Physicothermal Properties of Basil (Ocimum basilicum L.) Seed Gum and κ-Carrageenan Mixed Gels

Goh, Jia Yeen (2016) Physicothermal Properties of Basil (Ocimum basilicum L.) Seed Gum and κ-Carrageenan Mixed Gels. Final Year Project (Bachelor), Tunku Abdul Rahman University College.

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Abstract

The crude extraction yield of Indian origin basil seed gum (BSG) was 12.45%. Intrinsic viscosity (56.37 dL/g) of BSG was investigated to characterize its molecular conformation and to yield estimation of molecular weight. The molecular weight was estimated to be greater than 2320 kDa and data suggested BSG as a flexible (KH = 0.42) linear anionic polysaccharide with random coil conformation (b = 1.29). Physicothermal properties of κ-carrageenan (KC)-BSG mixed gels, including colour and transparency, texture profile, syneresis, as well as gelatinization and retrogradation properties, were also studied. The colour change (ΔE) and transparency was significantly affected (p <0.05) with addition of BSG, however, the values remained fairly constant after 30% BSG for ΔE, and 40% BSG for transparency. Gel strength and rupture strength of the mixed gels were significantly reduced at 20% BSG, while the adhesiveness increased at 30% BSG. In contrast, gumminess, elasticity and cohesiveness of the mixed gels were affected at 10% BSG. A considerable reduction in syneresis was observed with 10% BSG (7.46%) as compared to the control (14.28%) and no obvious change was observed at 20% BSG (2.43%) or higher. Using the differential scanning calorimetry (DSC) technique, gelatinization temperature was observed to be lowest with inclusion of 30% BSG, where a shift of such temperature to lower degree by 15.44ᵒC was observed. Retrogradation properties showed improvement with increasing BSG concentration and it had a negative linear correlation (r = -0.8048) with degree of syneresis. These results suggested the suitability of BSG to reduce syneresis and gelatinization temperature of KC gels effectively at 20-30% concentration, with a compromise in slight difference in its textural profiles.