Abstract
Dysphagia is a difficulty in eating and swallowing of solid and/or liquid foods in elderly patients. Texture characterization of therapeutic diets for dysphagia patients has not been studied extensively. In this study, five different pureed therapeutic cakes (apple, orange, vanilla, carrot, and chocolate), previously proved efficient in the treatment of dysphagic patients, were evaluated for firmness, cohesiveness, adhesiveness, and springiness using textural profile analysis. The therapeutic cakes were tested at two serving temperatures: 12°C and 23°C. Results of sensorial tests confirmed that clinical efficiency and texture firmness of the therapeutic cakes ranged from 0.741 to 2.52 N for cakes at 12°C and from 0.608 to 2.58 N for cakes at 23°C. Similarly, cohesiveness ranged from 0.391 to 0.561 at 12°C and 0.479 to 0.568 at 23°C, adhesiveness from –0.219 to –0.436 N at 12°C and – 0.201 to –0.424 N at 23°C and finally springiness ranged from 46 to 70% at 12°C and 24 to 61% at 23°C. Non-therapeutic cakes averaged 2.77 N for firmness, 0.553 for cohesiveness, –0.385 N for adhesiveness, and 55% for springiness.
INTRODUCTION
Dysphagia, the inability to swallow, is a common condition that affects the elderly population.[Citation1] Swallowing is a complex action which is usually initiated voluntarily and is generally completed reflexively, whereby food is moved from the mouth through the pharynx and esophagus to the stomach.[Citation2] Swallowing is characterized by three different phases: the oral phase, the pharyngeal phase, and the eosophogal phase. The oral phase is also known as the preparatory-transport phase. In this phase, food is introduced into the mouth cavity and is subjected to mastication until a bolus is formed. The bolus is then thrust by the tongue into the pharynx. During the second or pharyngeal phase, the swallowing reflex is triggered, whereby breathing is stopped and peristaltic motion pushes the bolus downwards towards the eosophagus. During this last phase or the esophageal phase, breathing resumes, and the bolus proceeds downwards to the stomach, while the larynx and pharynx return to the resting status. Choking in dysphagic patients can occur in the first two phases. Dysphagia may be caused by neurological diseases, infections, metabolic diseases, or medical interventions.[Citation3] It is prevalent in almost 10% of the elderly population which translates into almost 400,000 Canadian patients and almost 60% of residents in long-term care institutions suffer from this condition.[Citation3,Citation4] The main risks associated with dysphagia are aspiration and choking, which in turn may cause patients to eat less for fear of choking. Over time, patients eating less suffer from malnutrition, dehydration, and this eventually leads to mortality. Following a preliminary screening, dysphagia can be evaluated by one of several methods: clinical bedside evaluation, endoscopy, manometry or videofluoroscopy.[Citation5,Citation6] With clinical bedside evaluation, observations are gathered by evaluating the patient's residual physical abilities.
In order to treat dysphagic patients, several approaches have been used at Sainte Anne's Hospital (SAH): changing the eating behavior of patients, swallowing therapy techniques, and modifying the diets. Until now, traditional modified texture diets served across hospitals, and health care institutions treating dysphagic patients have been to blend foods and serve immediately to the patient. Such foods are characterized as being unappealing, nutritionally diluted, and unrecognizable and have demonstrated no efficiency in treating dysphagia. However, the diet used at SAH consists of a varied menu of pureed and minced foods, raw and cooked, made up of meats (beef, chicken, ham, pork, lamb), vegetables (beans, carrots, broccoli, cauliflower, tomato etc.), fruits (peach, pear, etc.), cakes and sandwiches, and much more. What renders this diet more appealing than the traditional one is that foods are identical to their regular counterparts (in shape, size, and appearance) which both stimulates appetite and salivation among patients and encourages food intake. The modified texture diet foods offered at SAH are flavorful, nutritionally dense, and offer enough variety that allows for menu personalization for every individual. Most importantly, this diet is able to treat malnutrition secondary to dysphagia by texture adaptation dependent on the patient's condition. At SAH, dysphagia diets are texturally modified and are reshaped into molds to imitate the original substrate. Their clinical efficiency has been demonstrated in the nutritional treatment of dysphagia.[Citation7,Citation8] Re-shaping modified texture foods plays a very important psychological role in dysphagic diets since this enhanced attractive value of food presentation improves the pleasure of the eating event and the self-esteem of the client. This is highly desirable among elderly dysphagic patients since it stimulates their appetite.
