Total Phenolic Content and Antioxidant Activity of Extruded Brown Rice

Health-promoting germinated rice and value-added foods: a comprehensive and systematic review of germination effects on brown rice

Over the last 30 years, thousands of articles have appeared examining the effects of soaking and germinating brown rice (BR). Variable germination conditions and methods have been employed to measure different health-beneficial parameters in a diverse germplasm of BR. Research results may therefore appear inconsistent with occasional anomalies, and it may be difficult to reach consensus concerning expected trends. Herein, we amassed a comprehensive review on germinated brown rice (GBR), attempting to codify 133 peer-reviewed articles regarding the effects on 164 chemical parameters related to health and nutrition in BR and in value-added food products. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA-2020) approach was used to direct the flow of the literature search. A pair-wise comparison t-test was performed to deliver an overall approach indicating when a given compound has been found to significantly increase or decrease through germination, which was grouped into GABA and polyamines, γ-Oryzanol and phytosterols, phenolic compounds, vitamins, proteins and amino acids, starchy carbohydrates, free sugars, lipids, minerals and phytic acid. This resource will stimulate interest in germinating rice and optimistically help increase both production and consumption of highly nutritious, health-beneficial rice with pigmented bran.

Sustainable production of naturally colored extruded breakfast cereals from blends of broken rice and vegetable flours

There is a growing demand for practical and healthy food products. Obtaining naturally colored breakfast cereals with the incorporation of functional ingredients is a promising alternative for consumers that are looking for healthiness. This study aimed to evaluate the feasibility of using vegetable flours, rich in pigments, to obtain naturally colored breakfast cereals through thermoplastic extrusion. Vegetables considered "unsuitable for the retail market", classified as "type B", were used to prepare different flours from carrot (CF), spinach (SF) and beetroot (BF). Extrudates were produced from a mixture of 90% broken rice (BR) and 10% vegetable flour (CF, SF or BF). Besides giving the extrudates a natural color, the use of vegetable flours also provided nutritional and functional enrichment due to increased mineral, protein, lipid, fiber and phenolic compound contents, and greater antioxidant capacity. However, some of these components, such as fibers, affect extrudate physical structure and technological characteristics, evidenced by reduced expansion, hardness, paste viscosity and greater interaction with water present in milk under consumption conditions. In general, the evaluated flours proved to be an alternative for imparting a natural color to extruded breakfast cereals, in addition to positively contributing to their nutritional and functional value.

Changes in physicochemical, nutritional characteristics and ATR-FTIR molecular interactions of cereal grains during germination

The cereal grains such as wheat, barley, sorghum, millets were evaluated before and after germination (24 h, 48 h and 72 h) and compared for their proximate composition, antioxidant activity, total phenolic content, total flavonoid content, pasting properties, in vitro starch digestibility and FTIR spectroscopy. Germination inversely affected the protein, fat, and ash content of different cereal grains. The germinated flours have less water content and higher oil absorption capacities along with reduced starch content. The contents of rapidly digestible starch (RDS), slowly digestible starch (SDS) and resistant starch (RS) in the ungerminated cereal flours ranged from 20.7 to 32.1%, 26.9 to 38.0% and 6.2 to 17.6% respectively but after germination of 72 h, the RDS content increased from 26.5 to 36.2% while SDS and RS content decreased from 26.1% (sorghum) to 16% (barley) and 14.7% (barley) to 4.6% (wheat) respectively. The drought-tolerant crops (sorghum, millets and barley) are potential sources of antioxidants and phenolic content and yielded lower hydrolysis index and estimated glycaemic index upon germination. The highest section of antiparallal β-sheet, α-helix and β-turns were found in wheat flour followed by sorghum flour and their proportion decreased with continuous germination. The continuous reduction of viscosity was evaluated with the progress in germination. Overall, germination is a way to get health-promoting compounds from less utilizing cereal such as millets, sorghum and barley and enhance their uses to nourish the huge population with the aim to fulfill their nutritional requirements.

Extrusion and nixtamalization conditions influence the magnitude of change in the nutrients and bioactive components of cereals and legumes

Cereal and legume diets make up the bulk of caloric sources for a majority of households in the developing world. They contain macro- and micronutrients as well as phytochemicals embedded as one matrix. Some phytochemicals are antinutritional factors which can bind nutrients thereby hindering their bioavailability. While there are other methods that can be used to enhance nutrient utilization from such foods, we summarize how food processing methods such as extrusion and nixtamalization are employed to break the food matrix and release these nutrients. Both extrusion and nixtamalization can break down complex carbohydrates into simpler, more soluble forms while at the same time inactivating or denaturing protein inhibitors and other antinutritional factors. Such disruptions of complexes within the food matrix are essential for harnessing optimum nutritional and health benefit from these foods. We present mechanistic approaches explaining how these processes enhance nutrient and mineral bioavailability and phytochemical bioactivity while minimizing the undesirable effects of antinutritional factors that coexist in the complex food matrix.

