Physicochemical and Antioxidant Properties of Wheat Bread Enriched with Hazelnuts and Walnuts

Sensory optimization of gluten-free hazelnut omelette and sugar-modified chestnut pudding: A free choice profiling approach for enhanced traditional recipe formulations

The Mediterranean region is distinguished by its gastronomic diversity and a wide variety of indigenous nut crops. In line with changing global food consumers' preferences, a noteworthy aspect is the increasing demand to the use of local varieties in recipe formulation. The aim of the present study was to incorporate the Terra Fria chestnut (Portugal) and Negreta hazelnut from Reus (Spain) in traditional Mediterranean recipes. The sensory, technofunctional, nutritional, and shelf-life characterization were investigated in hazelnut omelette (gluten and gluten-free) and chestnut pudding (sugar and sugar-free) formulations. Results conducted by trained assessors using the free choice profiling (FCP) showed that hazelnut omelette samples were described as "creamy," "smooth," and "handmade." In addition, the texture obtained with the hazelnut omelette gluten-free version showed the softest textural profile analysis attributes, with lower values for hardness (2.43 ± 0.36 N), adhesiveness (-0.38 ± 0.00 g s) and gumminess (2.12 ± 0.14). Furthermore, the shelf-life studies revealed a more golden color (>14.43 of a* CIELAB coordinate) and a lower moisture content (25.36%-43.59%) in the hazelnut flour formulation, in addition to the enrichment in terms of protein (8.36 g/100 g), fiber, and healthy fats. In the case of chestnut pudding, it was observed that the study parameters did not differ significantly from its sweetened analogue with positive attributes in FCP ("toasted," "fluffy," and "sweet"), positioning it as a viable alternative to sugar in this application. Therefore, both hazelnut flour in hazelnut omelette and oligofructose in chestnut pudding proved to be promising ingredients in the formulation of gluten-free and sugar-free developed products, offering attractive organoleptic and textural characteristics.

Influence of sesame cake on physicochemical, antioxidant and sensorial characteristics of fortified wheat breads

Incorporation of two sesame cake preparations, differing in fat, 11 % (LF) and 17 % (HF), and protein, 51 % (LF) and 44 % (HF), contents, respectively, into breads at 6, 12 and 20 % wheat flour substitution levels, led to enriched end-products with antioxidants, suitable also to carry the 'high protein' and 'fiber source' nutrition claims (at ≥ 12 % substitution level). Sesame cake decreased wheat dough resistance to mixing and extension, and peak viscosity (empirical rheology), in a concentration-dependent manner, being more pronounced for LF formulations. Breads with LF incorporation ≥ 12 % had lower specific volumes and harder crumb (texture analysis) throughout storage, than control (100 % wheat flour); however, such adverse effects were diminished in HF bread formulations due to the plasticizing and emulsifying action of the sesame cake fat. Calorimetry showed that the sesame cake had no effect on starch retrogradation, but enhanced amylose-lipid complex formation. Antioxidant activity (ABTS, DPPH and FRAP assays), and phenolic acids (ferulic, p-coumaric and sinapic) and lignan (sesaminol glucosides and sesamolin) contents, determined by HPLC-DAD-MS, were higher in LF breads than their HF counterparts. The presence of some sulfur (off-flavor) and pyrazine (nutty flavor) compounds (SPME-GC-MS), as well as the sesame flavor and bitterness (sensory analysis) were of higher intensity in HF breads, while the 6 % LF product received the highest overall acceptability score among all fortified products. Overall, the sesame cake can be a promising ingredient for production of functional wheat bread depending on its composition and fortification level.

Walnut Flour as an Ingredient for Producing Low-Carbohydrate Bread: Physicochemical, Sensory, and Spectroscopic Characteristics

Walnut flour (WF) is a nutrient-rich source that can be used as an alternative for individuals on a gluten-free diet. This study aimed to assess the physical, chemical, and sensory changes in low-carbohydrate bread when supplemented with WF. Molecular-level changes were also examined using ATR-FTIR spectra. The bread recipe, containing buckwheat and flaxseed, was enriched with WF at levels ranging from 5% to 20%. The addition of WF resulted in increased loaf volume and decreased baking loss. Enriched bread samples showed higher protein content, while fat and available carbohydrate content decreased. Additionally, WF incorporation led to a decrease in crumb brightness and an increase in redness (from 23.1 to 25.4) and yellowness (from 23.8 to 26.7). WF also increased crumb hardness and chewiness. Moreover, the tested additives primarily influenced the intensity of FTIR spectra, indicating changes in protein, carbohydrate, and fat content, with increased band intensity observed in the protein region. We particularly recommend bread with a WF content of 15%. This type of bread is characterized by high consumer acceptance. Furthermore, compared to bread without the addition of WF, it has a higher content of phenolic compounds, protein, and fat by approximately 40%, 8%, and 4%, respectively. The antioxidant activity of this bread, determined using the ABTS and DPPH methods, is also significantly higher compared to the control bread.

