Consumer acceptance and sensory drivers of liking for high plant protein snacks.

BACKGROUND: Consumers are being encouraged to increase the proportion of plant protein in their diet to tend to a sustainable food system. Solutions could include developing a food rich in plant protein. However, these new products have an interest only if they are in accordance with expectation and the liking of consumers. In this context, extruded snack balls were developed to explore the sensory drivers of liking and barriers to consumption of formulated products with a high level of plant proteins. Eight different products varying in the type of cereal flour (rice or wheat) and pea flour content (from 60% to 90%) were developed following a factorial design. Eighty omnivore and 72 flexitarian consumers were recruited to evaluate the liking of these products. In addition, their sensory properties were described by a trained panel according to a profile method. RESULTS: The cereal type had globally more influence on liking than the percentage of pea. However, liking was inversely correlated with pea flour content, regardless of the cereal type. The main drivers of liking are texture criteria (in particular crispy and puffy), whereas flavor perception (pea, green) constitutes a barrier to acceptance. Interestingly, very few differences of liking were observed depending on the diet of consumers even though the attitudes of flexitarian'towards such type of products differed from those of omnivores. We identified three clusters of consumers based on their preferences. Pea flavor acceptance or rejection could explain these clusters. Although most consumers rejected pea flavor, approximately 40% of the participants preferred the products with highest pea content. CONCLUSION: The results of the present study will help provide guidance for innovative plant food design and formulation. © 2019 Society of Chemical Industry.

Acceptance of added fat to first complementary feeding purees: An exploration of fat type, feeding history and saliva composition.

In adults, fat is a major determinant of food palatability. From the onset of complementary feeding (CF) adding fat to complementary foods is recommended to ensure an optimal growth and cognitive development. However, whether adding fat to complementary foods would impact acceptance (in terms of intake and liking) has been little investigated. This study sought 1) to evaluate acceptance of added fat (either vegetable oils or dairy fat) in a vegetable puree in weaning-age infants; 2) to determine whether early differential fat exposure through milk (breast milk and formula have different fat composition) and fat addition in complementary foods can influence acceptance and 3) to explore if fat acceptance can be related to inter-individual differences in salivary compounds potentially involved in fat perception. Twenty six infants with contrasted milk feeding history participated and were introduced with complementary foods at 4.8 months. During the 1st month of complementary feeding, acceptance of 3 broccoli purees (0% fat, 7% of vegetable oils, 7% of dairy fat) was determined through ad libitum intake and global liking, in the laboratory and at home. Saliva was collected: lipolytic activity and carbonic anhydrase 6 concentration were determined. Puree intakes were not impacted by fat addition, whatever the type of added fat. Moreover, the history of milk feeding (breast milk vs. vegetable oils based formulas) in the very first months did not explain acceptance for added fat. Finally, no links between intake and saliva composition were evidenced. Altogether, this study found that the addition of fat did not modify food acceptance by infants during early complementary feeding. Thus, future research should investigate the development of fat acceptance over experience in early infancy.

Characterization of pectins extracted from pomegranate peel and their gelling properties.

The composition of pomegranate peel, the main by-product during pomegranate processing, and some of the characteristics of the water-soluble pectins were investigated. Four tunisian pomegranate peels were subjected to hot aqueous extractions (86°C, 80min, 20mM nitric acid). Pomegranate peels yielded between 6.8% and 10.1% pectins. The extracted pectins were low methylated and were characterized by the predominance of homogalacturonan regions. Principal component analysis applied on FT-IR spectral data in the region between 4000 and 650cm(-1) differentiated the samples according to their degree of methylation. At pH 3, in the presence of 0.7% pectin, all solutions showed a rapid gel formation with G'>G″. With decreasing temperature from 90°C to 10°C, G' increased to reach a plateau at 10°C. The variation in the pectin gel formation between varieties was attributed to difference in pectin characteristics particularly the hydrodynamic volume and the neutral sugar content.

A photographic method to measure food item intake. Validation in geriatric institutions.

