Impact of pectin or xanthan addition to mashed potatoes gelled with κ-carrageenan on texture and rheology, oral processing behavior, bolus properties and in mouth starch digestibility

Oral processing behavior affects starch bioavailability, but the impact of the oral phase on starch digestibility in potato dishes enriched with polysaccharides has not been clearly established. Therefore, pectin (1 %) or xanthan (1 %) were added to mushed potatoes (MP), which was gelled with κ-carrageenan (0.6 %), to produce the samples named MP-CarP MP-CarX, and MP-Car, respectively. Rheological, textural, sensory and electromyographic tests were conducted on the samples, along with bolus analysis. Both pectin and xanthan softened MP by 23 and 30 %, respectively, and reduced gel strength. The MP-CarP and MP-CarX were orally processed for shorter chewing times; however, their boluses exhibited a 20 % increase in cohesiveness. Chewing the MP-CarP highly enhanced salivation, resulting in a 45 % increase in bolus fragmentation, while the MP-CarX had the highest cohesiveness and lowest fragmentation. The variations in oral processing of MP with pectin or xanthan resulted in differing levels of starch hydrolysis and glucose release in the mouth. Chewing the MP-CarX resulted in lower levels of these processes, highlighting the importance of considering the oral phase of digestion when studying the hypoglycemic effects of polysaccharides. This is essential for developing new and effective approaches to improving glycemic control by incorporating fibers into commonly consumed starchy foods.

The eating rate of bread predicted from its sensory texture and physical properties

Eating rate (ER) can moderate energy intake and ER can be modified by the texture and physical properties of food. However, the magnitude of the effects is not well known. The aim of this study was to investigate how bread texture and physical properties determine ER. In a randomised crossover study, 36 healthy participants (age: 25 ± 6 years, BMI: 22 ± 2 kg m-2) consumed nine different bread types. Video coding was used to characterise oral processing behaviour. Sensory texture was evaluated on visual analogue scales. Physical properties were measured using texture profile analysis, puncture tests, geometrical and water-related measures. Two models were developed using response surface methodology (RSM) that predict the ER based on sensory and physical properties. The results showed from slow to fast ER: bread slices < hard buns < soft buns. The slowest bread type (wholemeal bread slice) was consumed 40% slower than the fastest bread type (soft white bun) (P < 0.001), explained by smaller bite sizes and more chews. For the sensory texture, ER was positively correlated with crumb adhesiveness and negatively correlated with crumb dryness. For the physical properties, ER was positively correlated with height and volume, and negatively with crumb cohesiveness and crust hardness. The models based on physical properties (R2 = 0.91) and sensory texture (R2 = 0.89) were both able to estimate ER, but the model based on physical properties performed slightly better. The insights from the relationships from the sensory and physical measures can both be used to modify the texture of breads, to effectively decrease ER and eventually help to prevent overconsumption.

Oral processing of bakery products: An overview of current status and future outlook

Food oral processing (FOP) is an emerging research topic that allows a better comprehension of the relation between intrinsic food factors (physicochemical and sensory properties), and human physiology and eating behaviours. FOP can then help in the design of novel and healthier food to meet both quality requirements and consumer needs. In this context, this review presents the current state of knowledge and new insights for future research concerning FOP of bakery products. The application of FOP in bakery science is new, with different protocols and related evaluation being applied, as detailed in this review. The current knowledge shows that bread structure and texture, influenced by formulation and process conditions, as well as the crust and shortenings present, impact bread breakdown and bolus formation, sensory perception, and food physiological effects such as glycaemic response, satiation, and satiety. For a better comprehension of oral processing, cross-modal perception between sensory attributes is used to understand consumer perception and this is carried out using both in vivo, and in vitro methods. This review highlighted the great potential of FOP to assist researchers and producers to face the current challenges relating to i - salt, fat and sugar reduction in bakery products to fulfil current food nutrition policies, ii - the design of healthier bakery products, and iii - the development of bakery products for consumers with special dietary requirements and ageing needs. In conclusion, FOP shows great potential to assist in the development of novel and healthier foods to meet actual food nutrition policies and consumer needs and should be more explored in bakery science and production.

