Capillary Gas Chromatographic Detection of Invert Sugar in Heated, Adulterated, and Adulterated and Heated Apple Juice Concentrates Employing the Equilibrium Method

• Published in: Journal of agricultural and food chemistry Vol. 47; no. 10; pp. 4261 - 4266
• Main Authors: Low, Nicholas H, McLaughlin, Michael, Hofsommer, Hans-Jurgen, Hammond, David A
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 01-10-1999
• Subjects: adulterated products; apple juice; Beverages - analysis; Biological and medical sciences; chemical analysis; Chromatography, Gas - methods; concentrates; Food industries; Food Inspection - methods; Fruit and vegetable industries; Fundamental and applied biological sciences. Psychology; gas chromatography; General aspects; heat treatment; Hot Temperature; Humans; invert sugar; Methods of analysis, processing and quality control, regulation, standards; oligosaccharides; Rosales - chemistry; Sweetening Agents - analysis; Sweetening Agents - isolation & purification; Capillary column; Heat treatment; Biochemical analysis; Fruit; Oligosaccharide; Invert sugar; Experimental study; Fruit juice; Gas chromatography; Apple; Analysis method; Heating; Authentication; Fingerprint method; Sweetener; Equilibrium method; Adulteration
• ISSN: 0021-8561; 1520-5118
• DOI: 10.1021/jf990457w

The equilibrium method is introduced for the detection of invert sugar addition to apple juice. The method consists of a pre-equilibration of the sample with dry pyridine at 50 °C for 20 min followed by the addition of trimethylsilylimidazole and heating at 75 °C for 40 min. The resulting derivatized carbohydrates are then analyzed by capillary gas chromatography. This method was successfully used by independent laboratories to distinguish heated pure, intentionally adulterated (with invert sugar), and intentionally adulterated and then heated apple juice concentrates. The equilibrium method was shown to give significantly lower coefficients of variation for this sample set when compared to the original capillary gas chromatographic method. In addition, these results indicate that it may also be an effective method for the detection of medium invert sugar, depending on the level of the fingerprint oligosaccharides in this sweetener. Keywords: Authenticity; apple juice; invert sugar