Abstract
Cloudy guava juice (CGJ) is one of the most popular rich sources of natural antioxidants, such as vitamin C (L-ascorbic acid, AA). The most challenging issue facing CGJ is the severe loss of antioxidants following the mitigation of cloud stability during juice processing or storage. The effects of food hydrocolloids, e.g. gum arabic (GA), pectin, and sodium carboxymethyl cellulose (CMC), and their binary combinations as natural additives in CGJs on the simultaneous development of cloud stability and AA preservation during juice processing and during 14 months of storage at 4 and 25 degrees C were firstly investigated. Among the studied hydrocolloids, the binary incorporation of GA (0.05 g/100 mL juice) and CMC (0.3 g/100 mL juice) showed the largest improvement in CGJ (G2C2 sample) quality. The cloud stability of the G2C2 sample was approximately 97%, which was 4.4 and 6.3 times higher than the control sample without hydrocolloids at 4 and 25 degrees C after 14 months of storage, respectively. Consequently, the G2C2 sample significantly inhibited AA degradation, and yielded an AA content of approximately 130 mg AA/100 mL juice, which was 2.6 and 6.6 times higher than control sample at 4 and 25 degrees C, respectively. Zeta-potential (zeta) and viscosity (eta) were used to investigate the potential effect of hydrocolloid combinations on the cloud stability. The G2C2 sample had a zeta potential of -31 mV and a viscosity of 17 cP providing better cloud stability when compared with other samples. The physicochemical properties of G2C2 sample were: pH, 4.2 +/- 0.5; total titratable acidity, 0.7 +/- 0.1 g citric acid/100 mL; degrees Brix, 9.5 +/- 0.1; % scavenging activity, 540.3 +/- 0.9 %; total phenolic compounds, 63.6 +/- 1.0 mg GAE/L; and colour coordinates, 70.8 +/- 0.6 L*, 0.5 +/- 0.1 a*, and 14.5 +/- 0.2 b*. Consumer acceptability of the G2C2 sample was also investigated, giving overall acceptability of more than 6.8 hedonic score without any deterioration in juice safety. The proposed simple hydrocolloids composite could increase the health benefits of cloudy juices. (C) All Rights Reserved