Millet is an unexploited cereal with potential in the food industry due to its nutritional value and resistance to harsh climate conditions. Nutritious millet byproducts have a potential application ...in the development of functional cereal products, but require processing in order to improve their physical and nutritional quality. Therefore, we investigated high intensity ultrasound as a pretreatment to increase the amount of freely available bioactives from proso millet bran. We also analysed the effect of high intensity ultrasound on enzymatic browning, water retention and protein digestibility, which are crucial for the utilization in the bakery and pasta industry. A 15 % millet bran suspension in water was treated with 400-W ultrasound probe for 5, 12.5 or 20 min, with the 60, 80 or 100 % amplitude. High intensity ultrasound treatment with 80 % amplitude for 12.5 min improved most significantly the nutritive value; the antioxidant activity measured by FRAP test increased by 15 % (p<0.05), and total phenolic content by 16 % (p<0.05). Still, the impact on the increase of water-soluble and ethanol-insoluble dietary fibre by 38 % was evident after the treatment for 20 min at 100 % amplitude. High intensity ultrasound treatment at 100 % amplitude for 5 min caused the largest improvements in water retention and limited browning of the sample. High intensity ultrasound treatment activated polyphenol oxidase, regardless of the applied heating of the sample. Due to its ambiguous impact on proso millet bran characteristics, the treatment required an optimization, which showed that the optimal pretreatment of a 15 % millet bran suspension in water is at 100 % amplitude for 9.3 min.
3D printing is an emerging technology that offers the ability to produce tailor-made foods. This work addresses the physical properties of 3D-printed snacks enriched with wheat bran as a function of ...flour type (oat, barley), addition of acidity regulators (citric acid, sodium bicarbonate), printing temperature (20 °C, 30 °C, 40 °C), and bran pre-processing (high-intensity ultrasound, vacuum microwave and pulsed light). Polyphenol oxidase activity, total phenolic content, antioxidant activity of bran, the viscosity profile of the flour-bran blend, the precision of 3D printing and browning kinetics of the physical properties of the dough and of baked snacks were investigated. During 1 h required to print ten pieces, the dough became very distinctly darker. Adjusting the printing temperature to 20 °C and adding sodium bicarbonate resulted in a dough, which changed colour less, but still very distinctly. Bran pre-processing inactivated polyphenol oxidase activity by 77–92%, which stopped browning of the dough within 50 min without affecting the printing precision. The use of ultrasound, vacuum microwave and pulsed light could be extended to other food components to achieve a greater inactivation of undesirable enzymes. Pre-processing techniques resulted in minor differences in the baked snack, so their future choice depends mainly on the amount of water that can be added to the recipe.
The process of three-dimensional (3D) printing is of greatest interest to food science and engineering community because it offers numerous opportunities for innovative food design, new product ...formulations and personalized nutrition. Of particular interest are food inks based on cereal flours or starches, whose unique rheological properties make them suitable for 3D printing, typically with an extrusion-based printer. While the factors that influence the success of food printing are well addressed, the terminology and methods used to evaluate the process and product features are miscellaneous.
Therefore, this research work aims at providing an overview of the most commonly used parameters and methods for evaluation of the extrusion-based 3D printing process and the resulting cereal-based foods. Physical and sensory methods that are successfully used for the quality assessment of the ink and the printed raw objects, as well as the post-processed products are here reviewed and outlined. The properties of inks, usually determined with dynamic rheological tests, are linked to various aspects of printing quality whereas the physical properties of printed raw forms are usually evaluated by image analysis combined with mathematical calculations. Microscopy analysis is undertaken to study the microstructure of both the raw objects and the end-products, while texture analysis and sensory evaluation of final product are performed both by a panel and instrumentally. We provide details of the tests, but also emphasize the need to standardize the procedures and terminology in order to avoid misunderstandings and multiple variations of similar methods. This review provides a basis for further development and standardization of the methodology for quality assessment of 3D-printed cereal-based foods.
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•An overview of quality control procedures for 3D-printed cereal foods is presented.•Evidence linking dough rheology to printing quality is partly established.•The assessment of 3D-printed food quality requires improvement.•Methods and terminology for evaluating these products lack uniformity.
Gluten-free bread often has low nutritive value, high glycemic index (GI) and short shelf-life. The aim of this research was to investigate the influence of sourdough addition on GI, quality ...parameters and firming kinetics of gluten-free bread produced by partially baked frozen technology. Sourdough was fermented with a commercial starter of Lactobacillus fermentum and added to bread batter at four levels (7.5; 15; 22.5 or 30%). We determined biochemical characteristics of the sourdough and bread chemical composition, glycemic index in vivo, physical properties and firming kinetics after final rebaking. All breads were enriched with inulin and were high in fiber (>6 g/100 g). Control bread that was prepared without sourdough had medium GI (68). Sourdough addition decreased bread GI. However, only breads with 15 and 22.5% of sourdough had low GI. Moreover, addition of 15 and 22.5% of sourdough had positively affected the quality parameters of partially baked frozen bread: specific volume increased, crumb firmness decreased and firming was delayed. In conclusion, the combined application of sourdough and partially baked frozen technology can decrease glycemic index, improve quality and shelf-life of gluten-free bread. Such breads can be recommended as a part of well balanced gluten-free diet.