Observation and Analysis of In Vitro Digestibility of Different Breads Using a Human Gastric Digestion Simulator

The digestion behavior of a food bolus comprising bread particles in the presence of gastric peristalsis remains poorly understood. This study systematically investigated the effect of bread type on in vitro gastric digestion behavior using a human gastric digestion simulator (GDS) that is capable of quantitatively simulating gastric peristalsis. A food bolus consisting of 60 g of bread (white bread, bagel, German bread, French bread, or croissant), 15 mL of a simulated salivary fluid, and 240 mL of a simulated gastric fluid was used for gastric digestion in vitro using the GDS for 3 h at 37 °C. Direct observation of the gastric digestion behavior in the GDS vessel demonstrated that the structure and composition of breads considerably influenced the physical digestion processes of bread particles. These processes include their fracture, rubbing, disintegration, swelling owing to the penetration of gastric fluid, and release of fat from their surface. Fluorescence microscopy enabled an improved understanding of the variations in the microstructure and major component distribution of the breads during the gastric digestion in vitro. The results showed how the different breads influenced gastric digestibility in vitro through quantitative gastric peristalsis. The GDS can also be applicable to studying gastric digestibility in vitro of other types of bread.

Effect of modifying pumpkin preparation on oral processing of breads

There is an increasing demand for texture sensations of bread during mastication, with reformulation being needed. This study investigated how bread structure influences oral processing behavior and texture perception. Variations in bread structure were created by manipulating ingredient additions, including pumpkin content and pumpkin processing methods. Results indicated that the physical, chemical, and structural properties drove the oral processing behaviors, and texture sensations were highly correlated with bolus properties. At the beginning and middle of the mastication, bolus from breads with low pumpkin-content required more saliva and exhibited greater hardness, lower adhesiveness, and a higher proportion of small-piece particles than the bolus from high pumpkin-content breads. Bolus from pumpkin pulp breads required more saliva, and was softer, stickier, and generated particles with a lower degree of degradation than the bolus from pumpkin puree breads. However, at the end period, the bolus properties tended to change to similar values. Low pumpkin content breads were initially perceived chewy, whereas high pumpkin content, soft. The dominance rate for soft sensation was higher and lasted longer in breads with pumpkin puree than in breads with pumpkin pulp. Finally, six bread samples were all perceived as hydrated, sticky, and crumbly. This study contributes to a better understanding of the impact of reformulation on oral behavior and sensory properties.

Effect of salivary fluid characteristics on the physical features of in vitro bread bolus: From the absence of saliva to artificially simulated hypersalivation

Saliva facilitates food oral processing, bolus formation, swallowing, and sensory perception, in addition to contributing to oral health and phonation. Ageing, health affections, and polymedication are among many causes altering salivary production, modifying the mastication process, the food impregnation ratio, and in turn altering the characteristics of the bolus, swallowing, and digestion. In this in vitro work, using the AM2 masticator apparatus, which replicates the mechanical actions taking place while chewing solid foods and produces realistic food bolus in various oral conditions, we investigated the effect of salivary fluid characteristics, i.e., composition, quantity (from absence to hypersalivation), temperature, and enzymatic action, on the physical characteristics (i.e., particle size distribution (PSD), bolus mass, salivary fluid content) of in vitro boluses of Traditional French baguette. A ready-to-swallow bolus of baguette displayed on average a d50 value (median particle size by mass) of 4.1 ± 0.4 mm, with saliva fluid constituting ∼ 35 % of the final bolus mass. The absence of saliva in mouth led to a deficient oral processing, forming bread boluses constituted by extremely big particles (ca. 80 % of particles had a size > 7.1 mm) that likely cannot be swallowed safely. On the contrary, an excess of saliva favoured an excessive breaking down of bread, leading to bread boluses constituted by smaller particles than those formed under healthy salivary conditions (d50 decreased from 4.1 mm to 3.1 mm), having a higher salivary fluid content (+10 %). On the other hand, the salivary fluid temperature did not affect PSD, d50, bolus mass, or salivary fluid content of in vitro bread boluses, however, the addition of human salivary α-amylase did, favouring particle size reduction (d50 decreased to 2.6 mm). Therefore, beyond the correlation between bolus hydration by saliva and food properties such as hardness and moisture content, our findings indicate that the quantity of salivary fluid present in the oral cavity and the enzymatic activity of salivary α-amylase during bread mastication significantly influence both the particle size distribution and the fluid content of bread boluses, ultimately determining the physical properties of the bolus and, therefore, potentially impacting the subsequent swallowing process.