In vitro nutrient digestibility and antioxidative properties of flour prepared from sorghum germinated at different conditions

Germination can be used as a bio-processing practice to enhance the digestibility of nutrient and improve the bioactive compounds and rheological properties of food grains. In the present study, effect of germination time 12, 24, 36 and 48 h and temperature 25, 30 and 35 °C on carbohydrate profile, enzyme activity, in vitro nutrient digestibility, antioxidant activity, bioactive components and rheological characteristics of sorghum was examined. As time and temperature for germination progressed, it considerably enhance the activity of diastase enzyme and also the sugar content by hydrolysis of starch and further enhance the in vitro digestibility of starch by 10.50-36.25%. Germinated sorghum had high in vitro protein digestibility and it ranges from 57.50 to 77.91% as compared to native sorghum (54.09%). Germination of sorghum for longer time period at elevated conditions appreciably improve the antioxidant activity by 4.24-52.96%, total phenolic content and flavonoid content by 1.60-4.09 mgGAE/g and 60.30-94.03 mgQE/100 g, respectively Similarly reducing power increased from 29.27 to 47.19 µg AAE/g and metal chelating activity enhanced 19.48-52.09% as period for germination goes from 12 to 48 h and temperature from 25 to 35 °C. Increased enzyme activity during germination degrades the starch and thus lowers down the peak and final viscosity of sorghum. Increased enzymatic activity and higher antioxidant activity also lower down the lightness value by 12.48% while a* was increased by 6.78%. Germination of sorghum thus offers a tool to increase the nutrient digestibility and bioactive potential of sorghum without any chemical or genetic engineering.

Comparison among Activities and Isoflavonoids from Pueraria thunbergiana Aerial Parts and Root

Kudzu (Pueraria thunbergiana Benth.) has long been used as a food and medicine for many centuries. The root is the most commonly used portion of the plant, but the aerial parts are occasionally used as well. In this study, we investigated the constituent compounds and biological activities of the aerial parts, leaves, stems, and sprouts, and compared their constituents and activities with those of roots. Leaf extract showed a significantly higher TPC level at 59 ± 1.6 mg/g and lower free radical scavenging (FRS) values under 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid (ABTS), and NO inhibition at 437 ± 11, 121 ± 6.6 μg/mL and 107 ± 4.9 μg/mL, respectively, than those of sprout, stem, and root extract. Leaf extract also significantly suppressed lipopolysaccharide (LPS)-mediated gene expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). The main components of leaf extract were found to be genistin and daidzin. This study suggests that the leaves of kudzu are a good source of biological activities and isoflavones that can be used in functional or medicinal foods and cosmetics for the prevention or treatment of diseases related to inflammation and oxidative stress.

Effect of extrusion conditions on the physicochemical and phytochemical properties of red rice and passion fruit powder based extrudates

The passion fruit powder blended rice flour based extrudate was developed and investigated in terms of physicochemical and phytochemical properties. The extrusion process was performed using a twin screw extruder and optimized using rotatable central composite design followed by response surface methodology. The effect of process parameters such as temperature (80-150 °C), screw speed (200-400 rpm), moisture content (20-30%) and passion fruit powder (0-15%) on product quality was investigated. The optimum extrusion conditions of temperature, screw speed, feed moisture content, and passion fruit powder were 97.50 °C, 250 rpm, 25.20% and 11.25%, respectively. At optimum condition, the predicted values of responses were expansion ratio 8.05, water absorption index 2.77, total phenolic content 129.492 mg GAE/100 g and DPPH scavenging activity 65.79%. A comparison between optimized and control extrudates revealed that thermal, crystallinity and morphological properties of extrudates differed significantly. The comparison was also conducted in terms of FT-IR, SEM-EDS and HPLC analysis. The phytochemical properties showed that β-carotene, cyanidin-3-glucoside, peonidin-3-D-glucoside chloride were higher in control whereas the optimized sample evinced more (±)-α-tocopherol and D-α-tocopherol.

Bioactive components and functional properties of biologically activated cereal grains: A bibliographic review

Whole grains provide energy, nutrients, fibers, and bioactive compounds that may synergistically contribute to their protective effects. A wide range of these compounds is affected by germination. While some compounds, such as β-glucans are degraded, others, like antioxidants and total phenolics are increased by means of biological activation of grains. The water and oil absorption capacity as well as emulsion and foaming capacity of biologically activated grains are also improved. Application of biological activation of grains is of emerging interest, which may significantly enhance the nutritional, functional, and bioactive content of grains, as well as improve palatability of grain foods in a natural way. Therefore, biological activation of cereals can be a way to produce food grains enriched with health-promoting compounds and enhanced functional attributes.

