Recipient Organization
UNIVERSITY OF MISSOURI
(N/A)
COLUMBIA,MO 65211
Performing Department
Food Systems & Bioengineering
Non Technical Summary
Purple corn, a colored variant of corn, is a rich source of chemical compounds known as polyphenols. On account of their anti-oxidant, anti-inflammatory, anti-diabetic and anti-carcinogenic properties, the ingestion of polyphenols is associated with many health benefits in humans. Anthocyanins, belonging to a class of polyphenolic compounds, are natural pigments responsible for red, purple, blue and black colors in fruits and vegetables such as blueberries, black grapes etc. On account of its very high anthocyanin content (four times as much as blueberries), purple corn can be used as an economically viable source of natural red color for food industry. Currently, food industry utilizes synthetic food colorants derived from petroleum which is a cause of concern for many consumers. However, anthocyanin-based natural color from fruits and vegetables remains expensive, and as a result not many food products containing natural red color are available in the market. During the PD's doctoral research work, the potential of using purple corn as an economical source of natural red color for the food industry was explored and it was found to be a viable alternate. Furthermore, a polyphenol-rich water extract from purple corn was found to be detrimental to the growth of insects implying its potential use as an eco-friendly alternate to potentially harmful chemical pesticides in high value crops such as organic fruits and vegetables. This proposal lays the framework of further research with a significant potential of benefitting a number of sectors including natural food color industry, eco-friendly pest management, food supplement and corn fractionation industry as well as the farmers and consumers.
Animal Health Component
80%
Research Effort Categories
Basic
20%
Applied
80%
Developmental
(N/A)
Goals / Objectives
This research work will be broadly divided into two distinct parts spanning seven different objectives. The first part of research covering objectives 1, 2, 3 and 4 will be conducted in PD's corn processing and food engineering lab and will mainly concentrate on the preparation and evaluation of corn-based color extract, and validation of its applications in different food matrices. The second part of the research work covering objectives 5, 6, and 7 will include extensive multidisciplinary collaboration with experts from within and outside the University of Missouri.During dry milling of purple corn, it was observed that corn pericarp broke down into small fractions and almost 50% of it was distributed in coproducts other than pericarp (Li et al., 2017; Somavat et al., 2016). Therefore, optimization of dry milling parameters can result in increased recovery of corn pericarp, thereby increasing the overall process efficiency. It will also be of interest to identify different solvent combinations and evaluating novel extraction processes such microwave assisted extraction and membrane separation etc. for increased anthocyanin and polyphenolic compound recovery from the pericarp. The suitability and economics of spray and freeze-drying processes need to be evaluated for the preparation of dried color extract, following which it can be incorporated into different food matrices and subsequently processed to identify the effects of different processing methods and parameters on the degradation kinetics of anthocyanins and other phenolics. The shelf stability of anthocyanins-based color in different food material during storage will have a final bearing on their eventual acceptance by the industry. This work has a strong potential to solve a significant food industry problem and will also be helpful to corn producers as they will be able to supplement their income by diversifying into pigmented corn production. The specific goals of the proposed study are divided into seven objectives:Optimization of anthocyanin recovery from purple corn.Formulation of shelf stable anthocyanin-based color extract from purple corn.Studying the effects of different processing operations on degradation of anthocyanins and phenolic compounds in various food material,Determination of color stability of anthocyanin extract in different food matrices during various storage conditions.Development of a purple corn cultivar suitable for the Midwest in collaboration with plant scientists.Research into antimicrobial properties of polyphenol-rich purple corn extract.Research into insect/pest deterrent properties of purple corn extract as an alternate to synthetic pesticides.