The heat is on: Consumers modify their oral processing behavior when eating spicy foods

Food texture properties and consumer characteristics influence oral processing behaviors. Little is known about oral processing behavior of pungent spicy foods. In two experiments, we investigated how adding ground dried chilies to tomato soup or beef patties and curried rice altered oral processing behaviors. In Experiment One, tomato soups differing in concentration of added ground dried chilies (0.01, 0.03, 0.20 or 0.40% w/w) were consumed (n = 23). In Experiment Two, lunch meals that differed in added ground dried chilies consisting of beef patties (0.0, 0.6 or 1.2% w/w) and curried rice (0.0, 0.4 or 1.0% w/w) were consumed (n = 49). Sip/bite sizes were determined using hidden balances. Oral processing behavior was quantified using video recordings followed by post hoc annotations of specific behaviors. When eating tomato soup, increasing oral burn was associated with increasing number of water sips, water intake and total time between sips. For the solid meals (beef patties and curried rice), increasing oral burn was associated with increased time between bites and total sips of water; conversely, total oral exposure time, total number of chews and number of chews per bite all decreased with greater burn. Saliva content and rate of saliva incorporation into the solid food bolus increased with added ground dried chilies while oral exposure time decreased. We conclude consumers adapt their oral processing behaviors to oral burn of solid foods by reducing oro-sensory exposure time, chewing bites less, increasing time between bites, and consuming more water, potentially to mitigate the discomfort associated with the burn imparted by ground dried chilies.

Quantitative magnetic resonance imaging of in vitro gastrointestinal digestion of a bread and cheese meal

The monitoring of food degradation during gastrointestinal digestion is essential in understanding food structure impacts on the bioaccessibility and bioavailability of nutrients. Magnetic Resonance Imaging (MRI) has the unique ability to access information on changes in multi-scale structural features of foods in a spatially resolved and non-destructive way. Our objective was to exploit various opportunities offered by MRI for monitoring starch, lipid and protein hydrolysis, as well as food particle breakdown during the semi-dynamic in vitro gastrointestinal digestion of complex foods combined in a meal. The meal consisted of French bread, hard cheese and water (drink), with a realistic distribution of bolus particle sizes. The MRI approach was reinforced by parallel chemical analysis of all macronutrients in the supernatant. By combining different imaging protocols, quantitative MRI provided insights into a number of phenomena at the level of the cheese and bread particles and within the liquid phase that are hard to access through conventional approaches. MRI thus revealed the progressive ingress of fluids into the bread crust and the release of the gas trapped in the crumb, the erosion of cheese particles, the creaming of fat, the disappearance of small food particles and changes in liquid phase composition. Excellent agreement was obtained between the quantitative parameters extracted from the MRI images and the results of the chemical analysis, demonstrating the strong potential of MRI for the monitoring of in vitro gastrointestinal digestion. The present study proposes further improvements to fully exploit the capabilities of MRI and constitutes an important step towards the extension of quantitative MRI to in vivo studies.

What is the food like that people choke on? A study on food bolus physical properties under different in vitro oral capacities

People with oral impairments, such as poor denture status, poor muscle strength, and poor salivary secretion, have more difficulties performing oral processes, which results in the risk of choking. In this study, we aimed to understand, in vitro, how different oral impairments can affect the oral processing of food reported as a choking hazard. Six foods that frequently cause choking were selected and studied, varying three in vitro factors at two levels-saliva incorporation amount, cutting activity, and compression action. The median particle size (a50) and the particle size heterogeneity (a75/25) of the food fragmentation, the hardness, and adhesiveness of the bolus formation, and the final cohesiveness of the bolus were studied. The results showed that all the parameters studied varied depending on the food product. High compression reduced a50 (except in mochi that increased) and a75/25 (except in eggs and fish) but increased bolus adhesion and particle aggregation (except for mochi). Regarding cutting activity, when performing a greater number of strokes, the particle size for sausage and egg, and the hardness of the bolus for mochi and sausage were lower. In contrast, for some food products, the bolus adhesiveness (bread) and particle aggregation (pineapple) were higher at a high number of strokes. The amount of saliva also played an important role in the creation of the bolus. When high amounts of saliva were added, the a50 values (mochi) and hardness (mochi, egg, and fish) decreased; and increased the adhesiveness (mochi) and particle aggregation (bread, pineapple, and sausage). When all oral factors are compromised (lack of muscle strength, denture status, and saliva secretion), some food products create a choking hazard as individuals cannot achieve the right particle size, bolus cohesiveness, and mechanical properties of the bolus to be safe to swallow, there is still a need to elaborate a guide, considering all the safety parameters.

Bioaccessibility of Plant Sterols in Wholemeal Rye Bread Using the INFOGEST Protocol: Influence of Oral Phase and Enzymes of Lipid Metabolism

Bioaccessibility of plant sterols (PS) in an enriched wholemeal rye bread was evaluated, for the first time, using the INFOGEST protocol without gastric lipase (GL) and cholesterol esterase (CE), with GL or GL + CE. Moreover, human chewing and an in vitro oral phase (simulated salivary fluid and α-amylase) were evaluated for this purpose. The addition of GL decreased the bioaccessibility of total PS (from 23.8 to 18.5%), whereas the use of GL + CE does not significantly affect PS bioaccessibility. The in vitro oral phase resulted in an ineffective homogenization of the fresh vs partially dried and milled bread, reducing the bioaccessibility of total (from 20.2 to 12.8%) and individual PS. The INFOGEST digestion including the use of GL and CE, as well as an oral phase with human chewing, is proposed for the assessment of PS bioaccessibility in a solid matrix such as wholemeal rye bread since it more closely approximates the in vivo situation.

