Analysis of sugars in fruit juices using high performance liquid chromatography

Abstract

Determination of sugars, especially in fruit juices, is very significant bearing in mind their nutritive importance and the increased demands in food control, especially for fractions of carbohydrates in fresh products. Home-made juices as 'functional food' are in the focus of scientific attention because of the expansion of industrial manufacturing of fruit juices and importance of monoand disaccharides stability for the products quality. In this work determination of content of basic sugars in fruit juices, by applying a high performance liquid chromatography (HPLC), was performed. Content of glucose, fructose and saccharose was analysed in currant, cherry, peach, apricot and strawberry juices as well as in home-made cherry and apricot syrups. Quantification was based on comparison of chromatograms of standard solutions of saccharose, glucose and fructose with our samples. With isocratic elution applied temperature was 90˚C, water as a mobile phase and column Nucleogel Sugar Ca, refractometric detection was applied. The obtained results showed that concentrations of gucose, fructose and saccharose vary in the range 3,149-38,405 g/100 mL, 1,931-30,851 g/100 mL and 0,670-6,072 g/100 mL, respectively. Concerntrations of glucose and fructose do not exhibit significant variations in juices however, they are ten times higher in syrups. In all samples, juices and syrups, concentrations of saccharose do not differ significantly, except for one syrup sample where much lower content could be explained with possible enzymatic decomposition.

Određivanje šećera u voćnim sokovima je veoma važno, imajući u vidu njihov nutritivni značaj, ali i povećane zahteve u kontroli hrane kada su u pitanju pojedine frakcije ugljenih hidrata u sveže pripremljenim proizvodima. S obzirom na to da postoji porast industrijske proizvodnje voćnih sokova i značaj stabilnosti monoi disaharida za kvalitet proizvoda, domaći sokovi, kao funkcionalna hrana, postaju sve značajniji. U ovom radu je analiziran sadržaj osnovnih šećera u voćnim sokovima i sirupima kućne izrade primenom visokoefikasne tečne hromatografije (HPLC). Analiziran je sadržaj glukoze, fruktoze i saharoze u sokovima od ribizle, višnje, breskve, kajsije i jagode, kao i u sirupima od višnje i kajsije. Određivanje se zasnivalo na poređenju hromatograma rastvora standarda šećera i naših uzoraka. Uz izokratsko eluiranje analiza je izvođena pri temperaturi od 90 ˚C. Sa vodom kao mobilnom fazom i kolonom Nucleogel Sugar Ca, primenjena je refraktometrijska detekcija. Analizom je pokazano da sadržaj glukoze, fruktoze i saharoze varira u rasponu 3,149-38,405 g/100 ml, 1,931-30,851 g/100 ml i 0,670-6,072 g/100 ml, respektivno. Sadržaj glukoze i fruktoze se ne razlikuje značajno između sokova, a u sirupima je za deset puta veći. Sadržaj saharoze takođe se ne razlikuje značajno među ispitivanim uzorcima, osim u jednom sirupu zbog najverovatnije enzimske razgradnje ovog šećera.