Soluble and Insoluble Dietary Fibre in Date Fruit Varieties: An Evaluation of Methods and Their Implications for Human Health

Abstract

Dietary fibre analysis is expensive due to its reliance on enzymes such as α-amylase, protease, and amyloglucosidase. This study investigated whether enzymes are essential in analysing insoluble, soluble, and total dietary fibre (IDF, SDF and TDF) contents in dry fruits with very low starch and protein contents. The IDF, SDF, and TDF were measured in date fruits using the enzymatic gravimetric method AOAC 991.43 in the ANKOM dietary fibre analyser, with and without enzymatic digestion. The study analysed six date fruit varieties with a range of texture profiles. Our results highlighted agreement between both methods in the measured IDF, SDF, and TDF values. TDF values in date fruit varieties varied considerably, from 5.67% g/100 g to 10.33% g/100 g. Results from both methods also indicate that IDF constituted the bulk of dietary fibre content in all date fruit varieties (77.8% to 91.6%), while the proportion of SDF was between 8.4% and 22.2%. This study confirms that dates are a rich source of dietary fibre, and can be a valuable functional ingredient in foods that reduce the risk of chronic diseases. The study confirmed that the inexpensive non-enzymatic technique is a viable substitute for the enzymatic method for analysing dietary fibre in dry fruits.