► We investigated sourdough addition to partially baked frozen gluten-free bread. ► Sourdough was added at four levels from 7.5 to 30%. ► We examined quality parameters, firming kinetics and glycemic index of breads. ► Bread with 15 and 22.5% sourdough had a low glycemic index, improved specific volume and crumb firmness, and delayed firming. ► Bread with 30% of sourdough had decreased shape and viscosity, and moderate glycemic index.
Food personalization and customization is now easier due to 3D printing, but the printing performance of gluten-free cereal material has hardly been explored. This research investigated the ...suitability of four gluten-free powder blends for snack 3D printing. The blends were analyzed for their powder properties, and a selected blend served as a model to optimize median particle size (20.9; 155.4; 255.9 μm), amount of water (90; 95; 100% blend basis), and nozzle diameter (0.84; 1.0; 1.2 mm). The best printing quality was achieved with a particle size of 20.9 μm, a water amount of 97.5% (blend basis) and a nozzle diameter of 0.84 mm. With optimized parameters, blends with similar chemical composition but different botanical origin were also printed successfully. However, the mixture with the highest viscosity (τ = 4580 Pa s) showed the best printing accuracy (88%). Powder analysis should be further investigated to be used as a predictor for printing quality.
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•Printing quality is strongly dependent on powder particle size and nozzle diameter.•Cryomilling of ingredients results in fine particles and high printing quality.•Higher batter viscosity contributes to higher printing accuracy.•Conditions defined for a model blend are applicable to others with similar composition.
Wheat bran has a short shelf life, which could be prolonged by reducing the activity of enzymes in lipid degradation. In this study, high-intensity ultrasound treatment (400 W, 80% amplitude, ...15 min), with or without cooling, was investigated for reducing the activity of lipase and peroxidase of wheat bran. Lipid stability parameters (free fatty acid content, peroxide value, anisidine value) of bran with coarse and reduced particle size (median 50th percentile diameter 503 and 177 μm, respectively) were followed under ambient or refrigerated storage conditions. Ultrasonic treatment without accompanying cooling inactivated 63% of lipase and 90% of peroxidase, but also decreased the antioxidant activity of bran by 13%. Compared with the untreated bran, the ultrasound-treated bran was darker, redder, and yellower. When ambiently stored, the critical anisidine value (10) of the unprocessed bran was exceeded after only 2 months, whereas the ultrasound-treated bran had an acceptable anisidine value for almost 12 months. Cooling during ultrasonication limits the ability to inactivate enzymes, and the reduction in bran particle size promotes its oxidative deterioration. The application of high-intensity ultrasound without cooling is beneficial for prolonging the oxidative stability of wheat bran compared to refrigerated storage.
•Ultrasound treatment reduces lipase and peroxidase activity of wheat bran.•Ultrasonic treatment prolongs bran stability from 2 to 12 months at ambient storage.•Ultrasound treated bran is more oxidatively stable than refrigerated bran.•Particle size reduction promotes oxidation of wheat bran.
Market reports show an increasing interest for healthy biscuits, with omega-3 and lignan rich flaxseeds being highlighted as key ingredients. Usage of milled flaxseed in comparison to the whole seed ...might improve bioaccessibility of lignans and omega-3, but also accelerate lipid oxidation, thus diminishing the consumers' acceptability.
This research investigated the nutritional (lignans, omega-3, phenolic acids, antioxidant activity), physical (texture, spreading), and sensory properties of biscuits made from whole wheat, rye, oat, and barley with added milled flaxseed (10% on flour basis), as well as oxidative stability during storage.
Lignans concentration in flaxseed biscuits (final range 101–117 mg/kg) was 30 times higher than in non-enriched whole-wheat biscuits (3.6 mg/kg), and concentration was unaffected by baking. The addition of flaxseed contributed to the variety of phenolic acids but not total phenolics, as well as increased the spread factor. The right combination of cereal flours with flaxseed resulted in sensory acceptance similar to white flour biscuits. While the barley-flaxseed combination was the least favourable, oat flour showed the best combination with flaxseed, but their acceptance significantly decreased during storage. Texture was dependent on the used cereal flour, as was the oxidative stability of biscuits which was minimally three months at ambient conditions.
•10% flaxseed biscuits have a substantial amount of lignans and omega-3 fatty acids.•Lignans are stable during the process of biscuit baking.•Combination of different cereal mixtures results in a sensory acceptable products.•Barley addition emphasizes the flaxseed aroma in biscuits.•Multi-cereal biscuits with flaxseed are promising diet improvement approach.