Quantifying the necessary parameters for establishing the desired modified texture foods for dysphagic persons has come under intense scrutiny very recently. Few have attempted without much success to quantify the associated textural parameters of these foods, thus, creating a vacuum among health professionals.[Citation9,Citation10,Citation11] This vacuum has led each establishment to rely on its own evaluation system to characterize foods designed for dysphagic patients and to establish its own norms under which communication would be maintained uniform among the establishment's staff. In turn, this has created a multitude of similarly established designations, among different health establishments rendering the unification into one universally accepted system quite impossible. Indeed, diets and foods recommended for dysphagic persons are described qualitatively by various words such as smooth, soft, puree, minced, non-sticky, homogeneous, not dry, not hard, round, and so on. The universality of this empirical method leads to lack of continuity in care and lack of efficiency in the nutritional treatment of dysphagia. This situation leads to poor results and generally dysphagic persons lose weight and frequently develop undernutrition.[Citation3]
This research has been formulated to identify and measure the textural parameters of SAH's therapeutic foods for the purpose of quantifying these textural parameters. These foods are considered therapeutic because they are part of a nutritional treatment designed to clinically treat dysphagia. The textural profile analyses or TPA's associated with certain modified texture foods proven to be clinically efficient in the treatment of dysphagia, were necessary in order to establish a standard treatment based on valid scientific data and develop reliable and objective quality control methods for the production of these therapeutic foods. The specific objective of this study was to evaluate different SAH pureed, texturally modified and reshaped therapeutic cakes, used for the treatment of dysphagia, at two serving temperatures, 12°C and 23°C. Both quantitative and qualitative evaluations were involved in the study. Quantitative texture measurements were needed in order to obtain information concerning certain parameters such as firmness, cohesiveness, adhesiveness and springiness. Qualitative tests, involving sensory observations on the therapeutic cake samples, were linked to the quantitative textural attributes in order to validate the clinical findings of their efficacy as part of a therapeutic diet intended for dysphagic patients.
MATERIALS AND METHODS
Pureed Cake Formulations and Shaping
A database was established consisting of five different pureed therapeutic cakes: apple, orange, vanilla, carrot and chocolate. These cakes were specifically formulated, produced and reshaped as part of an integrated clinical approach for the treatment of patients suffering from dysphagia (). Samples were generally kept frozen 7−10 days prior to testing at −20°C. They were removed from the freezer and placed in a refrigerator to thaw 24 h prior to tasting and carrying out textural evaluation.
Figure 1 Standard cake preparation versus therapeutic pureed cake preparation.
Instrumental Texture Evaluation
A textural profile analysis (TPA) was made under each condition of testing to provide valuable information about the texture of a food product and gives some insight as to how it reacts to the pressure or force of a bite during eating. The TPA was measured simulating the mastication process by using a two-cycle compression test.[Citation12] A Universal Testing Machine (Lloyd Model LRX, Fareham, Hans, U.K.) was used for this purpose and textural attributes of firmness, cohesiveness, adhesiveness and springiness were evaluated. The machine was fitted with a 50 N load cell and the crosshead speed was set at 25 mm/min. All therapeutic cakes (apple, orange, vanilla, carrot, and chocolate) were tested. In addition to therapeutic cakes, regular apple, orange, vanilla, carrot, and chocolate cakes were tested to serve as controls.
Cake samples were cut into sample cubes of dimensions 3 cm × 3 cm × 2 cm size. R-control Data Analysis Software (Version 3.2, 1995) gathered the desired textural data using a personalized program. Measurements were made on ten samples of each therapeutic cake (replicated twice) at two serving temperatures of 12°C and 23°C (representing the range of temperatures at which these food products will be consumed by the patients depending on regular tray time delivery and time needed for completion of main meal) whereas regular cakes were tested only at room temperature (23°C). It is important to test at these two extreme temperatures in order to ensure that the product remains safe from a textural point of view for a dysphagic person.
A schematic of the force deformation curve is shown in from which the texture parameters (firmness, cohesiveness, adhesiveness and springiness) were derived as indicators of the textural properties for each cake. Firmness, cohesiveness, adhesiveness and springiness serve as basic essential quantifiers of texture directly related to the swallowing process and are defined as follows.[Citation12]: 1) Firmness (hardness) is the peak force during compression () related to the force required to bite, to masticate and to compress the bolus with the tongue and to push it through the back of the mouth into the pharynx. 2) Cohesiveness represents the attractive forces required to hold together the components of the cake and plays a very important role in the shaping capabilities of holding food matter together necessary for molding. It is calculated as the ratio of the area (energy) of the force-deformation curve under the second compression (bite) divided by the area of the curve under first (bite) compression, approximated by areas of the two triangles around the peak force. 3) Adhesiveness represents the attractive forces between the food and the structures of the oral cavity. It is measured by the negative force as the compression plate is pulled away from the product after completing the first cycle. If the product is completely inert and non-sticky, the adhesiveness will be zero. On the other hand, when product has a sticky tendency, the adhesive property will resist the pulling back of the compression plate creating a negative pressure (). 4) Springiness affects the ability of the food sample to return to their original shapes after the compression under the influence of mastication and tongue compression against the hard palate. It is a computed as a percentage ratio of the recoverable area (or deformation) and total area (or deformation) during the first cycle compression test.
