Development of Protein- and Fiber-Enriched, Sugar-Free Lentil Cookies: Impact of Whey Protein, Inulin, and Xylitol on Physical, Textural, and Sensory Characteristics.

Gluten-free (GF) diets often become nutritionally imbalanced, being low in proteins and fibers and high in sugars. Preparing GF foods with improved nutritional value is therefore a key challenge. This study investigates the impact of different combinations of whey protein (11.9%), inulin (6.0%) as dietary fiber, and xylitol (27.9%) as a sweetener used in the enrichment of green- and red-lentil-based gluten-free cookies. The cookies were characterized in terms of baking loss, geometric parameters, color, texture, and sensory profile. The results showed that these functional ingredients had different impacts on the lentil cookies made of different (green/red) lentils, especially regarding the effect of fiber and xylitol on the volume (green lentil cookies enriched with fiber: 16.5 cm3, sweetened with xylitol: 10.9 cm3 vs. 21.2 cm3 for control; red lentil cookies enriched with fiber: 21.9 cm3, sweetened with xylitol: 21.1 cm3 vs. 21.8 cm3 for control) and color (e.g., b* for green lentil cookies enriched with fiber: 13.13, sweetened with xylitol: 8.15 vs. 16.24 for control; b* for red lentil cookies enriched with fiber: 26.09, sweetened with xylitol: 32.29 vs. 28.17 for control). Regarding the textural attributes, the same tendencies were observed for both lentil products, i.e., softer cookies were obtained upon xylitol and whey protein addition, while hardness increased upon inulin enrichment. Stickiness was differently influenced by the functional ingredients in the case of green and red lentil cookies, but all the xylitol-containing cookies were less crumbly than the controls. The interactions of the functional ingredients were revealed in terms of all the properties investigated. Sensory analysis showed that the addition of whey protein resulted in less intensive "lentil" and "baked" aromas (mostly for red lentil cookies), and replacement of sugar by xylitol resulted in crumblier and less hard and crunchier products. The application of different functional ingredients in the enrichment of lentil-based gluten-free cookies revealed several interactions. These findings could serve as a starting point for future research and development of functional GF products.

Lentil (Lens culinaris Medik.) Flour Varieties as Promising New Ingredients for Gluten-Free Cookies.

Monotony in a gluten-free (GF) diet can be a challenge because of a limited choice of acceptable cereal sources. This study investigates the potential of five types of differently coloured lentils in the development of GF cookies using rice flour as a reference. Raw materials (lentil flours) and cookies were characterised in terms of physicochemical parameters (e.g., crude protein content, total phenolics and flavonoids, antioxidant properties, colour, pH); additionally, geometry, baking loss and texture profile were determined for the cookies. A sensory acceptance test was also conducted to find out consumer preferences regarding rice versus different lentil cookies. Results showed that lentil cookies were superior to rice control in terms of higher crude protein (12.1−14.8 vs. 3.8 g/100 g), phenolic (136.5−342.3 vs. 61.5 mg gallic acid equivalents/100 g) and flavonoid (23.8−75.9 vs. 13.1 mg catechin equivalents/100 g) content and antioxidant capacity (0.60−1.81 vs. 0.35 mmol trolox equivalents/100 g), as well as lower hydroxymethyl-furfural content (<1 vs. 26.2 mg/kg). Consumers preferred lentil cookies to rice ones (overall liking: 6.1−7.0 vs. 5.6, significant differences for red and brown lentils), liking especially their taste (6.3−7.0 vs. 5.5). Depending on the target parameter, whether physicochemical or sensory, these lentil flours can be promising raw materials for GF bakery products.

Characterisation and comparison of selected wheat (Triticum aestivum L.) cultivars and their blends to develop a gluten reference material.

The reliability and comparability of gluten analytical results in gluten-free foods is hampered by the lack of reference materials (RM). This is partly caused by the yet incomplete knowledge of the effect of genetic and environmental variability of wheat proteins on immunochemical analyses, which affects the choice of gluten source to be applied for RM production. We investigated the genetic variability and the effect of harvest year on the protein composition of five previously selected wheat cultivars. We also compared the magnitude of these effects on ELISA results to get closer to the question of choosing individual cultivar or a mixture as an RM. Our results proved that the application of a blend for this purpose is advantageous. The candidates were also produced on pilot scale to investigate the feasibility of upscaling. The results of comparison studies showed that the pilot scale blended flour can also be suitable for RM.

Variation in protein composition among wheat (Triticum aestivum L.) cultivars to identify cultivars suitable as reference material for wheat gluten analysis.

Gluten proteins of certain cereals (wheat, rye and barley) can trigger hypersensitivity reactions. In special dietary products for people intolerant to gluten, their amount must not exceed the regulatory threshold levels. The source of gluten can influence gluten quantitation due to variability in protein profile of grain cultivars and species. A proper reference material is crucial for accurate measurement of gluten and evaluating assay performance. It should be as representative of the commodity as possible. In this study, protein content and composition of a set of 23 common wheat cultivars grown around the world were determined. According to qualitative and quantitative selection criteria, cultivars that possessed a typical gluten composition were identified. Five cultivars were selected for subsequent experiments to confirm their suitability as a basis for reference material production.

Development of incurred reference material for improving conditions of gluten quantification.

Celiac disease and wheat allergy are the most common adverse reactions triggered by cereal proteins, mainly gluten, which is one of the 14 allergenic food ingredients that must be labeled on food products in the European Union (EU). To meet the requirements of this regulation, reliable analytical methodology for proper quantification of gluten is necessary. However, validation of presently used methods (ELISA and lateral flow device) is limited partly due to the lack of reference methods and incurred reference materials. To solve this problem, the goal of our work was to develop an incurred reference material for the quantification of gluten under the auspices of EU-FP6 funded Network of Excellence MoniQA. During this work, we produced a processed model product (cookie) containing gliadin (major allergenic fraction of gluten) in a defined amount. This paper addresses the development process of this material together with the associated problems (insufficient homogeneity and low recovery) and their solutions. As a result, an incurred food matrix was produced on a laboratory-scale with a potential use as a reference material. The model product was tested by an ELISA method followed by a comparative study of commercially available ELISA kits to investigate the applicability of the product. Preliminary results of this study are also presented.

Towards development of incurred materials for quality assurance purposes in the analysis of food allergens.

Food allergy and intolerance became very important problems in food safety and healthcare during the last few decades. Beside the pharmaceutical treatment of the symptoms, effective cure of these illnesses is the avoidance of the problematic food proteins. According to this reason, proper legislation is crucial for protecting sensitive people. In the European Union 14 allergenic components must be labelled which requires introduction of properly validated analytical methods for the appropriate quantification of allergenic proteins. The aim of our work is studying such parameters which may affect the analytical results, therefore have to be taken into account during the validation process. For investigating these issues, an incurred sample matrix was produced, namely a wheat flour based cookie, which contains allergenic proteins (milk or egg) in a dedicated amount. Using these samples the effects of food processing steps and the analytical performance of the applied Enzyme-Linked Immunosorbent Assay (ELISA) methods were studied. A major finding of our work is that heat treatment caused a large-scale decrease in the amount of measurable allergen content of the samples. The background of this phenomenon has not been clarified yet. Besides, the gathered data indicates that the performance of the ELISA method is highly related to the state of the sample matrix. These problems altogether must be taken into consideration for making a proper validation protocol and revealing their background also has a great importance in further evaluation of the analytical methods.