Impact of food texture modifications on oral processing behaviour, bolus properties and postprandial glucose responses.

Several studies have demonstrated food texture manipulation on oral processing behaviour (OPB). We explored the effect of texture-differences of equivalent carbohydrate load on OPB, bolus properties and postprandial glycaemic responses (PPG). In a randomised cross-over, within-subjects, non-blinded design, healthy male participants (N = 39) consumed fixed portions of white rice (WR) and rice cake (RC) while being video recorded to measure microstructural eating behaviours. PPG was compared between test foods over a period of 120-min, and the bolus properties and saliva uptake at swallow were measured for both test foods. RC displayed higher instrumental hardness, chewiness and Young's modulus than WR (p = 0.01), and participants perceived RC as more springy and sticky than WR (p < 0.001). The RC meal was chewed more per bite (p < 0.001) and consumed at a faster eating rate (p = 0.033) than WR. WR bolus particles were smaller at swallow (p < 0.001) with a larger total surface area (p < 0.001), compared to RC. The glucose response for RC was significantly higher during the first 30-min postprandial period (p = 0.010), and lower in the later (30-120 min) postprandial period (p = 0.031) compared to WR. Total blood glucose iAUC did not differ significantly between WR and RC meals despite their large differences in texture, OPB and bolus properties. Oro-sensory exposure time was a significant predictor of glucose iAUC30min for both test meals (RC, p = 0.003; WR, p = 0.029). Saliva uptake in the bolus was significantly positively associated with blood glucose during the first 30-min postprandial period for the RC meal (p = 0.008), but not for WR. We conclude that food texture modifications can influence OPB and bolus properties which are key contributors to the dynamic evolution of the glycaemic response. Total blood glucose responses were the same for both test foods, though differences in oral processing and bolus properties influenced temporal changes in PPG.

Physical and sensory characterisation of noodles with added native and denatured pea protein isolate.

Wheat noodles with added native or denatured pea-protein isolate were characterised for their starch-protein interaction, degree of starch gelatinisation, starch digestibility, textural and sensory properties using light microscopy, differential scanning calorimetry (DSC), in vitro digestion, textural profile analysis (TPA) and descriptive analysis respectively. It was hypothesised that denatured proteins with an unfolded structure, would have greater interaction with starch, thereby reducing the extent of gelatinisation and subsequent glucose release compared to native proteins. Results showed that the addition of denatured pea protein to a wheat noodle matrix produced a reduction in in vitro glucose release, which was supported by a lower degree of gelatinisation and greater binding of protein to the starch matrix visually. Addition of native protein to the noodles had less impact on degree of gelatinisation and glucose release. Addition of both proteins had a negligible effect on product texture and sensory perceptual properties.

Avoiding hunger or attaining fullness? Implicit goals of satiety guide portion selection and food intake patterns.

Although implicit theories have been studied in the context of personal traits, there has been limited investigation of their role in physiological domains such as appetite. Subjective feelings and affective states can function as goals and desired end states that individuals regulate their behaviors to attain. Likewise, different conceptualizations people maintain for the subjective experience of satiety (i.e., terminating hunger or attaining fullness) may also predict individual variations in eating behavior. We examined whether portion selection and food intake were guided by such implicit goals pertaining to the nature of satiety. Across 3 studies, we observed that individuals report distinct subjective requirements (degrees of fullness) to attain different states of satiety (stop hunger, feel comfortably full, feel completely full), suggesting that these states reflect independent goals or outcomes. Importantly, personal requirements to feel completely full (compared to stop hunger or feel comfortably full) were observed to be the strongest predictor of portion sizes selected in Study 1 (B = 1.17, p < .001) and Study 2 (B = 4.26, p = .004), and the quantity of energy consumed from a meal in Study 2 (B = 3.07, p = .01). Yet, experimentally activating a situational goal to stop hunger (vs. feel full) produced the selection of smaller portion sizes, F(1, 41) = 5.64, p = .02, and personal requirements to stop hunger to become the dominant predictor of portion selection patterns in Study 3 (B = 0.43, p = .005). These findings reveal that eating behaviors of modern consumers may be guided by a predominant goal to attain the subjective experience of complete fullness, although this implicit goal may be malleable to situational demands.

The role of perceived stress and gender on portion selection patterns.