This study aimed to valorise the underutilised by-product of proso millet decortication. Millet bran was sieved into three fractions with substantially different nutritional profile. The fraction ...with diameter <500 μm had the highest nutrient density (14% protein, 26% starch, 36% dietary fibre, 9% fat, and 3 mg GAE/g phenolics (d.w.)) and was analysed for oxidative stability, micronisation effect under cryogenic or ambient conditions (2, 4, 8, 12 min), and baking applicability. The bran was oxidatively stable under refrigerator conditions for 150 days. Micronisation slightly increased the antioxidant activity measured by FRAP and ABTS assays as well as the content of fibre soluble in water and 78% ethanol as the bran particle size decreased from 171 μm to 26–46 μm. Gluten-free bread containing 10% of the nutrient-dense fraction of millet bran had higher dietary fibre (76%) and phenolics content (117%), improved volume and crumb softness, regardless of the bran particle size (diameter of 50th percentile 171 vs. 26 μm).
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•Nutrient-dense fraction can be separated from by-product of proso millet decortication.•The fraction <500 μm is a source of proteins, high in dietary fibre and phenolics.•Nutrient-dense fraction is stable in refrigerator for 150 days.•Micronisation has the potential to increase antioxidant activity and soluble fibre of proso bran.•Proso bran can be used for enrichment of gluten-free bread with fibre and phenolics.
Millet bran is a by-product rich in dietary fibre, micronutrients and bioactive compounds which are often deficient in a gluten-free diet. Previously, cryogenic grinding has been shown to improve the ...functionality of bran to some extent, although it offered limited benefits for bread making. This study aims to investigate the effects of adding proso millet bran depending on its particle size and xylanase pretreatment on the physicochemical, sensory and nutritional properties of gluten-free pan bread.
Coarse bran (
=223 μm) was ground to medium size (
=157 μm) using an ultracentrifugal mill or to superfine particles (
=8 μm) using a cryomill. Millet bran presoaked in water (for 16 h at 55 °C) with or without the addition of fungal xylanase (10 U/g) replaced 10% of the rice flour in the control bread. Bread specific volume, crumb texture, colour and viscosity were measured instrumentally. Along with proximate composition, the content of soluble and insoluble fibre, total phenolic compounds (TPC) and phenolic acids as well as total and bioaccessible minerals of bread were assessed. Sensory analysis of the bread samples included a descriptive, hedonic and ranking test.
Dietary fibre content (7.3-8.6 g/100 g) and TPC (42-57 mg/100 g) on dry mass basis of the bread loaves depended on bran particle size and xylanase pretreatment. The effect of xylanase pretreatment was most evident in the loaves with medium bran size in terms of higher content of fibre soluble in ethanol (45%) and free ferulic acid content (5%), improved bread volume (6%), crumb softness (16%) and elasticity (7%), but lower chewiness (15%) and viscosity (20-32%). Bread bitterness and dark colour were increased after adding medium-sized bran but its bitter aftertaste, crust crookedness, crumb hardness and graininess were reduced with xylanase pretreatment. Although bran addition impaired protein digestibility, it enriched the bread with iron (341%), magnesium (74%), copper (56%) and zinc (7.5%). Xylanase pretreatment of the bran resulted in the improved bioaccessibility of zinc and copper of the enriched bread compared to the control and bread without xylanase.
Application of xylanase to medium sized bran obtained by ultracentrifugal grinding was more successful than its application to superfine bran obtained by the multistage cryogrinding as it resulted in more soluble fibre in gluten-free bread. Moreover, xylanase was proven beneficial in maintaining desirable bread sensory properties and mineral bioaccessibility.
Legume flours can nutritionally enrich gluten-free bread but can also negatively affect its flavour. Although sourdough fermentation can improve bread flavour, its application to legume–cereal ...gluten-free matrices has been scarcely investigated. The aim of this study was to determine the effects of partial replacement (25%) of wholemeal rice with yellow pea flour (YPF) and the addition of sourdough (20%, dough basis) fermented with
Lactobacillus reuteri
DSM 20016,
Lactobacillus fermentum
DSM 20052 or
Lactobacillus brevis
DSM 20054 on the volatile profile and sensory properties of gluten-free bread. The 62 volatile compounds were quantified by HS-SPME/GC–MS. Quantitative descriptive and hedonic sensory analyses of bread odour and flavour were performed. The addition of YPF increased the concentration of undesirable hexanal,
(E,E)
-2,4-decadienal and benzaldehyde in bread. It also decreases the acceptability of crumb odour and bread flavour, mainly by increasing the intensity of the pea crumb odour, bread flavour and aftertaste. The addition of sourdough increased the concentration of desirable 2-methylbutanal, 3-methylbutanal, phenylacetaldehyde, octanal, nonanal and 3-methyl-1-butanol in bread, with the effect depending on the addition of YPF and the starter used for fermentation. It also decreased the concentration of undesirable hexanal and increased bread flavour and crumb odour acceptability of bread with YPF, mainly by decreasing the intensity of pea odour.
L. brevis
sourdough bread with YPF had the highest concentration of the above-mentioned desirable compounds.
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