Joseph Hossenlopp

Fuzzy concepts applied to food product quality control: A review

Fuzzy logic is now a wide field of study and different tools have been developed over the last 10 years. Its implementation in food quality control for the food industry has been highlighted by several authors that have focused on different applications designed specifically for this task. This is especially true in the case of taking into account the reasoning process, expressed in linguistic terms, of operators and experts. Nevertheless, applications are still limited and few reviews on this topic are available. Consequently, the aim of this paper is to provide an overview of the application of fuzzy concepts to the control of the product quality in the food industry over the past 10 years. Future interesting developments and trends in this area are also emphasized.

Dry sausage ripening control integration of sensory-related properties

A feed-forward control algorithm is proposed to ensure the constancy of the sensory quality of the dry sausage during its fermentation. Fermentation is carried out with industrial equipment. The algorithm is based on human skill: the input variables of the controller are sensory evaluations made close to the line by the operators and the human diagnosis has been modeled using fuzzy logic. An experimental validation is introduced: the results show that the algorithm is likely to be able to control the process so as to obtain the desired sensory characteristics at the end of the fermentation stage. A user interface has been implemented in order to help the operator to cope with process control.

The fuzzy set theory: a helpful tool for the estimation of sensory properties of crusting sausage appearance by a single expert

Automation of visual assessment of foods is a desirable target in quality assurance. We propose an approach based on the theory of fuzzy sets to reproduce, with the help of a camera, the evaluation of sensory properties of a crusting sausage, made close to the manufacturing line (at-line), by a single expert evaluation: the operator. Our study is applied to the assessment of a sausage defect: the crusting. By means of a camera and an adapted image processing, the human evaluation of crusting is reproduced. Good results have been obtained from a database of 76 images.

A method for the analysis and control of sensory properties during processing––application to the dry sausage process

The sensory quality of a food comes from the combination of a set of parameters concerning all the steps of product life, from the raw materials to the conditions of preparation at home. We focus on manufacturing conditions and propose a method for the control of a set of sensory properties and defects whose variations must be kept within prescribed tolerances. This method entails, firstly, the identification of causes of variations of sensory quality, i.e., the definition of the scenarios leading to defects or faulty properties; secondly, the determination of control methods used by the factory, i.e., the corrective actions used to avoid or eliminate a defect or a deviation of a sensory property; and thirdly, the proposal of a strategy for improving sensory quality control. The method is illustrated by dry sausage manufacturing in two different factories. In both, the method enables proposing the improvement of sensory quality control, i.e., by a formal description of the skill concerning process control possessed by operators. A control system based on this formalized knowledge was implemented.

Formalization of at-line Human Evaluations to Monitor Product Changes during Processing: The Concept of Sensory Indicator

Sensory characteristics of food products are essential for consumers. It is a challenge for firms to maintain these characteristics constant, with as few variations in quality as possible. The control of quality properties and in particular sensory ones can be carried out using reliable process control strategies. Nevertheless, classical control approaches can rarely be used in food processes due in particular to the lack of real-time, reliable instrumental sensors, which limits available information on the product, and to poor understanding of the interactions between food and process. The scarcity of suitable on-line sensors is closely related to the variability of the raw material, the complexity of the biological phenomena during processing and the severe constraints that sensors must satisfy, such as hygiene, high humidity, and so on. As a consequence, some food product properties are very difficult to be quantified during food manufacture [11]. However, various solutions have been explored to overcome this problem: sensor design and adaptation, off-line measurements, software sensors [21]. Moreover, human evaluation is widely accepted as a tool for the evaluation of the quality of food products: operators play a major role in process control, since they take into account not only the information from sensors but also that from their own senses [20]. They can detect small changes in product characteristics such as cookie color after baking [12] thanks to their process knowledge and experience.