Potential of Pigmented Rice in Bread, Bakery Products, and Snacks: A Narrative Review of Current Technological and Nutritional Developments

Heavy metal is a serious abiotic factor that affects the growth and production of rice. In view of important properties such as anti-oxidant, anti-diabetic, anti-cancer activities and anti-cancer activities of pigmented rice, two important local pigmented rice varieties - Chakhou (Manipur) and Kawnglawng (Mizoram) were selected for this study. This study was conducted during the month of March to October (2018 to 2020) at the Department of Botany, Mizoram University, Mizoram, India to investigate the effects of zinc stress on two pigmented and aromatic local rice cultivars Chakhou and Kawnglawng. The pigmented rice cultivars were analyzed for germination percentage, protein contents, chlorophyll a and chlorophyll b, antioxidant enzymes- catalase (CAT) and ascorbate peroxidase (APX) and genome template stability (GTS) under different zinc stress conditions. Zinc stress affected chlorophyll and protein contents while CAT and APX activities were increased significantly. PCR-based Random Amplified Polymorphic DNA (RAPD) technique was employed to investigate the genome stability of the rice cultivars against zinc stress. Genome template stability (GTS) was found to be high (>94%) in both the cultivars. Hence, these cultivars can be suggested as a source for future breeding programs against zinc stress.

Pigmented rice is a good source of nutraceuticals because it contains antioxidants such as anthocyanins, flavonoid and other phenolic compound as well as essential minerals. On an average, the three mineral contents in rice genotypes followed an order of Zn > Fe > Cu. The anthocyanin content among 22 pigmented genotypes ranged from 1.56 to 7.56 mg cyanidine 3-O-glucoside per 100 g. The DPPH activity was highest in the pigmented glutinous rice cultivar Kmj Bora-50 (21.73 %) and lowest in Til Bora-2 (14.54 %). Total phenolic acid content was highest in the pigmented glutinous rice cultivar Kmj Bora-50 (80.16 mg GAE per 100 g) and lowest in Ronga Bora-6 (53.47 mg GAE per 100 g). The Flavonoid content was highest in the pigmented glutinous rice cultivar Kmj Bora-50 (60.76 mg QE per 100 g) and lowest in Ronga Bora-6 (45.57 mg QE per 100 g). A significant correlation was observed among different parameters studied. The amount of phytochemicals present in the fresh samples decreased after cooking.

Effects of cooking on phytochemical and antioxidant properties of pigmented and non-pigmented rare Indian rice landraces

Roasting has been suggested to enhance the nutritional quality of many foods. The present work determined how roasting temperature (100, 150, and 200°C) and duration (10 and 20 min) affect anthocyanin, total phenolic contents, and antioxidant capacity in pigmented and non-pigmented rice. The concentration of anthocyanin in pigmented rice increased by 15% when roasted at 100°C for 20 min, but it dramatically decreased at higher temperature for longer time. The anthocyanin analysis profile showed that cyanidin-3-glucoside and peonidin-3-glucoside were found as the major compounds of pigmented rice, in which the first compound was about 14 folds higher than the latter, in both non-roasted and roasted rice. The concentration of cyanidin-3-glucoside slightly increased in the roasting rice but not for peonidin-3-glucoside. The total phenol concentration and antioxidant capacity in pigmented rice were not affected by the roasting treatments. In non-pigmented rice, total phenol concentrations and DPPH activity increased with increasing roasting temperature and duration. There were significant correlations between anthocyanin and total phenol concentrations in pigmented rice, and between total phenol concentration and antioxidant capacity determined by DPPH activity in non-pigmented rice. The optimum roasting temperature and time for maximising anthocyanin and total phenol was 100°C for 20 min for pigmented rice, and 200°C for 20 min for non-pigmented rice, as these treatments yielded the highest total phenol concentration and DPPH activity. The present work reveals that anthocyanin and total phenol concentrations of rice grains can be changed by roasting, but the direction and magnitude of the changes depend on the temperature and duration of the treatment as well as the rice variety.