Stress is linked to increased preferences and consumption of palatable energy dense foods, particularly among females. Despite the role of stress on potentially obesogenic eating habits, its effect on pre-meal planning, such as the selection of portion sizes, remain unknown. Here, we investigated the relationship between perceived stress, gender, and intended portion sizes for diverse foods. Across two studies, increased perceived stress predicted larger (higher energy) intended portion sizes across a variety of food items among females, but not males. Additionally, for females, increased perceived stress was associated with lowered expectations of the satiety of foods presented, suggesting a potential mechanism by which stress may influence decisions about portion size. These findings reveal that the potentially obesogenic effects of stress on food judgments and behaviours (particularly among females) are not only expressed within meals, but also during more deliberate stages of planning that precedes meals.

Personal relative deprivation increases self-selected portion sizes and food intake.

Cues and experiences of the deprivation of financial/material resources have been associated with increased caloric intake and risk for overweight/obesity. Given that social comparisons may serve as a powerful reference for the adequacy of one's standing and resources, the present research tested whether subjective feelings of personal relative deprivation (PRD) or "losing out" to others stimulates calorie selection and intake. Study 1 demonstrated that self-reported chronic experiences of PRD positively predicted calories selected for a portion and consumed during an ad-libitum meal. Study 2 revealed that experimentally-induced PRD resulted in an increase in the amount of calories selected on a portion selection task and a stronger desire to consume the foods. Consequently, these findings demonstrate that chronic and acute subjective deprivation of non-food resources may contribute to socioeconomic gradients in obesity, and that perceived social inequality may have inherently obesogenic properties that promote excess calorie intake.

Effects of non-nutritive (artificial vs natural) sweeteners on 24-h glucose profiles.

Replacing nutritive sweetener with non-nutritive sweeteners (NNS) has the potential to improve glycaemic control. The objective of this study was to investigate the effects of consuming artificial NNS (that is, aspartame), natural NNS (that is, monk fruit and stevia), and sucrose-sweetened beverages on 24-h glucose profiles. Ten healthy males took part in this randomised, crossover study with the following four treatments: aspartame-, monk fruit-, stevia-, and sucrose- (65 g) sweetened beverages. Participants were asked to consume the test beverage as a preload mid-morning. Medtronic iPro2 continuous glucose monitoring system was used to measure mean 24-h glucose, incremental area under the curve (iAUC) and total area under the curve (AUC) for glucose, and 24-h glycaemic variability. Overall no significant differences were found in mean 24-h glucose, iAUC and total AUC for glucose, and 24-h glycaemic variability between the four test beverages. Twenty-four-hour glucose profiles did not differ between beverages sweetened with non-nutritive (artificial vs natural) and nutritive sweeteners. The simple exchange of a single serving of sucrose-sweetened beverage with NNS over a day appears to have minimal effect on 24-h glucose profiles in healthy males.

Fast or slow-foods? Describing natural variations in oral processing characteristics across a wide range of Asian foods.

The structural properties of foods have a functional role to play in oral processing behaviours and sensory perception, and also impact on meal size and the experience of fullness. This study adopted a new approach by using behavioural coding analysis of eating behaviours to explore how a range of food textures manifest as the microstructural properties of eating and expectations of fullness. A selection of 47 Asian foods were served in fixed quantities to a panel of participants (N = 12) and their eating behaviours were captured via web-camera recordings. Behavioural coding analysis was completed on the recordings to extract total bites, chews and swallows and cumulative time of the food spent in the mouth. From these measurements a series of microstructural properties including average bite size (g), chews per bite, oro-sensory exposure time (seconds) and average eating rate (g min-1) were derived per food. The sensory and macronutrient properties of each food were correlated with the microstructure of eating to compare the differences in eating behaviour on a gram for gram basis. There were strong relationships between the perceived food textural properties and its eating behaviours and a food's total water content was the best predictor of its eating rate. Foods that were eaten at a slower eating rate, with smaller bites and more chews per bite were rated as higher in the expected fullness. These relationships are important as oral processing behaviours and beliefs about the potential satiating value of food influence portion decisions and moderate meal size. These data support the idea that naturally occurring differences in the food structure and texture could be used to design meals that slow the rate of eating and maximise fullness.

Effects of aspartame-, monk fruit-, stevia- and sucrose-sweetened beverages on postprandial glucose, insulin and energy intake.