Figure 2 Texture profile analysis: force deformation curve schematic of a food sample showing a first and second compression.
Sensory Quality Evaluation
From a qualitative point of view, food samples were also evaluated by a clinical expert, thereby providing essential descriptions and ratings for each cake sample allowing us to compare/ link experimental quantitative values to the qualitative assessments. Such qualitative assessments were performed by evaluation sheets designed with a specific purpose of having a complete and comprehensive description for each cake item as pertaining to its textural feel in the mouth, its clinical efficacy, and other organoleptic factors. Food descriptors retained, included a) perceived aeration/softness, b) homogeneity or heterogeneity of particle size, c) cohesiveness, and d) adhesiveness. Furthermore, based on the results of the sensorial evaluation, cake samples were classified as being a) clinically excellent (perfect texture), b) acceptable (adequate texture), c) mediocre (texture can be enhanced with a sauce), or d) dangerous (texture highly unsuitable). Consequently, associations were deduced between the condition of a food product in the mouth and its quantitative values measured by the texture machine.
Statistical Analysis
Data were analyzed by analysis of variance (ANOVA) using SAS software (SAS Institute, Cary, NC). The significance levels used were p ≤ 0.05. Duncan's multiple range test was used to compare the differences in mean values between test variables among the different cakes for a selected temperature and texture and also for each cake independently at different textures and temperatures.
RESULTS AND DISCUSSION
A typical TPA curve for therapeutic apple cake at 12°C is shown in . Unlike the illustrative used for identifying the texture parameters, the actual curve appears to be somewhat less eventful. All texture parameters, firmness, cohesiveness, adhesiveness and springiness, could nevertheless be computed as detailed earlier. Data on the various parameters were compiled from the TPA for each therapeutic cake sample at both 12°C and 23°C serving temperatures. Mean values and their standard deviations in firmness, cohesiveness, adhesiveness and springiness for each of the therapeutic cake samples at 12°C and 23°C, as well as for their non-therapeutic regular counterparts tested at 23°C are summarized in
Table 1 Mean values (and standard deviations) for firmness of therapeutic cakes (12°C and 23°C) and non-therapeutic regular cakes at 23°C
Table 2 Mean values (and standard deviations) for cohesiveness of therapeutic cakes (12°C and 23°C) and non-therapeutic regular cakes at 23°C
Table 3 Mean values (and standard deviations) for adhesiveness of therapeutic cakes (12°C and 23°C) and non-therapeutic regular cakes at 23°C
Table 4 Mean values (and standard deviations) for springiness of therapeutic cakes (12°C and 23°C) and non-therapeutic regular cakes at 23°C
Figure 3 Typical TPA curve of pureed apple cake.
When analyzing the different instrumental textural parameters (firmness, cohesiveness, adhesiveness and springiness) of the tested therapeutic cake samples at both serving temperatures of 12°C and 23°C, we are ideally looking for lower values of firmness, adhesiveness, cohesiveness and springiness with the purpose of maximizing the ease at which such samples are consumed by the dysphagic patient. Results obtained showed that firmness () and springiness () were higher for the non-therapeutic regular cakes (tested at 23°C) as compared to the values obtained for the therapeutic cakes at 12°C or 23°C. Cohesiveness values were only slightly higher, but they were relatively more stable for both therapeutic and non-therapeutic cakes (). Adhesiveness varied a little but again overall remained somewhat higher for non-therapeutic regular cakes (). When comparing the therapeutic cakes tested at 12°C and 23°C, there was an overall significant difference (p < 0.05) with those tested at 12°C generally displaying higher values for most texture parameters as compared to those therapeutic cakes at 23°C. Specifically, firmness values for apple, vanilla and carrot therapeutic cakes at 12°C were higher than the firmness values recorded for therapeutic apple, vanilla and carrot cakes at 23°C (). Cohesiveness and adhesiveness values didn't vary much between the therapeutic cake groups and remained relatively stable. Springiness values exhibited differences between therapeutic cake samples at 12°C and 23°C demonstrating a high variability for both cake groups reaching a maximal value of 72% for therapeutic vanilla cake at 12°C ().
For reference purposes, regular (non-therapeutic) cakes were tested in order to illustrate the difference between normal cakes consumed by most versus the therapeutic cakes needed in dysphagic diets. As can be observed from and , regular cakes showed higher overall mean values for firmness (2.77N) () and springiness (55%) () than their therapeutic counterparts. Adhesiveness, on the other hand, was slightly lower at −0.39N, as compared to −0.29N and −0.30N for therapeutic cakes at 12°C and 23°C, respectively ().
