Analysis of the Organic Acids of Orange Juice

Sinclair, Walton B.; Bartholomew, E. T.; Ramsey, R. C.

doi:10.1104/pp.20.1.3

Cited by 37 publications

(11 citation statements)

References 7 publications

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“…Because of its limited stability, ascorbic acid was quantified by the method described under 2.8 and is further discussed under 3.6. Citric and malic acid are generally known as the major organic acids found in orange juice and determine its acidity (Karadeníz, 2004;Sinclair, Bartholomew, & Ramsey, 1945). Their respective initial concentrations of 12.2 and 1.44 g/L fall within the range of average values for sweet oranges, reported in literature (Karadeníz, 2004;Saavedra, Garcia, & Barbas, 2000;Sinclair et al, 1945).…”

Section: Organic Acid Profilementioning

confidence: 79%

Comparing equivalent thermal, high pressure and pulsed electric field processes for mild pasteurization of orange juice

Vervoort

Plancken

Grauwet

et al. 2011

Innovative Food Science & Emerging Technologies

145

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Section: Organic Acid Profilementioning

confidence: 79%

Comparing equivalent thermal, high pressure and pulsed electric field processes for mild pasteurization of orange juice

Vervoort

Plancken

Grauwet

et al. 2011

Innovative Food Science & Emerging Technologies

145

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“…The methods of fruit sampling and the analytical procedures are the same as those used and described in similar studies on oranges and lemons (7,8,9). It is necessary to give only a brief listing of the procedures in this paper.…”

Section: Methodsmentioning

confidence: 99%

The Organic Acids of Grapefruit Juice

Sinclair

Eny²

1946

Plant Physiol.

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The total acidity of grapefruit juice is highly associated with the quality of the fruit. Many of the biochemical reactions occurring in the fruit during growth and maturity depend upon the concentrations of the various acid constituents that compose the total acidity. The rates and types of reactions in citrus fruits are highly correlated with the pH, which in turn is directly related to the free and combined acids in the juice. These factors, considered collectively as the buffer system of the fruit, are important in regulating the proper reaction in the juice. The present investigation, therefore, is concerned with the determination of the organic acid constituents in grapefruit juice and the amounts of each that exist in the free and combined forms. Certain relationships are also noted between the pH and the existing cations that are available for salt formation. Materials and methodsThe methods of fruit sampling and the analytical procedures are the same as those used and described in similar studies on oranges and lemons (7, 8, 9). It is necessary to give only a brief listing of the procedures in this paper. Total soluble solids in the juice were determined as sucrose, with a Brix hydrometer. Using the table of STEVENS and BAIER (10), the true soluble solids were obtained by making a correction for the percentage of acid in the sample. The free-acid content of the samples was titrated on an aliquot portion of the juice with standard NaOH, with phenolphthalein as indicator. The organic acid fraction was precipitated from 80 per cent. alcohol with lead acetate and separated from the filtrate by centrifuging. The precipitate was washed with alcohol, suspended in water, and freed of lead by passing H2S through the solution. The lead sulphide was filtered off and washed with water. The filtrate and washings were combined and diluted to a known volume. The citric and malic acids were determined simultaneously, on aliquot portions of this solution by the method of PUCHER, VICKERY, and WAKEMAN (6). The amount of organic acid in the combined form was estimated by determining the alkalinity of the ash from an aliquot of juice.

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“…Citric acid is the main acid in citrus fruits (8,9) and the amount in the fruit is influenced by K nutrition (11). Approximately twice as much malic as citric acid, however, is found in citrus foliage and oxalic acid as insoluble Ca-oxalate occurs in even greater concentrations than malic acid in citrus foliage (10).…”

mentioning

confidence: 99%