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Food product defects

Food product defects

Defective products are a serious damage for brand reputation, in particular when social networks amplify news and consumers can readily make their dissatisfaction public. When a defect is detected, it is very likely that the product is recalled and confidence of consumers thus declines. Different defects can also happen during the best managed process: it is important to discover the root of the problem in order to prevent their recurrence

visual of a pea that is wide open with a white background. The pea contains in the middle a red pea. It is a clear sign of food product defect.

In order to cover multiple causes of product defects (chemical or microbiological or physical contamination, packaging/products interactions or voluntary adulteration of foods…), Mérieux NutriSciences offers a group of expert scientists and wide method portfolio to identify the proper causeA single point of contact will guaranty you efficient solutions.

Foreign bodies

A typical defect in food or packaged food is a foreign particle.

Microscopy observation highlights the presence of hair, insects, bones, molds and fungi, crystallizations or sediments in liquid products, as well as microbiological contamination.

These investigations are microanalysis where usually the object to observe is little and present in very small quantities, so that it is not possible to perform traditional and routinary analyses to identify the problem.

Mérieux NutriSciences uses cutting-edge technology combined with the skills and the knowledge of its experts to deal with these issues.

The equipment we can count on for the observation of foreign particles is:

  • Optical microscopy
  • SEM (Scanning Electron Microscope)
  • EDS (Energy Dispersive Spectrometry)
  • FT-IR (Fourier Transform Infrared Spectrometry)

The optical microscopy is a rapid, inexpensive technique, that allows a first general evaluation of the sample. In most cases microscopy is non-destructive and can sometimes be sufficient to identify the foreign body – most of the times it depends on analyst’s experience- or allows the acquisition of useful information to decide whether microbiological analyses are needed.

The other techniques have high magnification and resolution power; FT-IR is very useful for qualitative identification and particularly useful for organic matrices, but also for several inorganic ones.

All these techniques are preservative (they do not alter the sample) and can be used on small samples and are often used in combination as complementary data can facilitate the identification of the foreign bodies. Depending on the information they provide, other complementary analyses (such as GC/MS, HPLC, ICP, etc.) can be planned, both on the foreign body and on food.


Off-flavors are unwanted or unpleasant flavors to taste or smell; they are considered as a big defect for a food product.

Mérieux NutriSciences performs organoleptic evaluations by sensory analysis performed by a panel of trained judges that evaluate the defects; these studies can be also supported by specific instrumental analytical tests, such as the screening of aromatizing/volatile compounds in food (raw materials and finished products) flavorings, fragrances, essential oils and on food packaging. The screening can be qualitative or semi-quantitative, by SPME-GC/MS.  

In particular, it is possible to detect:

  • flavoring substances which shall not be added to food according to the law;
  • residual solvents;
  • aliphatic aldehydes;
  • diluents in flavorings.

The choice of the method and of the equipment is always done with a case-by-case approach, and can be targeted or non-targeted.

When we have specific suspects about the cause of the problem, a targeted approach can be enough to get the solution, in a very time saving and inexpensive way. It is the analysis of the problem and the technician’s expertise that makes the difference.

For more multifaceted issues, Mérieux NutriSciences offers non-targeted screenings to detect possible non-volatile substances in food: new extraction technologies and High Resolution Mass Spectrometry are the key to deal with it.

In case of spoilage microorganisms, Mérieux NutriSciences can use a traditional plating and identification (Maldi-Tof,16S rRNA sequencing) as well as characterize complex ecology with Metabarcoding.

Texture and appearance change, anomalous color and stain

Rheological characteristics of food include color, appearance, viscosity, texture and the accidental unwanted changes on these properties are considered a food defect.

Mérieux NutriSciences studies and measures viscosity through Brookfield viscometer, capillary viscometer and rheometer.

Viscosity is tested on:

  • homogeneous food products in liquid form
  • in granules/powder after proper preparation steps, through dissolution procedures

Stains or discoloration in food can be further defects. Mérieux NutriSciences studies these phenomena through microbiological analyses but also combines chromatographic (GC/MS, HPLC) and spectrophotometric analyses.

Regarding microbiological testing, Mérieux NutriSciences has different approaches: microscopic observations, plate isolation and microbial identification with Maldi-Tof and 16S rRNA sequencing. Our expertise in Next Generation Sequencing and bioinformatic analyses also allows Metabarcoding 16S using targeted MetaSequencing.

Color is a fundamental property for food, and color defects cause complaints, although not necessarily compromising food safety. Mérieux NutriSciences studies appearance and color of several foods through image analysis.

The digital image analyzer produces high-resolution photos of products in standard and repeatable lighting conditions, in order to:

  • obtain a high-resolution image of the product
  • determine the color of the product (digital quantification of each pixel)
  • compare different products/batches
  • compare color stability during a shelf-life study

Texture makes food appetizing. Mérieux NutriSciences evaluates food texture by means of a texturometer, with dynamometric tests.

Depending on the characteristics of the product, we can perform compressive strength testperforation test (e.g. on apples), flexural strength test in 3 points (e.g. rusks), cutting and shearing test (e.g. pasta, even after cooking), TPA (texture profile analysis), which simulates chewing on “soft” products.

The instrument assesses product adhesivenesschewinessbreaking strength, chewing strength, etc.

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