Brahim Bchir

Physico-chemical properties and amino acid profiles of sap from Tunisian date palm

Date palm sap (Phoenix dactylifera L.), also known as “legmi”, is a fresh juice extracted from date palm trees. The present study aimed to elucidate the effects of collection time (at the beginning of the tapping period and after seven days of collection) on the amino acid profile and physico-chemical properties of date palm sap from both male and female trees. Dry matter, protein, amino acid, and sugar profiles were determined using the Kjeldahl method, High-Performance Liquid Chromatography (HPLC), and High-Performance Anion-Exchange Chromatography with Pulsed Amperometric Detection (HPAEC-PAD), respectively. Date palm sap from both male and female trees contained high levels of carbohydrates. HPLC analysis showed that this fraction was dominated by sucrose in the sap sample from female trees compared to that from male trees. Male date palm sap was noted to exhibit lower dry matter content than female date palm sap but higher protein, total polyphenol, ash, and amino acid contents. While the major essential amino acids in the sap from male trees consisted of valine and threonine, they were represented by lysine and phenylalanine in sap samples from female trees. Further, Sodium Dodecyl Sulfate Polyacrylamide Gel Electrophoresis (SDS-PAGE) analysis showed the presence of a proteinic band of 30 kDa only for the sap from male trees. Taken together, the sap from both male and female date palm trees had a number of properties that are highly valued by the functional food industry.

Effect of pear apple and date fibres incorporation on the physico-chemical, sensory, nutritional characteristics and the acceptability of cereal bars

Cereal bars are nutritious food composed of several ingredients including dry raw and agglutinative ingredients. The objective of this study was to evaluate the effect of pear apple and date fibres, from cooked fruit co-product, addition on the physico-chemical textural and sensory properties of cereal bars. First, five formulations containing an amount of 10% of co-products and commercial fibre, used as a reference, were elaborated and their physico-chemical composition was determined. Second, to determine the acceptability of consumer, apple fibre co-products were added (6, 10 and 14%). Products were evaluated for their texture using a texturometer and sensory characteristics using an acceptance test. Results showed that physico-chemical composition of cereal bars elaborated with co-products was slightly different compared to those elaborated with commercial fibre. All bars have low water activity levels (∼0.470) and interesting energy (300 kcal/100 g bar). External appearance revealed a darker colour (L*:∼42/a*:∼8/b*:∼20). There were no significant differences (P > 0.05) in texture values (hardness: 40.8 N; cohesiveness: 0.34; springiness: 0.60; chewiness: 8.30 N) between cereal bars prepared with pear co-product and wheat bran. Acceptance test confirms the formulation used for cereals bars and showed that incorporation of 10% of co-product produced cereal bars with the highest acceptability. Sensory characteristics revealed that appearance is the limiting factor for consumer acceptability, essentially for cereal bars containing pear co-product. Apple, pear and date co-products could be used successfully as a food ingredient to develop new formulations of cereal bars.