Processes can bring ‘new’ hydrocolloids, Leatherhead

By Jess Halliday

- Last updated on GMT

Related tags Guar gum Edible thickening agents

Leatherhead Food International has completed a three-year research project that aimed to improve the performance of hydrocolloids using physical processing – methodology likely to be better-perceived by consumers in the natural-centric era.

The project, led by Dr Pretima Titoria, section manager for ingredients at Leatherhead, set out to see whether the properties of gelling agents could be improved by manipulating polysaccharide molecular weight by acidic hydrolysis.

In an article in Leatherhead’s internal publication LFIFoodNews (initially published in New Food Magazine), Dr Titoria described ‘first generation gelling agents’ as the likes of pectin, carrageenan, starches, alginates and gellans. Although very useful, such polysaccharide gels do have some limitations such as high melting point, and poor texture and flavour release. Their structure may also be impaired of they are stored for a long time.

While mixing these gels with other polysaccharide gels, like locust bean gum, guar gum and konjac gum, can help (yielding so-called ‘second-generation gelling agents’), Titoria and her team wanted to see whether texture and stability could be improved even further by physical processing.

She wrote that exploitation of processing technologies, as well as awareness of new technologies, to improve hydrocolloids’ performance can be quicker and cheaper than developing ‘brand new’ ingredients.

Moreover, consumers are veering away from ingredients with chemical or chemical-sounding names, providing a boost to those that use physical processes.

New and improved

Indeed Danisco is one ingredient firm that has made progress in improving on existing hydrocolloids.

Last September it received a positive safety call from EFSA on its partially depolymerised guar gum, which ​business director Kenneth Thoroe Hansen described as "a new hydrocolloid".​ He told that it can deliver more controllable, clean textures with no gumminess or off-taste.

The company is not considering the ingredient as a replacement for conventional guar gum per se, but as a complementary offering that brings new functionalities. It could, however, be used in place of some other hydrollocoids if is more cost effective.

Conventional guar gum is described as consisting "mainly of a high molecular weight hydrocolloidal polysaccharide composed of galactopyranose and mannopyranose units combined through glycosidic linkages, which may be described chemically as galactomannan".

The partially depolymerised guar gum is cut into smaller molecular weight sizes, and has different viscosity properties.

A taste of the findings

Dr Titoria told that the project was funded by members of Leatherhead Food International, and the full reports are available only to members.

However some elements of the experiments and results have been made public.

She said that the project was wholly experimental laboratory work. Over three years, the team looked at four different systems: agar; alginate–galactomannan; agar-galactomannan; and starch-galactomannan (with or without xanthan).

For each system they investigated the molecular weight distribution, rheology (flow/gelling characteristics) and texture properties, as well as some microscopy.

“The focus was looking at manipulation of molecular weight of some of these hydrocolloids, and looking at what would happen if these ‘manipulated’ hydrocolloids were mixed with other hydrocolloids in terms of texture and stability,” she said.

Amongst the findings, Titoria’s team saw that the combination of a hydrolised non-gelling agar fraction with a non-gelling galactomannan like locust bean gum produced a gelled network.

Agar that had been hydrolised for 16 hours had a break-load of around 70g, as opposed to 430g for non-hydrolised agar.

“One of the benefits is the softer textures which can break down easily in the mouth,”​ Titoria wrote.

The team also used microfluidisation, a form of high-pressure processing that uses high-pressure streams that “collide at ultra-high velocities in precisely-defined microchannels”.

This, they found, could bring new functionalities to the likes of starches, whey protein isolates, xanthans and carrageenans by controlling the degree of phase separation – thereby influencing rheological and textural properties.

“Molecular weight analysis indicated that microfluidisation brings about a mixture of depolymerisation and increase solubilisation to these gum solutions.”

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