Saffron Floral By-Products as Novel Sustainable Vegan Ingredients for the Functional and Nutritional Improvement of Traditional Wheat and Spelt Breads

Saffron (Crocus sativus L.) is a traditional Mediterranean plant whose stigmas are used to obtain the most expensive spice in the world. Nevertheless, there is a lack of sustainability in its production, since, to produce 1 kg of saffron, about 350 kg of tepals are discarded. Therefore, this study aimed to develop wheat and spelt breads enriched with saffron floral by-products at a ratio of 0, 2.5, 5, and 10% (w/w), respectively, and to evaluate their nutritional, physicochemical, functional, and sensory properties, as well as the stability of antioxidant compounds during the in vitro digestion. The results revealed that the addition of saffron floral by-products, especially at 10%, increased the dietary fiber content by 25-30% of traditional wheat and spelt breads; improved their mineral content (270-290 mg/100 g for K, 90-95 mg/100 g for Ca, 40-50 mg/100 g for Mg, and 15-18 mg/100 g for Fe); changed their textural properties; and significantly enhanced the phenolic content and antioxidant ability (at 5 and 10%), which remained stable throughout the in vitro oral and gastrointestinal digestion processes. From a sensory point of view, the addition of saffron flowers modified the organoleptic properties of breads. Thus, these novel vegan enriched breads could exert beneficial effects on human health after their intake, making saffron floral by-products suitable and sustainable ingredients to develop new functional foods such as healthier alternative vegan bakery products.

Comparison of the Rheological Behavior of Fortified Rye-Wheat Dough with Buckwheat, Beetroot and Flax Fiber Powders and Their Effect on the Final Product

This study was focused on the replacement of the part of the flour (10% w/w) in rye-wheat bread with three different botanical origin powders with a high dietary fiber content (buckwheat hulls, beetroot and flax powder). The dough was based on rye-wheat flour without and with the addition of fiber powders with different botanical origins and was tested, and the quality of the finished baked products made from those doughs were assessed. In order to characterize the flour mixtures, their basic parameters were determined, and their pasting characteristic was performed. The dough parameters were described by the Burger rheological model and also the creep and recovery test. On the other hand, in bread, the basic parameters of baking, crumb and crust color parameters were determined, and an analysis of the crumb texture was carried out. Additionally, a sensory analysis of the finished products was carried out. The applied fiber additives influenced the pasting characteristics of the tested rye-wheat flour and were influenced by the dough rheological properties. It was found that used fiber powders changed the quality parameters of the final products. Despite this, using fiber at the amount of 10% as a flour substitute allowed us to obtain bread of a similar quality to the control sample.

Walnut Male Flowers (Juglans regia L.) as a Functional Addition to Wheat Bread

The aim of this study is to assess the effect of adding dried and ground walnut male flowers to wheat flour on selected physicochemical and antioxidant properties of the obtained wheat bread. The control sample was bread without the addition of walnut male flowers. In the tests, the addition of flowers was used in the amounts of 0.5%, 1.0%, 1.5%, 2.0% and 2.5% of the weight of the flour used in the control sample. Bread dough was prepared according to the direct method with the use of yeast. The parameters of the baking process of the control bread and of the test bread were calculated. The selected parameters determining the quality of the obtained bread, including the loaf volume, the specific volume, the crumb porosity, the crumb texture and the color were measured. The antioxidant potential and total polyphenol content were tested both in the dough and in the bread. The test results were analyzed statistically. It was found that the partial replacement of wheat flour with walnut male flowers resulted in a significant reduction in the loaves' volume and in the darkening of both the color of the dough and the crumb. The value of the L* parameter decreased with the increasing addition of walnut flowers. The lowest values of this parameter were found to be 53.87 (crust) and 39.94 (crumb) in the sample with 2.5% addition. The average volume of the loaves ranged from 565 cm³ (0.5%) to 675 cm³ (control). The use of the additive in the amount of 2.5% caused significant changes in the values of most of the examined parameters of the bread crumb texture. The addition of walnut male flowers to the flour had a significant effect on the antioxidant potential and the total polyphenol content of the tested doughs and breads. In the case of bread, the total polyphenol content value ranged from 96.90 mg GAE/g dw to 208.08 mg GAE/g dw. Similarly, the antioxidant potential increased with increasing walnut male flower supplementation. The antioxidant potential determined by the ABTS and FRAP methods ranged from 1.42 mmol TE/g dw to 2.02 mmol TE/g dw and from 0.08 mmol TE/g dw to 0.33 mmol TE/g dw, respectively. The obtained research results prove the application potential of walnut flowers in the design of food, with beneficial pro-health properties, and are an example of the use of plant by-products in the process of food enrichment.

