Towards an approach to assess critical quality points (CQPs) in food production systems : a case study on French fries production

M. Ali

Research output: Thesisinternal PhD, WU


This thesis investigated how to develop an approach for the systematic and science based assessment of those points in food production systems that have a critical effect on quality; such points could be designated as critical quality points (CQPs). One of the fundamental objectives of quality control is to reduce variation in the final quality attributes, which makes it essential to understand causes of variation in these quality attributes. A so-called techno-managerial approach was applied as the research framework to study both technological and managerial aspects. French fries (FF) production chain was chosen as a case study, because of the many points in the French fries chain where variation in conditions can lead to substantial variation in the final quality. French fries production chain was analysed, a comprehensive literature analysis, to review causes of variation in the major quality attributes. It appeared not to be possible to firmly assign such control points, as a systematic approach appeared to be lacking to establish variation in the final quality attributes. Based on available quantitative data in literature, selection of suitable cultivar, time-temperature settings during bulk storage, blanching and final frying were indicated as potential sources of variation and can be considered critical to control final quality attributes. The conclusion of the study was that further quantitative insight was required in the contribution of variation in process and product factors to the actual variation in the profiles of major quality attributes of French fries.

Consequently, a study was conducted to getquantitative assessment of variation in texture and colour profiles of French fries as a function of various fixed time-temperature (t-T) frying settings. The study indicated that increased frying temperature and time (from 170 to 190 oC, and from 4 to 6 min) resulted not only in higher mean ln (peak force) values as a measure for texture and colour index, but also in a larger variation in peak data force from (29 %) and colour index data from (41 %). These results were more obvious in the case of thin as compared to thick FF. Therefore, results suggested t-T settings during final frying can be considered as critical to control final quality attributes of French fries.However, t-T blanching settings were not considered as critical to control final quality attributes of French fries because of the minor effect on variation, but selection of an optimum t-T blanching setting is to be considered as an important design activity while making process and product specifications because of the large effect on the actual value of a quality parameter.

The managerial part indicated that implementation of frying instructions, sharply reduced variation in ln (frying time) and ln (portion size). This reduction in variation ultimately resulted in significant reduction in variation (Cal Var) in the ln (Peak force) and colour index data of thin FF.

Finally themain findings were discussed to put them in a general perspective.First, it was discussed that the well-known HACCP approach is not suitable for establishing CQPs because quality attributes are multidimensional and multifactorial as compared to hazards. Nevertheless, the HACCP approach was taken as the starting point and based on these insights, a systematic approach to assess CQPs is proposed. The proposed approach has provided a basic procedure consisting of six global steps for the assessment of critical quality points in a food production system, based on our research on the production chain of French fries.  Each of these steps is discussed in detail with respect to the applicability to food chains. A general picture emerged but it is also clear that in some details further research is needed for specific food chains, Moreover, the TM (Techno-Managerial) approach applied in this thesis proved to be essential as well, as the case study clearly showed the interconnection between human and technological factors on variation in quality attributes. Whether or not this is also the case for other food chains remains to be established, but it is certainly a point to give attention to. This approach could be the base for further studies with different foods by investigating the production chain of other food products, to further evaluate and improve this approach as structured guidelines for the food industry to control and assure quality of the food products.

Original languageEnglish
QualificationDoctor of Philosophy
Awarding Institution
  • Wageningen University
  • van Boekel, Tiny, Promotor
  • Luning, Pieternel, Co-promotor
Award date27 Feb 2012
Place of Publication[S.l.
Print ISBNs9789461731920
Publication statusPublished - 2012


  • food quality
  • critical control points
  • quality controls
  • quality management
  • chips (french fries)

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