Guiding the formulation of soft cereal foods for the elderly population through food oral processing: Challenges and opportunities

As the elderly population is growing steadily, more age-friendly food products that allow them to cover their nutritional needs and are enjoyable need to be designed. Since their oral physiology is considerably altered, the study of Food Oral Processing has become an essential discipline in food development, as it takes into consideration the complex interactions between food structure, oral processing, physiology and perception. Cereals are staple foods in many countries, and their consumption as bakery products is popular among the elderly population. In addition, when fortified with pulse proteins, they can help meet the protein needs of seniors and help fight against sarcopenia. For these reasons, this chapter presents an overview of the various aspects involved in the oral processing and formulation of soft cereal foods, translating them into challenges and opportunities that are of relevance to the design of realistic soft cereal foods targeted for the elderly that are nutritious and sensory appealing. This review focuses on the healthy elderly population and does not intend to cover the needs of the dependent elderly suffering from chronical diseases.

Effect of Hemp Seed Oil Addition on the Rheological Properties of Dough and Bread

The aim of the study was to determine the influence of hemp seed oil on the rheological properties of the dough and the properties of white and black wheat flour bread. In this work, the dough was obtained from wheat flour types 550, 650, and 1350 to which hemp seed oil was added in percentages ranging from 0–15% (flour-based). The empirical and fundamental rheological properties of the dough were characterization using an alveograph test and a rotational rheometer. The rheological properties determined by the alveograph test indicated a correlation between the dough extensibility index and the bread volume. The obtained results led to the conclusion that the addition of oil in the dough, at a maximum percentage of 15%, modifies rheological properties by decreasing the modulus of viscosity and elasticity. Textural properties were used to determine hardness, springiness, cohesiveness, and adhesiveness. The hardness and softness of the bread decreased as the percentage of added oil increased and the elasticity of the bread samples increased with the addition of more oil. Supplementing bread with oil has led to improved textural features and sensory scores. Generally, the best quality was obtained at the optimum usage level of 5–10% hemp oil.

The contribution of gastric digestion of starch to the glycaemic index of breads with different composition or structure

Breads of higher density exhibit lower glycaemic index (GI) both in vivo and in vitro, a phenomenon generally attributed to a slower intestinal starch digestion. The aim of this work was to gain a better understanding of the relationship between bread density, oral and gastric digestion, and GI. Three breads were studied: industrial-style and traditional-style French baguettes (similar composition, different densities), and whole-wheat baguette. In vitro GI predictions confirmed that, for an identical composition, higher bread density was associated with a lower GI. Subsequent oro-gastric digestions, using the dynamic system DIDGI®, showed extensive starch digestion at the gastric stage by salivary α-amylase, in line with recently published data. They further showed that higher bread density led to a lower hydrolysis rate. The concurrence of these results with those of in vivo studies, suggests a mediating role for gastric digestion in the relationship between bread density and GI, possibly via the repercussions on the starch proportion that remains to be hydrolysed in the small intestine. This study therefore adds to the scientific knowledge of the importance of salivary α-amylase to starch digestion, and draws special attention to the possible role of the gastric phase in determining the GI.

A secret of salivary secretions: Multimodal effect of saliva in sensory perception of food

Saliva plays multifunctional roles in oral cavity. Even though its importance for the maintenance of oral health has long been established, the role of saliva in food perception has attracted increasing attention in recent years. We encourage researchers to discover the peculiarity of this biological fluid and aim to combine the data concerning all aspects of the saliva influence on the sensory perception of food. This review presents saliva as a unique material, which modulates food perception due to constant presence of saliva in the mouth and thanks to its composition. Therefore, we highlight the salivary components that contribute to these effects. Moreover, this review is an attempt to structure the effects of saliva on perception of different food categories, where the mechanisms of salivary impact in perception of liquid, semi-solid, and solid foods are revealed. Finally, we emphasize that the large inter-individual variability in salivary composition and secretion appear to contribute to the fact that everyone experiences food in their own way. Therefore, the design of the sensory studies should consider the properties of volunteers' saliva and also carefully monitor the experimental conditions that affect salivary composition and flow rate.