Biological Characterization and Quantification of Rambutan (Nephelium lappaceum L.) Peel Extract as a Potential Source of Valuable Minerals and Ellagitannins for Industrial Applications

This study extracted ellagitannins from rambutan peel using the Soxhlet technique. The extract was further partitioned and fractionated to get extract rich in ellagitannin and geraniin, respectively. The partitioning of the extract significantly increased total phenolic content (TPC) by 36.3% and its biological properties. Mineral elements such as Ca, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, and Zn were identified in both peel and extract. Ellagitannins such as geraniin and corilagin with metabolites (gallic acid and ellagic acid) were identified as the major compounds. Analysis of antioxidant activities shows that the ellagitannin rich extract is as powerful as vitamin C. Geraniin was the main contributor to the free radical scavenging activity. The study also revealed that extract with a fraction rich in geraniin has antioxidant activity equivalent to commercial geraniin (1.56 ± 0.11 Trolox equivalent g/g). It also showed low cytotoxicity on fibroblast L929 cells, moderate tyrosinase activity, and good efficacy against Staphylococcus aureus, Staphylococcus epidermidis, and Cutibacterium acnes strains. Successive fractionation of the extract is a promising technique to produce geraniin rich fractions with enhanced antioxidant property. Rambutan peel, as a natural product, is a good source of mineral elements and biologically active compounds for pharmaceutical, nutraceutical, and cosmetic formulations.

Addition of phenolic compounds to bread: antioxidant benefits and impact on food structure and sensory characteristics

The use of flours or phenolic extracts obtained from non-traditional sources or agri-food industry by-products has been a strategy used to formulate new bakery products with characteristics of a functional food. However, phenolic compounds present great structural diversity, as well as the ability to interact in a complex way with the macromolecules that constitute the bread matrix. Therefore, the addition of these flours, extracts or pure compounds produces various effects on the microstructure of bread, and several of its sensory properties. This is mainly due to interactions between phenolic compounds and gluten proteins. The objective of this review is to analyze some of the most recent published works on the addition of phenolic compounds in wheat bread to identify the type of positive and negative effects that have been observed and how they can be related to the physicochemical interactions between phenolic compounds and the macromolecules that constitute the food matrix, mainly gluten. The effect of monomeric and polymeric phenolic compounds on the strength of these interactions and on the properties of dough and bread are discussed.

Graphical Abstract

Antioxidative Characteristics and Sensory Acceptability of Bread Substituted with Purple Yam (Dioscorea alata L.)

In this study, plain bread was made by substituting wheat flour with purple yam flour (Dioscorea alata, L). The addition of 0, 10, 15, 20, and 30% purple yam flour aims to increase the functional value of plain bread as a source of natural antioxidants. The bread produced with two baking temperatures (170°C and 180°C) was tested for anthocyanin levels, total phenol, antioxidant activity (DPPH free radical scavenging), volume expansion, color, and preference test. The results showed that the temperatures of the bread baking did not affect anthocyanin levels, total phenol, antioxidant activity, volume expansion, and bread color (p > 0.05). The substitution of purple yam flour had a significant effect on anthocyanin levels, total phenol, antioxidant activity, volume, and bread color (p < 0.05). The levels of anthocyanins, total phenol, antioxidant activity, and darker color increased with the addition of purple yam flower whereas the rate of expansion reduced. However, the addition of purple yam flour did not affect the level of preference for the bread produced. Purple yam flour can be added to the manufacture of bread made from wheat flour as much as 30% with a baking temperature of 180°C. The resulting bread contained total anthocyanins 54.62 mg/100 g db, total phenol 391.14 mg EAG/100 g db, antioxidant activity 48.53% and volume expansion 64.85%, color L^∗ = 53.06, a^∗ = 6.52, b^∗ = 13.32, C = 14.87, H = 64.06, and sensory score = 3.24 (preferred).

