Sugars, organic acids, and phenolic acids of exotic seasonable tropical fruits

Abstract

PurposeThe purpose of this study was to characterise the physiochemical properties of selected exotic seasonal tropical fruits available in Singapore.Design/methodology/approachA total of 11 seasonal tropical fruits including cempedak, chiku, custard apple, jackfruit, longkong, mangosteen, red jambu, pearl jambu, rambutan, salak and starfruit were analyzed for their sugars, organic acids and free phenolic acids composition using liquid chromatographic methods. Total phenolic content (free and bound), total soluble solids and pH were determined using Folin‐Ciocalteu method, refractometer and pH meter, respectively.FindingsFructose, glucose and sucrose were the main sugars in all the fruits. Cempedak had the highest sucrose concentration, while custard apple had the highest content of fructose and glucose. Malic and citric acids were the major organic acids in most of the fruits, except for pearl jambu and red jambu where succinic acid was the dominant acid. The total phenolic content varied from 122.94 to 712.20 mg gallic acid equivalent (GAE)/kg fresh weight (FW). Ferulic (0.631 mg/kg) and sinapic acids (1.506 mg/kg) were the predominant free phenolic acids in custard apple, while caffeic acid was the main free phenolic acid in jackfruit, salak and starfruit.Originality/valueThe paper demonstrates that the physiochemical characteristics of the 11 tropical fruits varied markedly, which is responsible for the differential flavour and stability. The findings are useful for epidemiological research and predicting the degree of ripeness, stability and post‐harvest processing required for these fruits.

Development of functional beverage from Sapodilla (Manilkara Zapota L.) fruit

“…Tasnim et al (2010) explained that total acidity of the juice will be influenced by the presence of a mixture of organic acid. The titratable acidity was calculated on the basis of citric acid because citric acid is the major organic acids in the sapodilla fruit (Lee et al, 2013). The titratable acidity of the sapodilla fruit was found to peak during its mature green stage (5.89%) and the lowest value was found during the overripe stage (4.95%) (Brito and Narain 2002).…”

“…Organic acids could originate from biochemical processes or microbiological activity and are found to be widely distributed in the fruits (Lee et al, 2013). The titratable acidity of the sapodilla differs throughout different stages of maturity, acidity was observed to decreases with an increase in ripeness (Pawar, 2011).…”

Local processing and nutritional composition of indigenous fruits: The case of monkey orange (Strychnos spp.) from Southern Africa

“…Fruit sweetness depends highly on sugar composition; (25) Sitrit et al (24) report accumulation of sugars and organic acids during ripening and sucrose conversion to glucose and fructose at the onset of ripening for S. spinosa. Total sugars were 28.2 g/100 g dw and the most abundant sugar was sucrose (12.9 g/100 g dw), a disaccharide, followed by the monosaccharides glucose (4.6 g/ 100 g dw) and fructose (1.9 g/100 g dw).…”

“…Organic acids in fruits originate from biochemical processes or from the activity of some microorganisms such as yeasts and bacteria. (25) The presence of organic acids (citric, malic and succinic acids) explains the acidic component that blends with sugars and results in the species characteristic blended acid-sweet taste. Sirit et al (24) found that S. spinosa contained malic acid 1.9 g/100 g dw, succinic acid 0.5 g/100 g dw and citric acid levels of 2.4 g/100 g dw.…”

“…(58,71) As previously alluded, thermal processing can lead to the release of bound phenolic compounds, hence the total phenolic content can be attributed to both free and bound polyphenolic compounds. (25) Thus, the retention or loss of phenolic compounds, nutrients and organoleptic characteristics during jam processing needs to be further investigated.…”