0)
calc. as tartaric acid (g/L) 9.5 8.0–12 x 8.0 1
Ethanol (g/L) −− −− o 3.0 3
Volatile acids
calc. as acetic acid (g/L) − − o 0.4 3
Lactic acid (g/L) − − o 0.5 3
L(+)-Ascorbic acid (mg/L) 350 − x 200 2
Peel oil (g/L) − − o 0.3 7
Glucose (g/L) 28 20 x 22 1
Fructose (g/L) 30 22 x 24 1
Ratio of glucose to fructose 0.92 0.85–1.0 o 1.0 5
Sucrose (g/L) 33 47 o 45 5
Sucrose (% of total sugar) − − o 50 5
Ash (g/L) 4.0 2.9–4.8 x 3.5 1
Sodium (mg/L) 14 − o 30 1
Potassium (mg/L) 1900 1400–2300 x 1700 1
Calcium (mg/L) 80 60–120 o 110 1
Magnesium (mg/L) 100 70–150 x 90 1
Chloride (mg/L) − − o 60 1
Nitrate (mg/L) − − o 10 1
Phosphate (mg/L) 460 350–600 x 400 1
Sulfate (mg/L) − − o 150 1
Citric acid (g/L) 9.4 7.6–11.5 x 8.0 4
Isocitric acid (mg/L) 90 65–130 x 70 4
Ratio of citric acid to isocitric acid d 105 80–130 o 130 4
L-Malic acid (g/L) 1.7 1.1–2.9 o 2.5 1
Prolin (mg/L) 800 450–1300 x 575 1
Formol value (0.1mol/L NaOH 20 15–26 x 18 1
per 100 mL) e
Flavonoid glycosides
calc. as hesperidin (mg/L) 800 500–1000 o 1000 6
Water soluble pectins calc. as
galacturonic acid anhydride (mg/L) 300 − o 500 6
a Minimal (x) maximal (o) guide value.
b Indicator for: 1 fruit content, 2 heat or oxidation damage, 3 microbiological spoilage, 4 acidification, 5 sweetening,
6 extract of expressed residue, 7 as 6 but aromatized with peel oil.
c 1 ◦ Brix = 1 g of extract in 100 g of solution.
d cf. 18.1.2.4.
e Formol titration: after the addition of formaldehyde to a solution of the sample at pH 8–9, the free amino acids
are determined by titration with sodium hydroxide solution.