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Histology for detecting gelling agents, thickeners & stabilisers in meat-based products

Moncalieri (TO) – Italy, 19th August 2020

The Laemmegroup Laboratory of Moncalieri (Italy) has been active in the field of histology since 2009. For about two years, the Laboratory has been providing food histology services for the compositional quality assessment of meat-based products – for instance, the detection of any residues deriving from previous food processing steps.

In addition to this analytical service, the laboratory has recently introduced a new method allowing to identify the presence of gelling agents, thickeners and stabilisers in meat-based products.

 

ⓘ Food additives listed in Regulation (EC) No 1333/2008, and falling within codes E400 and E500, are used in the food industry for their gelling, thickening and stabilising properties. From a chemical point of view, they are polysaccharides and are intentionally used as additives due to their ability to form a three-dimensional network that retains considerable amounts of water, hence improving the product’s consistency. The same additives are also utilised for their stabilising properties as a technological support in the production of flavourings for the meat industry. In this case, their presence in the end product is not indicated on the label.

 

The new histological method at Laemmegroup involves fixing the sample in formalin, dehydrating and embedding the sample in paraffin wax and the final process of microtome cutting into 4-5 µm sections. From each sample, 5 slides are made in order to sequentially perform 5 different colours to which different compositional elements are associated.

Below are a few pictures of real examples:

Roast chicken with carrageenan, markedly blue colour on a colourless background

 

Roast chicken with cellulose derivatives, pink colour on a green background representing proteins;

 

Cooked ham with starch, in black colour (left)
using Lugol’s solutionor pink colour (right) using PAS staining method

 

 

 

 

 

 

 

Cooked ham without polysaccharides, green colour representing connective tissue and muscle fibres, and white colour representing adipose tissue

 

This type of analysis is qualitative and the different possible measurands are indicated in Table 1. Those measurands can hardly be detected simultaneously if another analytical technique is used. This analysis does not provide the exact identification of a single specific substance. It indeed identifies, even in small traces, the presence of gelling agents, thickeners and stabilisers in meat-based products.

 

Table 1

POLYSACCHARIDES: GELLING AGENTS, THICKENERS AND STABILISERS
HYDROCOLLOIDS STARCHES
COO ACIDS SO3 ACIDS NEUTRAL
tragacanth E413 carrageenanE407 gum arabic E414
gum karaya E416 guar gum E412
pectins

[non-amidated pectins E440(i)/amidated pectins E440(ii)]
locust bean gum E410
xanthan gum E415 Tara gum E417
alginates

(alginic acid E400/sodium alginate E401/potassium alginate E402/ammonium alginate E403/calcium alginate E404; Propane-1‚2-diol alginate E405)

agar-agar E406
gellan gum E418
cellulose derivatives

 

The analysis is also helpful to verify the correspondence between the ingredients indicated on the label and the actual composition of the products, and to perform a qualitative evaluation of the product.

The Laemmegroup Laboratory is the first in Italy to carry out this type of analysis.

For more information on this topic, please contact Chiara Mulasso – cmulasso@laemmegroup.it

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About Laemmegroup S.r.l.:

Laemmegroup is a service company that operates laboratories specialised in the analysis of foodstuffs, animal feed, and water destined for human consumption. Through the use of the most current technologies, we carry out analyses for all of the agri-food production industries.

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