Quality Characteristics and Functional Properties of Paneer Fortified with Sesbania grandiflora Leaf Powder

Abstract

Sesbania grandiflora (Agathi) is a nutritionally and pharmacologically rich tropical legume tree whose leaves contain substantial quantities of phenolic acids, flavonoids, carotenoids, calcium, and iron. Despite their well-documented bioactivity, comprehensive multi-parameter characterisation of paneer fortified with S. grandiflora leaf powder has not previously been reported, representing the focus of the present study; paneer is the most widely consumed “acid–heat coagulated” dairy product across South Asia. The present study developed and characterised paneer fortified with S. grandiflora leaf powder at 0% (T1, control), 0.5% (T2), 1.0% (T3), and 1.5% (T4) and comprehensively evaluated the effects on proximate composition, pH, instrumental colour (CIE L*, a*, b*), total phenolic content (TPC), flavonoid content, antioxidant activity (phosphomolybdenum and DPPH methods), texture profile analysis (TPA), water activity (aw), HPLC-based phenolic profiling, “SDS PAGE” protein characterisation, microbiological quality, and sensory acceptability. Fortification significantly increased protein (19.00–22.00%), crude fibre (0.40–2.30%), ash (1.20–1.30%), TPC (2.18–5.82 mg GAE/g dw), flavonoid content (0.31–1.56 mg RE/g dw), and antioxidant activity (phosphomolybdenum assay: 0.03–0.16 mg AAE/g; p < 0.05) with increasing leaf powder levels, while fat and moisture declined proportionally. HPLC profiling identified quercetin and kaempferol as the dominant flavonoids in fortified treatments, with total quantified polyphenols reported at 3.35 mg/g dry weight in T4. TPA revealed that T3 achieved comparable hardness to T1 (58.3 vs. 62.1 N), while maintaining superior springiness (0.84) and cohesiveness (0.68). Water activity decreased significantly from 0.973 in T1 to 0.951 in T4, corroborating enhanced microbial stability. “SDS-PAGE” revealed additional protein bands (18–35 kDa) in fortified samples, consistent with a plant-protein contribution, although this does not by itself confirm structural integration into the casein matrix. Microbiological counts were significantly reduced in fortified treatments throughout a 9-day refrigerated storage period, with T3 remaining within acceptable limits (<6.0 log CFU/g TPC) throughout. Sensory evaluation identified T3 (1.0%) as the optimal formulation with the highest overall acceptability score (8.2/9). These findings establish S. grandiflora-fortified paneer as a promising functional dairy formulation with an improved nutritional and antioxidant profile, which may contribute to nutritional enrichment in South and Southeast Asian populations, pending further validation of bioavailability and health outcomes.