Changes in functional properties and in vitro bioaccessibilities of β-carotene and lutein after extrusion processing

In this research, carrot pulp was added to traditional snack made from corn-grit. As the biological activity of carotenoids in the body depends on their bioaccessibility, change in carotenoid bioaccessibility during extrusion processing was investigated. In addition, phenolic content, antioxidant activity, β-carotene and lutein contents were investigated before and after the extrusion process. Two different temperature profiles were used for extrusion process. In-vitro bioaccessibilities of β-carotene and lutein increased by extrusion, β-carotene at both temperature profiles while lutein only at higher temperature profile. Extrusion decreased the antioxidant activity, total phenolic, β-carotene and lutein contents. Results suggest that even though amount of functional components decrease, in vitro bioaccessibility could be enhanced by extrusion. Therefore, carrot pulp can successfully be added as a functional ingredient to extrudated.

Factors influencing antioxidant compounds in rice

Epidemiological and clinical studies suggest that the additive/synergistic effects of several bioactive compounds are responsible for the health benefits of rice. Among the leading contenders are phenolic acids, flavonoids, anthocyanins, proanthocyanidins, tocotrienols, tocopherols, λ-oryzanol, and phytic acid, which all possess strong antioxidant activities in vitro. In this review, data related to health effects of rice antioxidants using cultured cells, rodents and humans models are first summarized. The evidence is strong that consumption of rice tocotrienols translates into improved health outcomes. Current research, however, does not strongly support the health-promoting effects of rice tocopherols and phenolic acids. The crucial limitations in studies using rice flavonoids, anthocyanins, proanthocyanidins, λ-oryzanol and phytic acid appear to be the appropriateness of the substance tested (i.e., purity), and the scarcity of animal and human interventions. In a second part, rice antioxidants are reviewed with an emphasis on their composition and contents. Taking into account the bioavailability of these compounds, it is evident that a number of factors affect the antioxidant composition of rice, making it difficult to estimate dietary intake. Before harvest, factors including soil type, atmospheric CO₂, chemical inputs, temperature, and degree of ripening are important. After harvest, rice is subjected to processing methods that include drying, parboiling, storage, irradiation, milling, stabilization, soaking, germination, fermentation, boiling, steaming, roasting, baking, and extrusion. Quantitative knowledge about the effects of these processes is summarized in this review. Surprisingly, a high level of agreement was found among study results, which could be useful in manipulating the growing and processing techniques of rice grains to facilitate efficient and safe consumption of antioxidant compounds.

Extrusion and Extruded Products: Changes in Quality Attributes as Affected by Extrusion Process Parameters: A Review

Extrusion of foods is an emerging technology for the food industries to process and market a large number of products of varying size, shape, texture, and taste. Extrusion cooking technology has led to production of wide variety of products like pasta, breakfast cereals, bread crumbs, biscuits, crackers, croutons, baby foods, snack foods, confectionery items, chewing gum, texturized vegetable protein (TVP), modified starch, pet foods, dried soups, dry beverage mixes etc. The functional properties of extruded foods plays an important role for their acceptability which include water absorption, water solubility, oil absorption indexes, expansion index, bulk density and viscosity of the dough. The aim of this review is to give the detailed outlines about the potential of extrusion technology in development of different types of products and the role of extrusion-operating conditions and their effect on product development resulting in quality changes i.e physical, chemical, and nutritional, experienced during the extrusion process.

The effect of extrusion on the functional components and in vitro lycopene bioaccessibility of tomato pulp added corn extrudates

The effect of processing on functional ingredients and theirin vitrobioaccessibility should be investigated to develop better food products.

Bound phenolics in foods, a review

Among phytochemicals, phenolic compounds have been extensively researched due to their diverse health benefits. Phenolic compounds occur mostly as soluble conjugates and insoluble forms, covalently bound to sugar moieties or cell wall structural components. Absorption mechanisms for bound phenolic compounds in the gastrointestinal tract greatly depend on the liberation of sugar moieties. Food processes such as fermentation, malting, thermoplastic extrusion or enzymatic, alkaline and acid hydrolyses occasionally assisted with microwave or ultrasound have potential to release phenolics associated to cell walls. Different kinds of wet chemistry methodologies to release and detect bound phenolic have been developed. These include harsh heat treatments, chemical modifications or biocatalysis. New protocols for processing and determining phenolics in food matrices must be devised in order to release bound phenolics and for quality control in the growing functional food industry.