Sensorial evaluations for each different therapeutic cake at both serving temperatures of 12°C and 23°C were grouped and tabulated according to the different food descriptors (aeration/softness, particle size, cohesiveness and adhesiveness) and these are illustrated in and , respectively. A clinical dietician, serving as clinical expert and based on the sensorial evaluations, was able to identify and classify the therapeutic cakes according to their ease of swallowing for dysphagic persons on pureed diets. From a sensorial point-of-view, the developed therapeutic cakes needed to be soft, aerated, cohesive enough to retain the shape of the sample and not adhesive in order to prevent sticking to the inner parts of the oral cavity and slowing its movement downward through the throat. Particle size is an indicator of the textural feel of the food particles on the tongue and the gustatory sensation it can enhance in many patients. According to sensorial evaluation results (), all the therapeutic cakes served at 12°C were aerated and soft, cohesive but not adhesive. Most exhibited heterogeneous particle sizes except for the apple, vanilla and chocolate. Therapeutic cakes served at 23°C, showed somewhat different results (); indeed, all were aerated and soft except for the orange cake. They all displayed adequate cohesiveness and most were non-adhesive excluding the orange and peach samples which seemed to adhere a little to the mouth and palate. Particle sizes were for the most part were rated as being mixed type, some appearing to be homogeneous and others heterogeneous, and were mostly unaffected by serving temperature.
Table 5 Results of the sensorial evaluations carried out on therapeutic cakes at 12°C serving temperature
Table 6 Results of the sensorial evaluations carried out on therapeutic cakes at 23°C serving temperature
When clinically evaluated by the tasting expert, cakes at 12°C appeared to all fall within the categories of either excellent (apple, orange, vanilla and chocolate) or acceptable (peach, banana and carrot) () despite the large range of firmness, adhesiveness, cohesiveness and springiness values recorded earlier. Similarly, therapeutic cakes at 23°C ranged from excellent (apple, vanilla, banana, and chocolate) to acceptable (peach and carrot) and mediocre (orange) (). Again, despite the relatively large variations in firmness and springiness, these therapeutic cakes appeared to be fit for dysphagic diets. A potential explanation for this phenomenon would be the presence of a heat sensitive binding agent in the therapeutic cake formulations. Certain gelling agents are very heat sensitive and melt almost immediately when placed in a warm environment such as the mouth. Furthermore, interactions with body fluids, namely saliva, help speed their breakdown and melting process. The TPA's, which were performed on therapeutic cakes at higher temperatures (23°C), generated lower springiness values due to a softening of the binder than at 12°C. However, both cakes (23°C and 12°C) were deemed by the clinical expert not to constitute any danger for consumption by dysphagic patients. Hence, the textural measurements carried out using the Lloyd machine at room temperature cannot adequately describe the sensorial textural parameters of the cakes in the mouth, possibly due to much warmer conditions that may prevail when the cake is placed in the mouth and during the mastication/swallowing process in the human body.
Table 7 Clinical evaluation of therapeutic cakes at two serving temperatures of 12°C and 23°C
Furthermore, we studied any existing correlations between the gathered quantitative data and the collected sensorial evaluations for selected therapeutic cakes at serving of 12°C and 23°C (). Positive correspondences were identified for the three parameters of firmness, cohesiveness and adhesiveness. This means that quantified measurements obtained from TPA readings for each of the parameters, yielded similar quantitative evaluations by the clinical expert. Previously, no such correlations had been established successfully. Similar correspondences for springiness could not be achieved due to the high fluctuations in its quantitative measures from reasonably low to very high extremes despite all cakes being clinically efficient for dysphagic patients.
Table 8 Correlation between quantitative measurements of texture profiles (TPA) and qualitative assessments by clinical experts for selected therapeutic cake samples at 12°C and 23°C
CONCLUSIONS
The necessity to harmonize communication among health professionals and to establish a standard treatment when referring to modified texture foods was the driving force behind this study. The ideal mix of textural attributes necessary to provide a “safe” food product for a dysphagic person is one with minimal firmness and springiness, adequate cohesiveness and no adhesiveness. It is highly recommended that texture measurements be done at ‘in-mouth’ environment when studying the therapeutic efficiency of modified texture foods for the treatment of dysphagia, particularly those whose texture properties are heat sensitive at about body temperature. This is especially true for the parameter of springiness for which a positive correspondence could not be established between its quantitative and qualitative measurements. Further research is needed to simulate the mouth environment for food while taking into account other physical factors such as temperature and humidity which are critical when discussing food breakdown for bolus preparation and transportation at the oral level.
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