Effect of Okra Pectin on the Sensory, Physicochemical and Microbial Quality of Yoghurt

Abstract

The objective of this work was to investigate the effect of okra pectin from two genotypes (asha and agbagoma) on the physicochemical, sensory and microbial quality of yoghurt. Okra pectin concentrations (w/w pectin to milk powder ratios) of 0.2%, 0.4% and 0.6% were used in the yoghurt preparation and its water holding capacity, titratable acidity and pH were analyzed against a control (0.0% pectin) weekly for a month. Consumer acceptability tests for the yoghurt samples were carried out using 50 untrained panellists on a 7-point hedonic scale. Total aerobic microorganisms present in the most preferred samples were enumerated over a four-week period. Results indicated that samples containing 0.2% asha pectin were most preferred by panelists. Water holding capacity varied significantly with those containing asha pectin higher than agbagoma counterparts and the control. There was a decline in pH with increasing pectin concentration and over the storage period. Samples containing agbagoma pectin had lower pH (3.60 - 4.32) compared to samples containing asha pectin (4.22 - 4.45). Titratable acidity increased during the storage period and with increasing pectin concentration. After four weeks of storage at 4°C sample containing 0.2% agbagoma pectin had the least microbial count (7.6 × 105 ± 4.51 cfu/g), followed by the sample containing 0.2% asha pectin (2.4 × 107 ± 11.14 cfu/g) and the control (8.6 × 107 ± 5.57 cfu/g). The study revealed that addition of okra pectin at 0.2% improved the consumer acceptability of yoghurt and 0.2% agbagoma pectin inhibits the proliferation of aerobic microbes. Addition of okra pectin also improved the water holding capacity and reduced whey exudation.