Science

Date palm: Eco-efficient and functional, claim researchers

18-Jun-2014 - By Nicola Cottam
Dates high in antioxidants but not sweet can be added to meats and highly sugared varieties used as a natural sweetener in dairy and pastry products, researchers say
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The natural sweetness and antioxidant properties of dates could add value to dairy, pastry and meat products, and would reduce waste of a fruit that was not being eaten fresh, Spanish researchers say.

Published in the journal of Food Chemistry, the researchers investigated the nutritional values of three different date pastes - intermediate food products (IFPs) - made using unblanched and blanced Khalal and unblanched Rutab.

The research was sparked by a need to use the country’s date crop better, they said.

In 2010, only 2.5% of Spain’s date harvest (100 tonnes) was sold as fresh fruit, the researchers said, due to low quality harvests in recent years. In addition, a high proportion of the fruit currently produced was not fit for direct consumption due to cracks and mould growth or was discarded for imperfections – blemishes or size, for example.

Finding an alternative outlet for wasteful co-products would be economically beneficial - to reduce disposal costs and increase efficiency, they said.

“The incorporation of these potentially functional ingredients obtained from co-products could be an economical strategy to introduce the date consumption into the Spanish population, but also to increase the eco-efficiency in the food industry,” they wrote.

“To optimize the use of these co-products in Spain and other countries with similar climatic conditions, the elaboration of intermediate food products adapted to the unripe and fresh dates may be a more feasible strategy without requiring a large industrial set up.”

Nutritional promise of dates

Dates contained high levels of natural sugars (including glucose and fructose) and were an important source of dietary fibre, vitamins and minerals, the researchers said. Although, sugar and nutritional content varied according to different ripening stages, they added.

Findings showed protein content decreased as the fruit ripened and was highest in the Rutab stage, when the fruit had less moisture and astringency, and a softer texture and darker colour.

Sugar content at this stage was high but phenolic antioxidant levels low. In contrast, dates at the Khalal stage of ripening were hard and juicy and contained a high quantity of phenolic compounds.

They said date pastes could clearly be exploited further in food additives.

“The incorporation of these IFPs into traditional Spanish products, such as meat products, dairy products, and pastries may open up new possibilities for the use of these agrofood co-products as added-value ingredients.”

In particular, the researchers said Rutab date past was suitable for use as a natural sweetener in dairy and pastry products, “among others”, because of its high sugar content. Khalal paste would be well-suited for meat products that needed antioxidant properties without a sweet taste.

“It would be recommendable blanching unripe fruits because improve their quality due to the inhibition of some enzymes and stabilizing the phenolic compounds and the colour, but also enhanced some technological properties such as the water holding capacity and the emulsion stability, which are very important to obtain desirable texture in some products,” they added.

Study process

The dates in the study were sourced from the Confitera cultivar in Alicante, Spain. Khalal and Rutab ripened dates were prepared according to their morphological characteristics.

The Khalal dates were divided into two groups, with the first treated in the same way as all Rutab samples (washed, peeled and pitted). The second Khalal batch was blanched in boiling water for three minutes and after cooling, were peeled and pitted. The fruit was peeled to delay skin browning.

Nutrient, antioxidant and sugar content were analysed and compared from the three samples.

 

Source: Food Chemistry
DOI: 10.1016/j.foodchem.2013.12.042
‘Characterization of novel intermediate food products from Spanish date palm (Phoenix dactylifera L., cv. Confitera) co-products for industrial use’

Authors: Ana Maria Martin-Sanchez, Sarra Cherif, Jose Vilella-Espla, Jamel Ben-Abda, Victor Kuri, Jose Angel Perez-Alvarez, Estrella Sayas-Barbera

Related topics: Science, Sweeteners (intense, bulk, polyols)