Encapsulating flavours in proteins in order to protect it during food formulation, may be counter-productive if the protein reacts with the flavour, says a new American study.
Josephine Charve and Gary Reineccius from the University of Minnesota report that many flavour compounds, such as ketones and aldehydes may react with the protein encapsulator and produce a browning reaction that would have detrimental effects on the finished product.
Writing in the Journal of Agricultural and Food Chemistry, the Minnesota-based researchers report that the traditional encapsulating material gum arabic still performs best with respect flavour retention during spray drying and storage.
“Although there has been extensive research on the binding of flavour compounds with proteins,there is no mention in the literature, as far as we are aware, about the reactivity of proteins toward flavouring components during the storage of spray dried flavours”, explained Charve and Reineccius.
Encapsulation… in a nutshell
In order to fill this apparent knowledge gap, the researchers tested three proteins – sodium caseinate, whey and soy protein isolates – as alternative materials to the traditional materials of gum acacia and modified starch for flavour encapsulation by spray drying. The test flavours used were limonene and different aldehydes.
Spray drying, which is one of the industry’s core flavour encapsulation technologies, is said to create particle distribution that results in better flowability, less dusting and good stability.
Charve and Reineccius report that the highest flavour retention during drying was observed for gum acacia, with 94 per cent retention, followed by modified starch wiyh 88 per cent, and whey protein isolate, with 87 per cent.
Moreover, gum acacia came up tops for retention of the aldehydes during storage for 28 days, but it did not protect limonene against oxidation, they said.
On the other hand, the alternative protein materials limited limonene oxidation, said the researchers, with over 70 per cent retention of the flavour.
“A lot of flavour compounds contain carbonyl groups (e.g., ketones, and aldehydes) that can react with the amino groups of a protein initiating the Maillard reaction and resulting in brown pigments as well as flavour loss,” wrote the researchers.
And that is indeed what was observed for all the powders prepared with the proteins, said Charve and Reineccius. The worst offender was the whey protein isolate.
No non-enzymatic browning was observed occurred when the flavours were encapsulated with the traditional gum arabic and modified starch.
“Non-enzymatic browning has been extensively studied in food systems as it influences the final quality of a product in terms of colour, nutritional quality and flavour,” wrote the researchers.
Leaving the door open to proteins
The study doesn’t close the door on the use of proteins to encapsulate flavours. On the contrary, the researchers noted that use of proteins for flavour encapsulation depends on the flavour being encapsulated. “If the flavouring does not contain any carbonyl compounds, it could quite effectively be encapsulated in a protein matrix,” they added.
“Further research is needed to examine the reactivity of proteins with other chemical groups (e.g., saturated aldehydes, ketones, esters) during the storage of spray dried powders. Additionally, the sensory impact of using proteins as wall material needs to be examined since the release properties of the dried flavours in a final product can be modified through chemical interactions,” concluded Charve and Reineccius.
Source: Journal of Agricultural and Food Chemistry
Published online ahead of print, Article ASAP, doi: 10.1021/jf803365t
“Encapsulation Performance of Proteins and Traditional Materials for Spray Dried Flavors”
Authors: J. Charve, G.A. Reineccius