Abstract. Hamidah, Sunaryo W, Rusdiansyah, Nurhasanah. 2024. Genetic diversity and cluster analysis of local pigmented rice from East and North Kalimantan, Indonesia based on quantitative and qualitative characters. Biodiversitas 25: 1938-1945. Pigmented rice is a functional food containing antioxidants and various essential nutrients that are very beneficial for health. The substantial advantages of pigmented rice encourage the importance of research activities in exploring pigmented rice germplasms and further identifying unique and valuable traits for the development of superior rice varieties. This research aims to evaluate genetic diversity of pigmented rice based on quantitative and qualitative characters and examine their genetic relationship for future pigmented rice improvement strategies. Fifteen pigmented rice from East and North Kalimantan, Indonesia were used in this study. Nine quantitative and ten qualitative traits were observed and used to identify the genetic diversity of pigmented rice cultivars. The data then were used to group the pigmented rice based on their similarity degree using cluster analysis to form a phylogenetic tree hierarchically in a dendrogram. The results showed that there were large genetic differences based on quantitative and qualitative characters in the pigmented rice, showing a high genetic diversity either in brown or black rice cultivars. Based on the genetic relationships analysis, the fifteen pigmented rice cultivars were clustered in four groups with genetic similarity of ?90%. The genetic diversity and relationship in this study emphasize the crucial of revealing the genetic identity of local pigmented rice from East and North Kalimantan.

A comparative study of dietary fiber content, In vitro starch digestibility and cooking quality characteristics of pigmented and non–pigmented traditional and improved rice (Oryza sativa L.)

Antioxidants help to mitigate oxidative stress, prevent non-communicable diseases, and promote health. Rice (Oryza sativa L), a staple food, contains antioxidants and comes in various varieties locally. This study assessed the antioxidant capacity of pigmented and non-pigmented rice varieties grown in Sri Lanka, focusing on the relationship between pericarp colour strength and antioxidant levels before and after milling and cooking. Forty rice varieties, including improved, traditional, and exotic types, were cultivated, harvested, processed, and sampled concurrently. The DPPH assay was used to assess the free radical scavenging capacity of rice at three processing stages: whole, milled, and cooked. The effective concentration (EC₅₀), defined as the concentration required to scavenge 50% of DPPH radicals, was calculated. The reciprocal of EC₅₀ was expressed as the antiradical power (ARP). Additionally, the total antioxidant capacity was measured using Ferric Reducing Antioxidant Power (FRAP) assay. Colour values for lightness, redness, and yellowness of whole, milled, and cooked rice were recorded with a CR-20 colorimeter. Both methods revealed significantly higher antioxidant capacity in pigmented whole rice (p ≤ 0.05), with traditional varieties such as Masuran and Nonabokra and improved varieties such as Ld 368 and Ld 408 demonstrating promising antioxidant levels. A significant decline in antioxidants was observed after milling and cooking (p ≤ 0.05), with a greater loss occurring from whole to milled rice than from milled to cooked rice. Cooked pigmented rice had six times more antioxidants than non-pigmented rice. Milling resulted in a substantial reduction in both antioxidant capacity and redness, while cooking caused a comparatively smaller loss (p ≤ 0.05). Overall, antioxidant activity was reduced by up to 96% as a result of milling and cooking. Although processing reduces redness and increases lightness in pigmented rice varieties, a deeper red colour does not necessarily indicate higher antioxidant levels. Positive correlations between antioxidant capacity and pericarp colour values suggest that lighter reddish-yellow rice had significantly greater antioxidant capacities.

Ever since the flavonoids and other antioxidants in rice were demonstrated with immense health benefits, much interest has been diverted to study the native indigenous rice landraces. In the present investigation, three pigmented rare Indian rice landraces and two non-pigmented rice varieties were analyzed for their phytoconstituents like total phenolic content(TPC), total flavonoid content(TFC), total anthocyanin content and antioxidant potential using 1,1-diphenyl-2-picrylhydrazyl (DPPH)radical scavenging activity. The phytochemical profile was compared between seed, seedling, stem, leaf and root tissues of the different varieties. Pigmented rice cultivars demonstrated higher levels of bioactive compounds as compared to the non-pigmented cultivars exhibiting a strong correlation between the antioxidant activity of the grain and their phenolic and flavonoid content. Among the fivedifferent rice studied, black navara was found to be superior in terms of its phytochemical composition. Further, the expression levels of flavonoid genes among pigmented and non-pigmented rice was studied. Higher gene expression profiles were observed in the 8 flavonoid genes studied in pigmented rice varieties as compared to non-pigmented varieties. The colorlessness of non-pigmented rice and its lower levels of phytoconstituents correlated with the low transcript levels of flavonoid genes recorded in them. This study provides a basis for understanding the health-promoting properties of pigmented rice over non-pigmented rice at the biochemical and molecular levels.

