Characterization and discrimination of Indian propolis based on physico-chemical, techno-functional, thermal and textural properties: A multivariate approach

Objective: The present study assessed physico-chemical, techno-functional, thermal and textural characteristics of propolis samples (n = 30) collected from four Northern zones of India. Methods: The propolis samples were analyzed according to the Association of Official Analytical Chemists (AOAC) official protocols for their ash, moisture, and protein content. Soxtech, Fiber tech, Hunter LAB Colorimeter, TA.XT2i Texture Analyzer, Thermo gravimetric Analyzer, Discovery DSC 25 have been used to assess the crude fat, fibre content, colour, texture and thermal properties, respectively. Results and conclusions: Physico-chemical properties of propolis differed significantly (p < 0.05) and reportedthe highest balsam content (47.66%), protein (9.41%) and wax content (22.9%) in Punjab propolis (PP) where as the moisture content and water activity ranged from 4.89 to 7.37% and 0.73–0.81, respectively in propolis samples. Regarding techno-functional properties, PP had highest oil holding capacity (1.09–1.90 g/g), foaming capacity (11.08–17.03%), foam stability (67.3–75.43%), emulsifying activity (4.18–7.62%), and emulsion stability (3.24–4.77%). The positive a* and b* values of colour in this investigation indicated that the samples from all four zones lied in reddish yellowish areas of LAB colour space and relatively dull or gray as indicated by chroma values. Results of texture profile analysis demonstrated that all propolis samples were hard, cohesive, chewy and showed resilience. Differential scanning calorimetry predicted semi-crystalline behaviours of all samples. Three principal components, accounting for 98.95% variation were abstracted from fourteen physiochemical, seven techno-functional, seven textural and four thermal variables. Further, hierarchical cluster analysis successfully classified the propolis samples into four zones.