Understanding relations between rheology, tribology, and sensory perception of modified texture foods

The aim of this work was to examine relations between instrumental and sensory parameters in a texture modified food matrix, with and without saliva. Nine pureed carrot samples (eight thickened and a control) were developed with starch (0.4 and 0.8% wt/wt), xanthan (0.2 and 0.4% wt/wt) or starch-xanthan blends that met International Dysphagia Diet Standardisation Initiative (IDDSI) Level 4 guidelines using fork and spoon tests. Rheological and tribological tests were conducted on the food and simulated bolus prepared by adding fresh stimulated saliva to the food (1:5, saliva:food) to mimic oral processing. Perceived sensory properties were identified using a temporal dominance of sensations (TDS) test (n = 16) where panelists were given a list of nine attributes. The area under the curve was extracted from TDS curves for each attribute/sample and this was correlated with rheological (viscosity at 10 s^-1 , G', G″, and tan δ at 1 Hz) and tribological (friction coefficient in three regimes) data. The viscosity of the control sample decreased after adding hydrocolloids (except Starch_0.8%) and with saliva incorporation. G' and G″ either increased or were similar for xanthan and blends and decreased for starch-thickened samples. Hydrocolloid addition increased friction for all samples and was higher with saliva addition. Sensory results showed that samples with starch were perceived as thick and grainy while xanthan was perceived as smooth and slippery. A greater number of sensory attributes correlated with viscoelastic parameters compared to friction coefficients. Correlations were highest with the saliva added samples, further highlighting the importance of including saliva during instrumental testing.

Bread breakdown pathways during mastication: impact of wheat bran fortification

The aim of this study was to investigate the impact of wheat bran fortification on the mastication process of bread. White wheat bread (WB) and bran-fortified wheat bread (BB) were consumed by eighteen panellists. The bolus was collected at four different mastication stages and characterized by properties of hydration, particle size, and texture. The results showed that there was no difference between the two bread samples in terms of swallowable bolus moisture. BB with a harder and denser texture produced more small particles and had a slightly shorter chewing time than WB during mastication. Moreover, bolus heterogeneity (D₇₅/D₂₅) indicated a distinct difference among mastication stages and revealed different disintegration pathways between the two samples: BB bolus exhibited a monotonous particle size reduction during mastication with reducing D₅₀ and D₇₅/D₂₅; whereas, WB displayed a combination pattern of disintegration and agglomeration featuring relatively steady D₅₀ and fluctuating D₇₅/D₂₅. It was concluded that bran fortification changed the bread breakdown pathways in terms of bread disintegration and bolus formation during the mastication process. This information offers new guidelines for fortifying innovative materials to manufacture foods specifically targeted for health.

Size and Number of Food Boluses in the Stomach after Eating Different Meals: Magnetic Resonance Imaging Insights in Healthy Humans

Oral processing of food results in the formation of food boluses, which are then swallowed and reach the stomach for further digestion. The number, size and surface properties of the boluses will affect their processing and emptying from the stomach. Knowledge of these parameters, however, is incomplete due to limitations of the techniques used. In this work, non-invasive magnetic resonance imaging (MRI) was used for the first time to measure boluses in the stomach a few minutes after swallowing. Three groups of nine healthy participants were fed three different meals: chicken and roasted vegetables (Meal 1), bread and jam (Meal 2) and cheese and yogurt (Meal 3), and then, their stomach content was imaged. The median number of boluses within the stomach was 282, 106 and 9 for Meal 1, Meal 2 and Meal 3 (p < 0.0001) with an average volume of 0.47 mL, 2.4 mL and 13.6 mL, respectively (p < 0.0001). The cohesiveness as well as the meal composition seem to play a key role in the resulting boluses. These new in vivo data from undisturbed organ imaging can improve knowledge of the digestion process, which will, in turn, inform in vitro and in silico modelling of digestion, thus improving their in vitro/in vivo relevance.

Mastication of crisp bread: Role of bread texture and structure on texture perception

Texture and structure of breads have been related to oral processing (FOP) performance and sensory perceptions, but moisture content might play a significant role. To evaluate the real impact of breads texture and structure, eliminating the possible role of moisture content, different toasted breads were investigated. Four commercial toasted sliced breads (white bread -WHB-, whole wheat bread -WWB-, non-added sugar bread -NSU-, non-added salt bread -NSA-) with similar ingredients but different texture and structure were selected. Texture and structure were instrumentally and sensory evaluated, besides FOP (total chewing time, number of chews until swallowing, chewing frequency, and mouthful) and bolus properties (moisture, saliva to bread ratio, hardness, adhesiveness, and cohesiveness). Toasted breads showed significant differences in hardness, cutting strength, and porosity, but panelists did not discriminate among them. FOP results indicated that harder samples (NSU) required longer mastication and a number of chews, and open crumb structures (WWB, WHB) with higher cell areas required less mastication. Also, bolus characteristics were affected by bread types, and bread with lower crumb hardness (WHB) produced more cohesive bolus. Having toasted breads allowed to eliminate possible influence of moisture content differences on sensory perception, mouthful and bolus water incorporation during mastication.

