Hygeia Public Health 2020, 55(1): 36-40pl

Comparision of the quality of freshly squeezed and commercial grapefruit juices

Anna Pasternakiewicz ^1/, Karolina Michalik ^1/, Maria Tarapatskyy ^2/, Monika Tomczyk ^1/

1/ Zakład Chemii i Toksykologii Żywności, Kolegium Nauk Przyrodniczych, Uniwersytet Rzeszowski
2/ Katedra Bioenergetyki i Analizy Żywności, Kolegium Nauk Przyrodniczych, Uniwersytet Rzeszowski

Summary
Introduction. Fruit and vegetables are a group of food products that should be found in the human diet in the largest amounts. Often these products are replaced by something more convenient for the consumer such as juices.
Aim. The comparison of the content of vitamin C, polyphenols and sugar profile in grapefruit juices available on the market and those freshly squeezed from fruit.
Material and method. Four juices purchased in Rzeszow and three juices freshly squeezed from grapefruits with a different country of origin were analysed. Acidity and vitamin C levels were determined by the titration methods, polyphenol content by the colorimetric Folin-Ciocalteu method and the content of glucose, fructose and sucrose was determined by high-performance liquid chromatography.
Results. The acidity of commercial juices was 119% lower as compared to juices freshly squeezed from grapefruits. Freshly squeezed juices contained significantly higher (p<0.05) amounts of vitamin C (109%) in comparison with commercial juices. The level of polyphenols in fresh juices was higher as compared to commercial juices, however the differences were not significant. The content of each sugars (glucose, fructose and sucrose) in the studied juices was variable, but the total amount of sugars were similar.
Conclusion. Freshly squeezed grapefruit juices are a better source of antioxidants than commercial grapefruit juices.

Key words:  grapefruit juices, acidity, vitamin C, polyphenols, sugars