Pigmented rice has attracted major attention because of its higher levels of bioactive compounds and its higher concentration of micro- and macronutrients, compared with white rice. Pigmented rice cultivars are found in various colors i.e. black, purple, red, and brown. Pigmented rice contains good amounts of vitamins, minerals, fiber, and different phytochemicals with beneficial health effects. Pigmented rice is abundant in phenols, flavonoids, and antioxidant compounds. In comparison with white rice varieties, colored rice contains higher levels of polyphenols. Starch is the main component of rice grain, and it accounts for about 72–82% of brown rice and 90% of milled rice. Native starches have many drawbacks; to improve these properties, starch is generally modified using different physical, chemical, and enzymatic treatments. Functional properties are the basic physicochemical properties of flours, which have a complex relationship between different components of grains. Pigmented rice has desirable functional properties, which are essential for product formulations. Pigmented rice has been reported to have several health benefits including preventing hypertension, gluten-related disorders, and heart diseases; as well as having anti-diabetic potential, antioxidant properties, anti-inflammatory activity, and anti-cancer activity. This chapter will highlight the opportunities for developing novel health supplements from pigmented rice flours. Biotechnology is used in various crops, including rice, to improve its desirable properties. In this chapter, we will provide an overview of the nutritional composition, bioactive characteristics, functional properties and health benefits of pigmented rice.

The Aim / Objective: Using eggplant puree to reduce fats and egg in bakery products to reduce calorie and increase nutritional value of cake (muffins) also, technological and sensory evaluation of muffin produced. Maximizing the use of eggplant from an economic point of view, as it is a cheap and available product in the Egyptian market, maximizing the health benefits of eggplant by producing a product with high nutritional value and low in fat, take advantage of dietary fiber in vegetables, producing a new product with high nutritional and biological value, take advantage of various antioxidants from their natural sources, improving the quality characteristics of products (sensory qualities), especially color and using natural vegetables as fat substitutes in bakery products.
 Study Design: Analytical study.
 Place and Duration of Study: Department of Bread & Pastries, Food Technology Research Institute, between June 2020 and August 2022. Methodology: We prepared the muffins blend and formulas and did all analysis (chemical – physical – sensory evaluation – texture… for muffins resulted.
 Results: Eggplant puree (EP) (25, 50, 75 and 100%) was used to replace fat and egg in the muffins production. Muffins prepared with 25% (EP) had a higher volume than control Muffins. Muffins volume was alikeness between control muffins and the sample used 50% (EP). At 100% replacement level, the muffins volume is minimal. Low-fat and egg muffins with (EP) had higher moisture and minerals also less calories than control. Replacing baking butter by (EP) gave a significant rising in springiness hardness, and chewiness, and a limited result of cohesiveness. But, there were no inequality between control muffins and the acceptance of low (fat and egg) muffins up to 75%. Adding (EP) did not result in undesirable variations in color. Likewise high moisture content in (EP) muffins was acceptable by the panelists. Results clarified that (EP) is an acceptable fat alternative in muffins and efficient in reducing the amount of fat and calories, likewise (EP) could be used as egg replacer in muffins and cakes. Furthermore, during storage moisture loss and increase of muffins hardness was observed in produced muffins. Result showed great acceptance for produced muffins.
 Conclusion: This work is an attempt to raise the economic value of eggplant by using it in some bakery products that may not affect its technological properties while reducing the energy percentage and the price of the product. By studying all the technological, sensory and chemical properties, it was found that fat can be replaced by 100% with eggplant puree, and the ability to replace eggs by 25%, as these samples gave a result similar to the control in all the properties of the tests, while the increase in the percentage of replacing eggs with eggplant puree to 50 and 75% led to a decrease In the technological properties, however, it was accepted by a large percentage up to 75 and 85% of the various laboratory tests, and therefore it is acceptable according to the taste of the consumer and from the view point of the producer.