From both a clinical and research perspective, measuring food intake is an important issue in geriatric institutions. However, weighing food in this context can be complex, particularly when the items remaining on a plate (side dish, meat or fish and sauce) need to be weighed separately following consumption. A method based on photography that involves taking photographs after a meal to determine food intake consequently seems to be a good alternative. This method enables the storage of raw data so that unhurried analyses can be performed to distinguish the food items present in the images. Therefore, the aim of this paper was to validate a photographic method to measure food intake in terms of differentiating food item intake in the context of a geriatric institution. Sixty-six elderly residents took part in this study, which was performed in four French nursing homes. Four dishes of standardized portions were offered to the residents during 16 different lunchtimes. Three non-trained assessors then independently estimated both the total and specific food item intakes of the participants using images of their plates taken after the meal (photographic method) and a reference image of one plate taken before the meal. Total food intakes were also recorded by weighing the food. To test the reliability of the photographic method, agreements between different assessors and agreements among various estimates made by the same assessor were evaluated. To test the accuracy and specificity of this method, food intake estimates for the four dishes were compared with the food intakes determined using the weighed food method. To illustrate the added value of the photographic method, food consumption differences between the dishes were explained by investigating the intakes of specific food items. Although they were not specifically trained for this purpose, the results demonstrated that the assessor estimates agreed between assessors and among various estimates made by the same assessor. The results also revealed that the accuracy of this method was not dependent on the type of food studied, thus, the photographic method was not specific to a particular food type. Finally, the photographic method was able to provide more detailed data because it allowed differentiation between food item intakes. These findings clearly suggest that the photographic method is a valid and useful method to measure food intake in geriatric institutions.

Effects of pH and oil-in-water emulsions on growth and physicochemical cell surface properties of Listeria monocytogenes: Impact on tolerance to the bactericidal activity of disinfectants.

This study characterizes the effects of an acidic pH and an emulsified oil-in-water phase in a culture medium on the behavior of Listeria monocytogenes. Two strains were tested, Scott A and CIP 78.39, and exhibited similar responses to growth media. First of all, the results showed that the emulsified oil phase had no effect on growth kinetics, whereas acidification of the initial pH (from 7.2 to 5.2) reduced both growth rates and growth yields. Secondly, physicochemical cell surface properties were evaluated. Growth in an emulsion resulted in a more marked increase in hydrophobicity in neutral than in acidic media, whereas the electrical charge remained unchanged. Furthermore, growth in acidic media - emulsified or not - induced a reduction in hydrophobicity as well as in the negative charge of cell surfaces. Thirdly, the results showed that tolerance to the bactericidal activity of didecyl dimethyl ammonium bromide (DDAB) and sodium dichloroisocyanuric acid (NaDCC) was strongly dependent on the pH of the growth phase. Acidic stress during growth increased tolerance to both disinfectants, but to a greater extent with DDAB than with NaDCC. Moreover, the presence of an emulsion during growth at an acidic pH had no effect on subsequent strain tolerance to disinfectants. By contrast, when the pH of the emulsion was neutral, the oil phase induced a more marked reduction in the tolerance of both strains to DDAB, but the reverse applied with NaDCC. Taken together, these results indicate a clear link between modifications to cell surface properties and tolerance to disinfectants, related to the hydrophobicity and electrical charges of both bacterial cells and disinfectants.

Heat-induced gelation of porcine blood plasma proteins as affected by pH.

Porcine plasma is a by-product of the meat industry that can be used as a food ingredient. It is a protein mixture, hence its composition can be modified to meet specific functionality requirements. In the present paper, the gelation properties of plasma and its two major fractions (serum and albumin) have been studied at pH 4.5, 6.0 and 7.5. Polyacrylamide gel electrophoresis (SDS-PAGE) revealed that albumin was the constituent that remained soluble to a larger extent during heat-treatments, and that acidic coagulation occurred at pH 4.5, making weak interactions the predominating ones between protein aggregates. Differential scanning calorimetry (DSC) and rheological tests showed that both the thermal stability and the gelation point of protein solutions were lower as pH decreased. The textural properties and water-holding capacities of plasma and albumin gels were more pH-dependent than serum. Albumin gels were the weakest and those of plasma at pH 7.5, the strongest. It has been determined that interactions between protein fractions play a key role in the gelling properties due to synergistic effects. This knowledge should be useful in the engineering of a plasma derivative product designed for specific food requirements, by reformulating its natural composition and enhanced by controlling pH.