Oral processing of meat: bolus characterisation and meat product design to match IDDSI guidelines for dysphagia management
Creators: name: Pematilleke, Nelum
Publisher: name: RMIT University
Year: 2024
Subjects: classificationCode: 300602
subject: Food chemistry and food sensory science
classificationCode: 321002
subject: Food properties (incl. characteristics and health benefits)
classificationCode: 400405
subject: Food engineering

description: Swallowing food is a complex process that needs sufficient mastication and incorporation of saliva to transport the bolus from the mouth to the pharynx. However, this process is not well coordinated in people that are suffering from dysphagia. Dysphagia sufferers often have difficulty or discomfort during the progression of the alimentary bolus from the mouth to the stomach. This may lead to choking or aspiration of food, and therefore, they are fed a texture modified diet to minimize these risks. However, inconsistencies of the texture and poor nutritional quality of those foods can affect the consumption, hence malnutrition and dehydration are common problems among dysphagia sufferers.

The mechanical (hardness, cohesiveness, adhesiveness) and the geometrical (particle size or shape) texture of the food are identified as the two key factors that drive choking risk. Therefore, this thesis investigated how these factors change during oral processing of healthy individuals and evaluated how this information could be useful in developing texture modified food for people with dysphagia, using beef semitendinosus muscles.

In the first stage of the study, the influence of cooking conditions on the modification of meat texture, and the relationship between instrumental and sensory texture profile were evaluated. This study helped to understand the initial bulk textural changes occurring during oral processing which relate to the first bite and initial transportation of food from front teeth to molar teeth. The meat was cooked at different temperature/time combinations and the instrumental and sensory texture profiles were measured and their correlation was studied. Results of the study revealed that cooking conditions had a significant impact on meat texture. Further, positive correlations between instrumental and sensory hardness, chewiness, and adhesiveness were also observed.

In the second stage of the study, different meat textures were studied to understand the changes that occur during oral processing and bolus formation, and how these relate to the geometrical (particle size) and the mechanical (hardness, cohesiveness, and adhesiveness) texture attributes. Meat with different initial texture profiles were given to healthy subjects and ready-to-swallow boluses were collected to evaluate mastication variables, saliva incorporation, geometrical and mechanical texture attributes. This study was conducted in two parts where the first part focused on particle size distribution (geometrical texture) and the second part focused more on bolus hardness, cohesiveness and adhesiveness (mechanical texture). Both studies showed the close relationship between the meat texture and bolus characteristics. Meat with harder texture created more bolus particles with smaller particle size and the bolus had higher hardness, adhesiveness and lower cohesiveness compared to boluses from softer meat. Significant (P &lt; 0.05) inter-subject variability was recorded for masticatory parameters and saliva incorporation however, mechanical, and geometrical characteristics of ready-to-swallow meat bolus did not vary among the subjects.
The third stage of the study examined the effect of hydrocolloid addition on the texture modification of meat. Beef patties were created with different hydrocolloids in 1 % (w/w) concentration and the possible hydrocolloids that have the ability to create soft &amp; bite-sized (dysphagia level 6) meat product, were screened based on the International Dysphagia Diet Standardization Initiative (IDDSI) recommended fork pressure test and instrumental methods. Results showed that two hydrocolloids (xanthan gum and CMC) added beef patties were suitable as soft &amp; bite-sized meat products. However, the structure and colour of the patties were not as desired therefore a combination of two hydrocolloids was recommended.

The standard IDDSI fork pressure test used in the previous study was based on an operator's observation making it difficult to analyse statistically. Further, the IDDSI test does not have adequate explanations on some factors, which may have an impact on the final observation. Therefore, another study was designed to provide a numerical value and explanation to IDDSI observations with the use of instrumental texture profile analysis. The newly developed test broadly explained the factors that can influence the results obtained from the IDDSI test such as test speed, rest time and fork position on the sample.

The results of the hydrocolloid screening study showed that a combination of two hydrocolloids could be able to create a soft &amp; bite-sized meat product with acceptable quality. Based on this observation, the beef patty was produced by combining two hydrocolloids (CMC and TST) which possessed soft &amp; bite-sized meat product. The information on texture of the ready-to-swallow boluses of healthy individuals, obtained from an earlier stage of this thesis, was used as a guideline to develop dysphagia oriented beef patties with pre-chewed texture. Moreover, the alternative instrumental fork pressure test provided numerical comparison, which was used as an optimising criteria, in addition to the standard IDDSI test.

The outcomes of this thesis provide insights into the rational designing of texture modified meat products based on the meat texture and oral processing behaviour. In addition, this thesis developed an instrumental method to conduct the IDDSI fork pressure test in a more reliable manner.