Changes In Pectin Integrity During Mango Fruit Ripening and Thermal Processing

Abstract

Pectin gives structural strength to the primary cell wall and plays a key role in fruit and vegetable texture changes during ripening and  thermal processing. Understanding the degree and design of methoxylation is an important attribute in functional properties of pectin.  Two mango fruit varieties, Apple and Sabine at the unripe, intermediate and ripe stages were obtained from Makueni County, Kenya and  their Alcohol insoluble pectin (AIR) extracted and segmented into water soluble pectin (WSP), Chelator soluble pectin (CSP), Sodium  soluble pectin (SSP) and residue (cellullose and hemicellulose) fractions (HSP). AIR recovery rate for both thermally treated and untreated  samples recorded a yield of ≥95%. WSP yield (%) increased with ripening and thermal processing while SSP and CSP decreased  significantly (p≤0.05) with ripening and thermal processing. The HSP yield for Apple and Sabine at the unripe stage recorded  yields of ≥3.84%. Galacturonic acid increased significantly (p≤0.05) from unripe (16.16%) to ripe (28.72%) stage in WSP fraction, while it  decreased significantly (p≤0.05) in SSP with ripening in the two varieties. For neutral sugars, arabinose occurred most abundantly while  mannose was the least and both were significantly different (p≤0.05) across the maturity stages of the two varieties. The overall degree of esterification for the two mango varieties was ≥50%, thus on processing, products such as jam and other preserves, external pectin must  be added to form stable firm gels.