Gluten-Free Crackers Based on Chickpea and Pumpkin Seed Press Cake Flour: Nutritional, Functional and Sensory Properties

Research background

Despite the growing trend of the gluten-free market and the presence of a wide range of gluten-free products, there are still some shortcomings in nutritional and sensory quality of these products. The commercially available gluten-free products are characterised as products of inferior nutritional quality, particularly in terms of protein and dietary fibre content and with high glycaemic index. On the other hand, from a sensory point of view, gluten-free products usually have inappropriate textural and mechanical properties, poor mouthfeel and flavour. This is a consequence of the limiting choice of raw materials that mainly possess large amount of carbohydrate components.

Experimental approach

Chickpea flour and two types of pumpkin seed press cake flour (virgin and cold pressed), at two substitution mass fractions (20 and 35%), were blended to produce gluten-free crackers without the presence of conventional gluten-free starch-rich ingredients. This study aims to investigate the effect of these non-conventional flours on nutritional and physicochemical properties, sensory acceptability, antioxidant activity and glycaemic index of crackers.

Results and conclusions

All produced crackers can bear nutritional claims 'high fibre', 'source of protein' and 'source of minerals'. Replacing chickpea flour with pumpkin seed press cake flour increased protein and total phenolic content and enhanced antioxidant activity. The selected combination of raw materials allows the production of gluten-free crackers with a moderate glycaemic index. Besides nutrient content, the addition of cold-pressed flour increased overall sensory acceptability, noticeably improving taste and flavour scores compared to the control and crackers with virgin pumpkin seed flour.

Novelty and scientific contribution

To the best of our knowledge, there is no study investigating the use of chickpea and pumpkin seed press cake flour blend without using conventional gluten-free flour and starch. The used non-conventional flour represents complementary raw materials in terms of protein quality and valuable alternatives to produce nutrient-rich, health-promoting gluten-free crackers with reduced glycaemic response and acceptable sensory properties.

Vegetable By-Products as New Sources of Functional Proteins

Vegetable by-products, obtained from cauliflower (CA), broccoli (BRL), cabbage (CB) and beetroot (BR) can be a potentially good source of proteins. The proteins were obtained from leaves (LPs) of vegetables with alkaline extraction at pH 10, and their isoelectric precipitation at pH 4. Protein contents were in the range of 39.76 - 53.33%, and the molecular weights of fractions were mostly about 45, 25 and 14 kDa. Their solubility is higher in the alkaline environment, where they reach the highest solubility at pH 10 (9.7 mg/mL for CALP, 8.45 for BRLP, 5.35 mg/mL for CBLP, 5.5 mg/mL for BELP). Moreover, they showed favorable emulsifying abilities, water absorption capacities (0.62 to 1.61 g/g) and foaming capacity (86.3 to 92%) as well as stability (48.57 to 79.30%). Digestibility was studied using gastrointestinal proteases (pepsin and pancreatin), and all four LPs can easily be digested. The biologically active potential of the digests was evaluated measuring antioxidant capacity by two complementary methods - DPPH⁺ and ABTS⁺ radical cation scavenging activity. The values for DPPH+ and ABTS+ were in the range from 59 to 65.1% at 0.1 and 0.3 mg/ml to 0.22 mg/ml IC₅₀ values, respectively. Therefore, it can be indicated from these results, that obtained LPs, owing to their good functional properties, may be considered as potential ingredients of health-promoting food and cosmetic products.

Comparative study of nutritional and technological quality aspects of minor cereals

In order to have a better insight into the quality of minor cereals, the aim of this research was to evaluate the nutritional, biochemical, physical and rheological properties of barley, rye, triticale, oat, sorghum and millet flours. Generally, all flours could be divided into two groups according to mineral content, ω-6/ω-3 fatty acids ratio and amino acid composition. Sorghum flour was characterized by the highest total phenolic content and was the only flour which contained detectable amounts of tannins. Sorghum and millet flours differed from other flours by lower water absorption index and higher temperature of starch gelatinization. Additionally, sorghum and millet flours could be analysed by Mixolab only using constant hydration and require more time to obtain complete hydration than other flours. All flours would require modification of standard breadmaking process in order to obtain quality of product similar to those already present at the market.

Determination of protein oxidation in aquaculture feed

This research aimed to develop a reliable, easy-to-perform and cheap method for measuring protein oxidation in complex samples such as aquaculture feed within various protein sources. For that purpose modified 2,4-dinitrophenylhydrazine (DNPH)-based method for quantification of protein carbonyls was employed whilst the modification of the method consisted of using different solutions for the extraction (distilled water and different concentrations of KCl and NaCl solutions), time of protein extraction (after homogenization and over the night) and concentration of trichloroacetic acid (10 and 25% TCA) for protein precipitation. Extraction during the night, higher TCA concentration and the use of 0.5 M KCl extraction solution resulted in the highest protein amount measured by the Lowry method and 280 nm protein estimation. On the other hand, the lowest protein yield was obtained by using distilled water for the extraction. Furthermore, the lowest amount of protein carbonyls was in the case when extraction was performed with distilled water (DW), while the highest content of protein carbonyls was reached with 0.15 M KCl and 0.5 M KCl extraction solutions. It was observed that the amount of proteinbound carbonyls compounds was increasing during storage under accelerated conditions and, in comparison to the original method, the modified method for measuring protein oxidation resulted in a higher amount of carbonyls during all points of storage.

Production of Bio-Functional Protein through Revalorization of Apricot Kernel Cake

The study describes and compares bio-functional properties and thein vitrodigestibility of protein isolates from apricot oil cakes obtained by supercritical fluid extraction and cold pressing, as control. Protein isolates have the potential to be food ingredients with amygdalin contents in an amount considerably lower than regulatory. Isolates showed hypoglycemic activity, studied by the inhibition of α-glucosidase, also functional properties were determined.Good digestibility of proteins, which were done using gastrointestinal proteases (pepsin and pancreatin) were proven by Sodium Dodecyl Sulfate Polyacrylamide Gel Electrophoresis SDS-PAGE analysis. Moreover, it was evident that the protein isolates were completely digested. The biologically active potential of the digests was evaluated measuring in vitro antioxidant capacity by three complementary methods and enzyme inhibitory effects towards Angiotensin-I Converting Enzyme (ACE) related with the onset of hypertension. All hydrolysates act as a DPPH and ABTS scavenger, as a reducing agents and an ACE enzyme inhibitor. In conclusion, protein isolates obtained from apricot kernel cake showed to be a promising source of natural products for food applications, with good functional and bioactive properties and easy digestibility.

Subcritical Water for Recovery of Polyphenols from Comfrey Root and Biological Activities of Extracts

In the present study, subcritical water was used for extraction of bioactive compounds of Symphytum officinale root. Temperature (120-200 °C), extraction time (10-30 min) and HCl concentration in extraction solvent (0-1.5%) were investigated as independent variables in order to obtain the optimal conditions for extraction and to maximize the yield of total phenols, flavonoids and antioxidant activity of obtained extracts. The application of optimal conditions (200 °C, 25.6 min and 0.0075%) provided extracts rich in total phenols and flavonoids and high antioxidant activity. Results also demonstrated that subcritical water extraction showed significant advantages for recovery of comfrey root bioactive compounds comparing to maceration and ultrasound-assisted extraction techniques. In addition, subcritical water extracts of S. officinale root are the promising sources of compounds with antioxidant, ACE inhibition, and antiproliferative properties and could potentially be used for production of new pharmacologically-active formulations.