The Influence of the Addition of Nuts on the Thermal and Rheological Properties of Wheat Flour

The aim of the study was to assess the influence of replacing wheat flour with hazelnuts or walnuts, in various amounts, on the thermal and rheological properties of the obtained systems. The research material were systems in which wheat flour was replaced with ground hazelnuts (H) or walnuts (W) in the amount of 5%, 10%, and 15%. The parameters of the thermodynamic gelatinization characteristics were determined by the differential scanning calorimetry method. In addition, the pasting characteristics were determined with the use of a viscosity analyzer and the viscoelastic properties were assessed. Sweep frequency and creep and recovery tests were used to assess the viscoelastic properties of the tested gels. It was found that replacing wheat flour with nuts increased the values of gelatinization temperature, gelatinization, and retrogradation enthalpy, and the degree of retrogradation. The highest viscosity was characteristic of the control sample (2039 mPa·s), and the lowest for the paste with 15% addition of walnuts (1120 mPa·s). Replacing the flour with nuts resulted in a very visible reduction in the viscosity of such systems. In addition, gels based on the systems with the addition of H and W were weak gels (tan δ = G″/G' > 0.1), and the values of G' and G″ parameters decreased with the increased share of nuts in the systems. Creep and recovery analysis indicated that the systems in which wheat flour was replaced with hazelnuts were less susceptible to deformation compared to the systems with the addition of W.

The Influence of Hypericum perforatum L. Addition to Wheat Cookies on Their Antioxidant, Anti-Metabolic Syndrome, and Antimicrobial Properties

The aim of this study was to characterize wheat cookies enriched with 0.5% and 1.0% of Hypericum perforatum L. (St. John's wort, SJW) and determine their pro-health properties in vitro after hydrolysis in simulated gastrointestinal conditions. The results indicated that 1.0 SJW was characterized by the highest content of polyphenols, flavonoids, and phenolic acids (2.32 mg mL-1, 4.93 µg mL-1, and 12.35 µg mL-1, respectively). The enriching cookies had no effect on water absorption capacity (WAC) and oil absorption capacity (OAC). After in vitro hydrolysis, the highest peptide content was noted in 1.0 SJW (0.52 mg mL-1), and the bioactive compounds were characterized by high potential bioaccessibility (PAC), but poor bioavailability (PAV). The addition of SJW increased the ACE, α-amylase, and LOX inhibitory effect, but reduced the inhibition of pancreatic lipase. The highest antioxidant activity was noted for 1.0 SJW. The results showed that only 0.5 SJW and 1.0 SJW had slight antimicrobial activity against E. coli ATCC 25922 and B. cereus ATCC 14579 with MIC = 12.5 mg mL-1. Fractions with molecular mass <3.0 kDa were characterized with the highest p-coumaric acid content. The results show that SJW cookies had a higher content of bioactive compounds and more potent anti-metabolic syndrome effects.

A Review of Registered Clinical Trials on Dietary (Poly)Phenols: Past Efforts and Possible Future Directions

In recent years, the increasing number of studies on polyphenol demonstrates the efforts in elucidating the potential role of these bioactives on human health. This study reviews the main topics and characteristics of clinical trials on polyphenols registered over the last 20 years, in order to track past and current efforts as well as to highlight the main research gaps in this field. The review was conducted by collecting trials registered in ClinicalTrials.gov and International Standard Randomised Controlled Trial Number (ISRCTN) registry. Overall, 750 clinical trials were selected and included in the final evaluation. Most of the trials were performed on extracts or pure compounds followed by studies conducted on polyphenol-rich foods, in particular berries. A total of 520 clinical trials focused on health effects, 55 on bioavailability, and 175 on both. Regarding outcomes, 139 registered intervention studies had the lipid profile and blood pressure as primary outcomes. The overview provided by this analysis also emphasizes the emerging interest in new outcomes related to polyphenols intervention such as microbiota composition and the evaluation of inter-individual variability in response to the intake of polyphenols. Our review underlines the need of further trials covering unexplored or debated research aspects and provides insights for the design and development of future intervention studies and related research areas.