Rheological, microstructural and biochemical characterisation of fruit pomace jams

The present investigation aimed to develop and characterize fruit pomace jam prepared from different juice waste residues for rheological, morphological and biochemical properties. Five pomace jams were prepared viz. apple pomace jam (APJ), pineapple pomace jam (PPJ), guava pomace jam (GPJ), kinnow pomace jam (KPJ) and mixed fruit pomace jam (MFPJ). The dynamic oscillatory analysis revealed typical gel like behaviour for fruit pomace jams; storage modulus (G′) being higher than elastic modulus (G″) at variable frequencies. Surface morphology depicted heterogeneous ultrastructure with pocket formation in prepared pomace jams, among which best 3-D gel network was observed for KPJ. Highest values of color coordinates (L*, a* and b*) were also exhibited by KPJ. Dietary fibre content for GPJ was noted as 5.15 g/100 g which was highest in comparison to other pomace jams and commercial fruit jam. Maximum phenolic content was observed in MFPJ (292.02 mg GAE/100 g). Appreciable carotenoid content was observed in KPJ (5.36 mg/100 g) and MFPJ (3.81 mg/100 g). As per ABTS and FRAP assay, antioxidant potential of pomace jams exhibited the following trend GPJ > APJ > MFPJ > KPJ > PPJ for radical scavenging activity (%) and reducing power potential, respectively.