BACKGROUND: Substituting sweeteners with non-nutritive sweeteners (NNS) may aid in glycaemic control and body weight management. Limited studies have investigated energy compensation, glycaemic and insulinaemic responses to artificial and natural NNS. OBJECTIVES: This study compared the effects of consuming NNS (artificial versus natural) and sucrose (65 g) on energy intake, blood glucose and insulin responses. METHODS: Thirty healthy male subjects took part in this randomised, crossover study with four treatments: aspartame-, monk fruit-, stevia- and sucrose-sweetened beverages. On each test day, participants were asked to consume a standardised breakfast in the morning, and they were provided with test beverage as a preload in mid-morning and ad libitum lunch was provided an hour after test beverage consumption. Blood glucose and insulin concentrations were measured every 15 min within the first hour of preload consumption and every 30 min for the subsequent 2 h. Participants left the study site 3 h after preload consumption and completed a food diary for the rest of the day. RESULTS: Ad libitum lunch intake was significantly higher for the NNS treatments compared with sucrose (P=0.010). The energy 'saved' from replacing sucrose with NNS was fully compensated for at subsequent meals; hence, no difference in total daily energy intake was found between the treatments (P=0.831). The sucrose-sweetened beverage led to large spikes in blood glucose and insulin responses within the first hour, whereas these responses were higher for all three NNS beverages following the test lunch. Thus, there were no differences in total area under the curve (AUC) for glucose (P=0.960) and insulin (P=0.216) over 3 h between the four test beverages. CONCLUSIONS: The consumption of calorie-free beverages sweetened with artificial and natural NNS have minimal influences on total daily energy intake, postprandial glucose and insulin compared with a sucrose-sweetened beverage.

Removing energy from a beverage influences later food intake more than the same energy addition.

Designing reduced-calorie foods and beverages without compromising their satiating effect could benefit weight management, assuming that consumers do not compensate for the missing calories at other meals. Though research has demonstrated that compensation for overfeeding is relatively limited, the extent to which energy reductions trigger adjustments in later food intake is less clear. The current study tested satiety responses (characterised by changes in appetite and later food intake) to both a covert 200 kcal reduction and an addition of maltodextrin to a soymilk test beverage. Twenty-nine healthy male participants were recruited to consume three sensory-matched soymilk beverages across four non-consecutive study days: a medium energy control (ME: 300 kcal) and a lower energy (LE: 100 kcal) and higher energy (HE: 500 kcal) version. The ME control was consumed twice to assess individual consistency in responses to this beverage. Participants were unaware of the energy differences across the soymilks. Lunch intake 60 min later increased in response to the LE soymilk, but was unchanged after consuming the HE version. These adjustments accounted for 40% of the energy removed from the soymilk and 13% of the energy added in. Rated appetite was relatively unaffected by the soymilk energy content. No further adjustments were noted for the rest of the day. These data suggest that adult men tested were more sensitive to calorie dilution than calorie addition to a familiar beverage.

Sensory influences on food intake control: moving beyond palatability.

The sensory experience of eating is an important determinant of food intake control, often attributed to the positive hedonic response associated with certain sensory cues. However, palatability is just one aspect of the sensory experience. Sensory cues based on a food's sight, smell, taste and texture are operational before, during and after an eating event. The focus of this review is to look beyond palatability and highlight recent advances in our understanding of how certain sensory characteristics can be used to promote better energy intake control. We consider the role of visual and odour cues in identifying food in the near environment, guiding food choice and memory for eating, and highlight the ways in which tastes and textures influence meal size and the development of satiety after consumption. Considering sensory characteristics as a functional feature of the foods and beverages we consume provides the opportunity for research to identify how sensory enhancements might be combined with energy reduction in otherwise palatable foods to optimize short-term energy intake regulation in the current food environment. Moving forward, the challenge for sensory nutritional science will be to assess the longer-term impact of these principles on weight management.

Oral processing characteristics of solid savoury meal components, and relationship with food composition, sensory attributes and expected satiation.

BACKGROUND: The modern food supply is often dominated by a large variety of energy dense, softly textured foods that can be eaten quickly. Previous studies suggest that particular oral processing characteristics such as large bite size and lack of chewing activity contribute to the low satiating efficiency of these foods. To better design meals that promote greater feelings of satiation, we need an accurate picture of the oral processing characteristics of a range of solid food items that could be used to replace softer textures during a normal hot meal. AIM: The primary aim of this study was to establish an accurate picture of the oral processing characteristics of a set of solid savoury meal components. The secondary aim was to determine the associations between oral processing characteristics, food composition, sensory properties, and expected satiation. METHODS: In a within subjects design, 15 subjects consumed 50 g of 35 different savoury food items over 5 sessions. The 35 foods represented various staples, vegetables and protein rich foods such a meat and fish. Subjects were video-recorded during consumption and measures included observed number of bites, number of chews, number of swallows and derived measures such as chewing rate, eating rate, bite size, and oral exposure time. Subjects rated expected satiation for a standard 200 g portion of each food using a 100mm and the sensory differences between foods were quantified using descriptive analysis with a trained sensory panel. Statistical analysis focussed on the oral processing characteristics and associations between nutritional, sensory and expected satiation parameters of each food. RESULTS: Average number of chews for 50 g of food varied from 27 for mashed potatoes to 488 for tortilla chips. Oral exposure time was highly correlated with the total number of chews, and varied from 27 s for canned tomatoes to 350 s for tortilla chips. Chewing rate was relatively constant with an overall average chewing rate of approximately 1 chew/s. Differences in oral processing were not correlated with any macronutrients specifically. Expected satiation was positively related to protein and the sensory attributes chewiness and saltiness. Foods that consumed in smaller bites, were chewed more and for longer and expected to impart a higher satiation. DISCUSSION: This study shows a large and reliable variation in oral exposure time, number of required chews before swallowing and expected satiation across a wide variety of foods. We conclude that bite size and oral-sensory exposure time could contribute to higher satiation within a meal for equal calories.