Understanding the oral processing of solid foods: Insights from food structure

Understanding the relationship between the structure of solid foods and their oral processing is paramount for enhancing features such as texture and taste and for improving health-related factors such as management of body weight or dysphagia. This paper discusses the main aspects of the oral processing of solid foods across different categories: (1) oral physiology related to chewing, (2) in-mouth food transformation, (3) texture perception, and (4) taste perception, and emphasis is placed on unveiling the underlying mechanisms of how food structure influences the oral processing of solid foods; this is exemplified by comparing the chewing behaviors for a number of representative solid foods. It highlights that modification of the texture/taste of food based on food structure design opens up the possibility for the development of food products that can be applied in the management of health.

Bolus rheology of texture-modified food: Effect of degree of modification

Swallowing disorders, or dysphagia, require an intake of texture-modified foods progressively softer, smoother, and moister depending on the severity of the disorder. Bolus rheology was determined for five healthy subjects for a set of such solid foods regularly given to dysphagia patients. The softest class was gel food, then a smooth timbale which both were compared to the corresponding regular, un-modified food. The foods investigated were bread, cheese, tomato, and the combination as a sandwich, all for the respective texture class: gel, timbale, and regular food. The subjects chewed until ready to swallow and the expectorated bolus was immediately measured for complex shear modulus and viscosity, and moisture and saliva content were determined. Rheology show that texture-modification influenced bolus rheology with decreased viscosity and modulus for increased degree of modification. Also saliva content as well as chews-to-swallow decreased with degree of modification. Overall, the bolus saliva content was lower for the combination (sandwich) than for the individual components. Saliva content was fairly constant irrespective of food moisture content. The phase angle for all boluses was also relatively constant, indicating a similar bolus structure. All boluses of the texture-modified foods showed high extensional viscosity, which is important for bolus cohesiveness. Bolus rheology rather than food texture determines if a food is safe to swallow and the results show that the intended texture-modification is reflected in the flow properties of the respective boluses.

The effect of a bread matrix on mastication of hazelnuts

The effect of the degree of nut mastication on bioavailability of their nutrients has been established previously. In contrast, the effect of incorporation of nuts into composite food matrixes on oral processing behaviour and structural breakdown has been studied scarcely. This study aimed to investigate the effect of incorporation of hazelnuts into bread matrixes in comparison with plain hazelnuts on bolus properties and chewing behaviour. Amount of plain hazelnuts was varied to investigate the effect of portion size on bolus properties and chewing behaviour. Bolus particle size distribution was obtained by image analysis of expectorated boli by n = 20 participants. Median bolus particle diameter (d₅₀) and broadness of particle size distribution (b) were quantified by fitting the cumulative area distribution curve with a modified Rosin-Rammler function. Oral processing behaviour (number of chews, chewing time, chewing frequency) was quantified by means of a stopwatch. Mastication of two hazelnuts resulted in smaller d₅₀ than mastication of six hazelnuts or mastication of two hazelnuts in white bread or baguette. Chewing time of two hazelnuts was significantly shorter than chewing time of six hazelnuts or chewing time of two hazelnuts in white bread or baguette, while chewing frequency did not differ between foods. d₅₀ of six hazelnuts did not significantly differ from d₅₀ of two hazelnuts in either bread matrix. Broadness b of the particle size distribution was significantly smaller for six hazelnuts compared to the other foods. We conclude that d₅₀ was affected by bite size or bite volume rather than by incorporation of hazelnuts into bread. We suggest that incorporation of hazelnuts into bread matrixes has a relatively small impact on size of hazelnut bolus particles produced upon mastication.

Evaluation of texture of cheese by-products incorporated bread

Abstract This work aimed to develop new breads incorporating whey residue, “sorelho”, obtained from ewe’s milk after the production of Serra da Estrela Cheese. For this, we baked three types of bread: wheat bread (control sample), bread incorporating sorelho, and another version containing additional nutritional elements. The texture was evaluated with a texturometer, using compression and perforation tests. Results showed that sorelho can be successfully incorporated in bread. The best product was the bread with sorelho plus improved nutrition, which presented good textural characteristics during a period of 24 hours. This trend was observed for all properties evaluated: hardness, chewiness, resilience, cohesiveness, springiness (compression test) and external firmness, inner firmness, stickiness, adhesiveness (perforation test). Finally, factor analysis showed: FACTOR 1 – compression textural properties; FACTOR 2 – perforation firmness properties and FACTOR 3 – perforation adhering properties, which in total explained approximately 81% of total variance.

