Valorization of date palm (Phoenix dactylifera) fruit processing by-products and wastes using bioprocess technology - Review

Tunisian date (Phoenix dactylifera L.) by-products: Characterization and potential effects on sensory, textural and antioxidant properties of dairy desserts

Three Tunisian date varieties, Deglet Nour, Kentichi and Allig, served to produce syrups and powders, which were then examined for their physico-chemical composition and antioxidant properties. Different proportions of these sweetening-like agents were incorporated to produce nine different formulations of dairy desserts, with lower amount of added sugars to avoid any artificial flavoring or coloring agents. Sensory and color evaluation data revealed that incorporating Deglet Nour and Kentichi syrup offers the most desirable formulation. Furthermore, syrup polysaccharides and fibers contribute to better maintain the final product texture. In addition, date by-products create a good source of natural thickening agents, involved in enhancing apparent viscosity and spontaneous exudation. Thanks to their high content in phenolic compounds, date by-products considerably improve antioxidant activities of the formulated desserts. Therefore, they could be valued as natural ingredients in the formulation of novel dairy products with high nutritional-properties.

Production of fungal chitosan from date wastes and its application as a biopreservative for minced meat

Raw and processed meat contaminated with pathogenic microorganisms is a continuing worldwide problem facing health and industry overseers. Fungal chitosan was extracted, purified and characterized from Aspergillus brasiliensis (niger) ATCC 16404 grown in date syrup (dips) and applied as a potential meat biopreservative. The main features of produced chitosan were a deacetylation degree of 81.3%, a molecular weight of 31,000Da, 96% solubility in 1% acetic acid solution and a harmonized IR-spectrum to standard commercial chitosan. The application of fungal chitosan, as a natural and safe biopreservative for minced meat, was conducted in comparison with potassium sorbate, as a commercial meat preservative. Treated meat samples with 0.02% chitosan was the least trials in microbial contents, i.e. total count, coliforms, β-glucuronidase-positive Escherichia coli, Enterobacteriaceae, yeasts and molds, Staphylococcus aureus and coagulase positive staphylococci. The antimicrobial activity of fungal chitosan was considerably greater than that of potassium sorbate or their combination at 0.01% from each. Sensory characteristics, e.g. color, odor and texture, of treated meat with chitosan, were higher than those of control and potassium sorbate treated samples. Fungal chitosan, however, could be recommended as a powerful, natural and eco-friendly alternative for meat preservation and overall quality maintenance.

Chamaerops humilis L. var. argentea André date palm seed oil: a potential dietetic plant product

Chamaerops humilis L. var. argentea André (C. humilis) date palm seeds are an underutilized source of vegetable oil, and no studies describing their physicochemical characteristics to indicate the potential uses of this seed or seed oil have been reported. The oil content of the seeds is about 10%, mainly composed of oleic acid (38.71%), lauric acid (21.27%), linoleic acid (15.15%), palmitic acid (9.96%), and stearic acid (7.17%). The tocol (tocopherols and tocotrienols) content is 74 mg/100 g, with δ-tocotrienol as the major contributor (31.91%), followed by α-tocotrienol (29.37%), γ-tocopherol (20.16%), and γ-tocotrienol (11.86%). Furthermore, this oil shows high thermal stability. The differential scanning calorimetery curves revealed that the melting and crystallization points are 9.33 °C and -15.23 °C, respectively.

Phytochemicals in date co-products and their antioxidant activity

The date agro-industry needs to find appropriate techniques to give value to their co-products. This study analyzes twelve intermediate food products (IFPs) from date co-products, Medjool and Confitera cv. at several ripening stages, blanched and unblanched, for their content in bioactive compounds (phenols, tannins, flavonoids, carotenoids and anthocyanins) and the antioxidant activity (AA). IFPs from the more unripe stages had the highest AA and phytochemicals content, mainly phenols, up to 1.4 g GAE/100 g, with high proportions of tannins. Flavonoids were found in high amounts, up to 874 mg RE/100 g. Among the AA are significant the antiradical efficiency (4.62 mM TE/100 g) and chelating activity (252 μM EDTA/100 g). Blanching was beneficial for Confitera IFPs. A positive correlation was found between phenols, tannins and flavonoids and the AA; and their content could be used as indicator of the AA. Date IFPs have potential use as an antioxidant functional ingredient.