Texture and savoury taste influences on food intake in a realistic hot lunch time meal.

BACKGROUND: Previous studies with model foods have shown that softer textures lead to higher eating rates and higher ad libitum food intake and higher intensity of salt taste has been shown to result in a lower ad libitum food intake. These observations have yet to be replicated in the context of realistic solid hot meal components. AIM: The objective of the present study was to assess the effect of texture and taste on the ad libitum intake of a realistic hot lunchtime meal. METHODS: The meals consisted of potatoes, carrots, steak and gravy varied according to a 2 (texture: mashed vs. whole) × 2 (taste: standard taste vs. strong taste) design. The texture dimension referred to mashed potatoes, mashed carrots and pieces of steak vs. whole boiled potatoes, whole boiled carrots and whole steak. The taste was varied by manipulating the taste intensity of the gravy to be either standard or high intensity savoury taste. The current study used a between groups, single course ad libitum design whereby subjects were recruited for a one off meal study, during which their food intake was measured. The four groups consisted of about 40 subjects (mashed, standard, n=37; mashed, savoury n=39; whole, standard n=40; and whole, savoury n=41) matched for age (average age=44.8 ± 5.3), gender (on average 19 males and 20 females), normal BMI (average 22.6 ± 1.7) and dietary restraint score (DEBQ score=1.74 ± 0.6). RESULTS: The results showed that the estimated means of the intake of the two mashed conditions was 563.2 ± 20.3g and intake of whole meal was 527.5 ± 20.0 g (p=0.23). The texture effect was significant in the higher savoury condition with an average of 91 g less food consumed in the solid-savoury meal than in the mashed-savoury meal. This effect was not replicated in the standard gravy condition, with no significant difference between solid and mashed textures. This was reflected in an interaction effect that was approaching significance (p=0.051). The estimated mean eating rate in the two mashed conditions was 57.0 ± 2.5 g and was significantly higher than the whole meal condition (47.2 ± 2.5g (p<0.05), with no difference in eating rate between the standard and savoury gravy conditions. DISCUSSION: Although interpretation was made difficult by the between groups design and the interaction between taste*texture, the results nonetheless confirm the effect of texture on eating rate and ad libitum intake for solid savoury meal components. The impact of taste on ad libitum intake of a solid meal remains unclear. We conclude that people consumed more of the meal when the food was simultaneously mashed and savoury. Food texture may be used to produce slower eating rates that result in a reduced overall energy intake within a realistic hot lunchtime meal.

Interactions between texture and trigeminal stimulus in a liquid food system: effects on elderly consumers preferences.

Changes to the chemical senses of taste and smell that accompany ageing are widely believed to influence food preferences and consumption in the elderly. The possibility that interactions between the residual senses of texture and trigeminal perception can compensate for specific losses was explored using a complex liquid food system, soup. A consumer panel of twenty-four young people (20-35, mean age 27.7 +/- 3.95 years) and twenty-four elderly people (>65 years, mean age 73.6 +/- 5.78 years) were used for preference tests. Eight soups were prepared using a standardised recipe, with four variations in texture and two levels of trigeminal stimulus. The consumer panel preferences were measured using a nine point hedonic scale. The hedonic data was corrected for a scaling effect, and principle components analysis was completed on the normalised data of the two age cohorts. The preference decision of both age groups was in the direction of the lower level of trigeminal stimulation. Overall the older panel was less discriminating than the younger panel. However the older panel made an attempt to grade the different textures while the younger panel seemed to ignore the textural attribute in their preference decision. The older panel's preference decreased as the thickness of the soups increased across trigeminal levels. These results suggest that perhaps a judicious selection of a certain texture or mouthfeel combined with a preferred level of trigeminal irritation could boost elderly food enjoyment. Finally, a postal questionnaire was circulated to gain an insight in to the consumer's background and thus partially explain the motivation for their preferences.