Characterization of the aroma release and perception of white bread during oral processing by gas chromatography-ion mobility spectrometry and temporal dominance of sensations analysis

The purpose of this study was to investigate the aroma release and perception from white bread during oral processing by gas chromatography-ion mobility spectrometry (GC-IMS) and dynamic sensory evaluation of temporal dominance of sensations (TDS). TDS curves indicated that two maximum aroma perception signals, fermentation-like and flour-like attributes, were perceived at the beginning and swallowing, respectively. The fermentation-like, flour-like, and sour attributes were the 3 dominant aromas during oral processing. A total of 35 volatile compounds were detected in the mouth cavity during chewing white bread, 19 of them were confirmed and quantified by using the respective external standard. Based on PLSR analysis, 8 aroma compounds were predicted as potent odorants contributing to the aroma perception from chewing white bread. By application of odor activity values analysis and addition experiments, ethyl butanoate, butyl acetate, hexanal, 3-(methylthio)-propanal, 3-methylbutanal, and 2,3-butanedione were confirmed as the key odorants contributing to the aroma perception during chewing of white bread.

Potential Impact of Oat Ingredient Type on Oral Fragmentation of Biscuits and Oro-Digestibility of Starch-An In Vitro Approach

The aim of the present study was to determine how variation in the biscuit matrix affects both the degree of in vitro fragmentation and the starch hydrolysis that occurs during the oral phase of digestion. Using three different oat ingredient types (oat flour, small flakes, and big flakes) and baking powder (or none), six biscuits with different matrices were obtained. The instrumental texture (force and sound measurements) of the biscuits was analyzed. The samples were then subjected to in vitro fragmentation. The particle size distribution and in vitro oral starch hydrolysis over time of the fragmented samples were evaluated. The results showed that the samples presented different fragmentation patterns, mainly depending on the oat ingredient type, which could be related to their differences in texture. The biscuits made with oat flour were harder, had a more compact matrix and showed more irregular fragmentation and a higher percentage area of small particles than those made with big oat flakes, which were more fragile and crumbly. The highest degree of starch hydrolysis corresponded to the biscuits made with flour. Conclusions: Differences in the mechanical properties of the biscuit matrix, in this case due to differences in the oat ingredient, play a role in the in vitro fragmentation pattern of biscuits and in the oral phase of starch hydrolysis.

In vitro digestion of bread: How is it influenced by the bolus characteristics?

This study aimed to understand the impact of in vitro oral processing methods on bolus formation and the kinetics of starch hydrolysis of refined white bread during in vitro gastrointestinal digestion. Four in vitro oral processing methods (i.e., cut, cut-and-pestle, blend, and grind) were performed at two levels of disintegration (less and more intensive) and compared with human mastication. Boluses prepared using the in vitro methods had a larger particle size (20-69 mm² vs. 14 mm² ), a higher moisture content (64-68% vs. 47%), a softer texture (1.3-2.3 N vs. 6.3 N) and a less adhesive surface (0.3-1.0 vs. 1.6 N•s) as compared to the in vivo masticated ones. Moreover, in vitro prepared blouses were digested more rapidly than in vivo masticated ones during the stimulated intestinal digestion from 150 min onward, with a higher hydrolysis rate (0.011-0.012 mg/mL • min vs. 0.010 mg/mL • min) and a higher equilibrium concentration of reducing sugar (5.5-6.3 mg/mL vs. 4.9 mg/mL). Among all the in vitro methods, the blending and grinding methods produced boluses that most closely resemble the in vivo masticated ones in terms of their physical characteristics. The blending method also produced boluses having the highest amount of reducing sugar released (6.32 mg/mL). The amount of reducing sugar present in the PBS buffer outside the dialysis tube might be controlled by the diffusion efficiency at the beginning of the digestion (≤120 min) and then be largely influenced by the particle size of the bolus in the latter stage of the digestion. PRACTICAL APPLICATION: Studying the in vitro starch amyloysis is valuable for predicting the postprandial glycemic potential of starchy food. This work provides novel insights on the role of in vitro oral processing in the prediction of the glycemic potential of carbohydrate-rich staple food. Blending method is recommended because of its ability to produce boluses with similar physical characteristics as the in vivo masticated boluses. But the excessive structural breakdown occurred during blending also resulted in a higher enzymatic accessibility and a higher rate of starch digestion. Further study is needed to propose a new in vitro method that stimulates multiple actions occurred during mastication (cutting, grinding, and shearing), in order to match both physical properties and digestion profiles. Moreover, the amount of artificial saliva added should be adjusted according to the specific type of food.