The total phenolic compounds and flavonoid contents of grains as well as the antioxidant capacities were determined in 15 rice varieties. A high-performance liquid chromatography method was modified for the determination of the flavonoid subgroups in rice grains. The results showed the total phenolic compounds, flavonoid contents, and antioxidant capacities of pigmented rice were higher than in non-pigmented rice. The amounts of flavanone groups ranging from 0.04 to 0.40 mg Naringenin g−1, while flavones groups ranging from 0.08 to 0.57 mg Apigenin g−1, flavonol groups ranging from 0.16 to 1.20 mg Quercetin g−1 and anthocyanin groups ranging from 44.43 to 69.83 mg Cyanidin chloride g−1 were found in pigmented rice. The total phenolic compounds and total flavonoid contents of grains were significantly correlated with their antioxidant capacities. The results indicated that pigmented rice appeared as a good source of phenolic and flavonoid compounds and had beneficial nutritive values or antioxidant substances.

Characterizing the pigmented traditional rice cultivars grown in temperate regions of Kashmir (India) for free and bound phenolics compounds and in vitro antioxidant properties

Pigmented rice bran is under-researched for human nutrition. This study investigated milling and cooking effects on the physicochemical and nutritional quality of pigmented and non-pigmented rice. Raw rice properties, cooking behavior and nutritional in-vitro quality were evaluated. Samples were cooked following a “risotto” preparation method. Bran removal by milling reduced kernel dimension (15%) and hardness (8%). Pigmented rice had higher total phenolic content (TPC; >41%) and higher antioxidant activity (AOA; >24%) than Carnaroli but milling significantly (p ≤ 0.05) reduced them. The bran was fractionated and (re)added during rice cooking as a new strategy to preserve nutritional compounds at their best. Compared with brown rice, milled samples exhibited greater geometric expansion and shorter cooking times (>47%), confirming that removal of the outer layer facilitated water penetration. Cooking affected the TPC differently depending on the rice variety (e.g., -15.5% for Violet and +7.8% for Orange brown samples). The incorporation of rice bran during cooking improved the “risotto” color and its nutritional value (TPC > 53% and AOA > 60%). Results evidenced the impact of different processing methods on rice quality, suggesting the potential use of rice co-product (i.e., bran) as new ingredient for healthier and more sustainable foods.

Comparative analysis of rice reveals insights into the mechanism of colored rice via widely targeted metabolomics

Production of high quality pigmented rice contained with high content of anthocyanin, and polyphenol was significantly influenced by cultivation environments like transplanting date and cultivation location. This study was carried out to establish an optimum transplanting date and cultivation region to produce maximum content of anthocyanin, polyphenol and antioxidant activity of pigmented rice varieties (black, red colored). Three transplanting times (May 20, June 5, June 20) and four different sites (Miryang, Uiseong, Sangju, Bonghwa) were evaluated with five pigmented rice cultivars. Anthocyanin and total polyphenol index to average temperature during 30 days after heading (DAH) of black, red pigmented rice varieties showed that anthocyanin and total polyphenol contents were decreased by 10% and 9%, respectively, with increasing average temperature of . The optimum ripening temperature of the 30 DAH for the production of high anthocyanin and total polyphenol was 22 to for early maturity black rice, 21 to for mid-late maturity of black and red rices, respectively. On the other hand, an estimated heading date of pigmented rices in return according to the optimum ripening temperature of the 30 DAH was ranged Aug. 11 to 17 for early maturity black rice, Aug. 25 for mid-late maturity black, red rice variety in Jecheon, Aug. 27 to Sep. 2 for early maturity type, Sep. 3 to 6 for mid-late type in Daegu. It seemed that Jecheon, Boeun, Mungyeong, and Yeongju were optimum regions for cultivation of pigmented rices. The estimated sowing date of pigmented rices for high anthocyanin and total polyphenol production based on the optimum heading date was May 18 to 26 for early maturity black rice variety, April 11 for mid-late black, red variety in Jecheon, May 23 to 28 for early type, April 9 to 26 for mid-late type in Boeun, respectively.