The important role of salivary α-amylase in the gastric digestion of wheat bread starch

The role of salivary α-amylase (HSA) in starch digestion is often overlooked in favour of that of pancreatic α-amylase due to the short duration of the oral phase. Although it is generally accepted that the amylase of salivary origin can continue to be active in the stomach, studies ascertaining its contribution are lacking. This study aimed to address this issue by coupling in vitro oral processing with an in vitro dynamic system that mimicked different postprandial gastric pH reduction kinetics observed in vivo following a snack- or lunch-type meal. The digestion of both starch and protein from wheat bread as well as the interplay between the two processes were studied. We have observed that the amylolytic activity of saliva plays a preponderant role hydrolysing up to 80% of bread starch in the first 30 min of gastric digestion. Amylolysis evolved exponentially and nearly superimposing curves were obtained regardless of the acidification profiles, revealing its high efficiency.

Relationships of oral comfort perception and bolus properties in the elderly with salivary flow rate and oral health status for two soft cereal foods

The aim of this study was to investigate food oral processing and bolus formation in the elderly population, and their relationship with the perception of oral comfort, for two soft cereal products of different composition: sponge-cake and brioche. Twenty subjects aged 65 and over participated in the study. They were classified in two groups according to dental status (poor vs. satisfactory) and presented various stimulated salivary flow rate (SSF) in each group. Food bolus properties (hydration ratio and apparent viscosity) were characterized after three chewing stages for both groups. Results showed that chewing duration did not depend on food product but rather on physiology: subjects with a poor dental status had a shorter chewing duration. For each chewing stage, sponge-cake boli showed a higher hydration ratio than brioche boli, which showed higher apparent viscosity. For sponge-cake, perception of oral comfort was primarily driven by SSF rate, irrespective of the dental status. In the case of brioche, oral comfort was also partially explained by SSF in the case of subjects with poor dental status. This result suggests that perception of oral comfort in brioche could be driven by product related attributes rather than oral health. For both foods, a phenomenological model of bolus viscosity as a function of stimulated salivary flow and chewing duration was proposed.

Chewing bread: impact on alpha-amylase secretion and oral digestion

During chewing, saliva helps in preparing the food bolus by agglomerating the formed particles, and it initiates enzymatic food breakdown. However, limited information is actually available on the adaptation of saliva composition during the oral processing of complex foods, especially for foods that are sensitive to salivary enzymes. We addressed this question in the context of starch-based products and salivary alpha-amylase. The objectives were two-fold: (1) to determine if salivary alpha-amylase secretion can be modulated by the bread type and (2) to evaluate the contribution of the oral phase in bread enzymatic breakdown. Mouthfuls of three different wheat breads (industrial, artisan and whole-meal breads) were chewed by twelve subjects. Saliva samples were collected at rest and at different times corresponding to 33, 66 and 100% of the individual's chewing sequence. Alpha-amylase activity and total protein content were determined for all saliva samples that were collected. Additionally, the salivary maltose concentration was measured as a marker of bread enzymatic digestion. Boluses were collected at the swallowing time to evaluate the saliva uptake. Chewing industrial bread induced higher saliva uptake than the other breads despite a similar chewing duration. The evolution of salivary amylase activity tended to depend on the type of bread and was highly influenced by a large degree of inter- and intra-subject variability. The protein and maltose concentration steadily increased during chewing as a result of bread breakdown. The salivary protein concentration was mainly affected by the release of the water-soluble proteins of the bread. The salivary maltose concentration was found to be significantly lower for the whole-meal bread. When considering the weight of the mouthful, enzymatic breakdown was found to be most efficient for the breads ranking from industrial > artisan > whole-meal.

Effect of Bread Crumb and Crust Structure on the in Vivo Release of Volatiles and the Dynamics of Aroma Perception

This study examined the effects of bread crumb and crust structure on volatile release and aroma perception during oral processing. French baguettes with different crumb structures were procured from a supermarket or local bakeries (n = 6) or produced in the laboratory via par baking (n = 3). Eight study participants consumed crumb-only and crumb-and-crust samples, and the resulting volatile release was measured in vivo using proton transfer reaction-mass spectrometry. A statistical model was then used to examine the contributions of volatile compounds to target ion production (i.e., crumb or crust markers). Utilizing the three laboratory-produced breads, chewing behavior and aroma perception were measured via electromyography and the temporal dominance of sensations method, respectively. The results revealed that the initial levels of crumb markers as well as crumb firmness affected the crumb markers release. Crust markers were released more quickly than crumb markers, leading to different perception dynamics.