Project Methods
The first and second objectives will deal with optimizing the pericarp recovery from purple corn and efficient formulation of a usable color extract from recovered pericarp. Additional work is required in establishing optimal corn dry milling parameters such as corn moisture content, kernel tempering time and post-degermination conditioning time for increased pericarp recovery. Lab scale 1 kg dry milling procedure developed by Rausch et al. (2009) will be used for this work. Anthocyanins will be extracted from separated pericarp using various solvent combinations with an aim of extracting the maximum amount of phenolic compounds. Novel extraction methodologies such as microwave assisted extraction and membrane separation will be evaluated. Finally, powdered color extract will be prepared by spray and freeze-drying methods and analyzed for their respective compositional characteristics. Fernandez et al. (2014) studied the anti-oxidant activity of spray dried extracts of Psidium gujava leaves using different drying carriers such as maltodextrin, gum arabic etc. and found significant anti-oxidant activities in spray dried extracts. In another work, the stability of a spray dried extract of medicinal plant Bidens pilosa L. was studied for 12 months at different storage conditions and it was reported that two polyphenols, namely, rutin and hyperoside demonstrated lower degradation (Cortes-Rojas et al., 2016). Blackberry extract was prepared using a spray dryer with mannitol as a thermoprotectant and it was reported that mannitol prevented thermal deterioration of polyphenolic species such as anthocyanins and polyphenols during spray drying (Eldridge et al., 2014). Freeze dried wild blueberry extract was also reported to undergo anthocyanin deterioration, however, this was minimum at 25 °C storage temperature (Fracassetti et al., 2013). This research work will help in developing optimal milling and drying parameters for the preparation of a usable color extract from pigmented corn and help identify suitable protectants/encapsulation material for preventing anthocyanin and polyphenolic degradation during spray and/or freeze-drying operations.In the third objective of the proposed research, prepared color extract will be incorporated in various food matrices. These food materials will undergo different processing operations such as extrusion, baking, HTST and UHT, and the effects of these operations on anthocyanin degradation kinetics in different food matrices will be studied. Shoji (2007) reported that during food processing, anthocyanins may react with flavonols and proanthocyanidins, resulting in color degradation. In another work, Patras et al. (2010) reported a general degradation of anthocyanins at higher temperatures, however, they reported that only a limited information was available on the thermal degradation of anthocyanins during food processing. Furthermore, it also needs to be understood whether other compounds formed due to polyphenolic degradation also possess anti-oxidant activities in food material. Sui et al. (2015) incorporated anthocyanin rich black rice powder in bread dough and studied the anthocyanin degradation kinetics during baking. They reported higher anthocyanin degradation at 125 °C compared to 65 °C and found greater decrease in antioxidant capacity and total phenolic content in bread crumb compared to the bread crust. This work will help better understand anthocyanin and polyphenol degradation kinetics during different food processing operations and identify ideal processing parameters which will ensure maximum retention of anthocyanins in processed food products. The fourth objective will involve incorporation of various concentrations of prepared color extract into different food and beverage matrices and studying their color stabilities under different storage conditions over time. In a study by Muche et al. (2018), juices from Merlot and Ruby grapes were stored for a year and analyzed for anthocyanin degradation and change in color. It was found that anthocyanin degradation followed a first order reaction kinetics and this degradation was higher at 25 °C and 35 °C compared to 5 °C. Hellstroem et al. (2013) studied the stability of anthocyanins in berry juices stored at different temperatures and reported that this degradation was higher at room temperature compared to the cold storage. They also reported that only 11-15% of the original anthocyanin content was detected in two commercial juices after the expiry date. In another work, the effect of light on anthocyanin stability in ethanolic blackberry extract was studied. It was reported that the anthocyanin degradation followed a second order reaction kinetics and the t1/2 at high illuminance of 3968.30 lux was 28.20 hr (Contreras-Lopez et al., 2014). In addition, we also plan to study anthocyanin stabilities in food materials with different pH levels. These food samples will be stored for 3-6 months under different temperature and light exposure conditions and the effects of various parameters on final product color during the storage period will be determined.The objectives 5, 6 and 7 will be studied in collaboration with experts from within and outside the University of Missouri. The potential of working with breeders on development of a purple corn variety suitable for Midwestern US will be explored. Such a variety will not only help in reducing the dependence of Midwestern farmers on yellow dent corn, it will also have a potential of benefitting many different sectors of agricultural industry as discussed earlier. Since we know that many of the secondary metabolites are synthesized in plants as a defense mechanism against predators. The polyphenol-rich extract from purple corn pericarp, on account of its high anthocyanin, tannins and flavonoid content can be potentially utilized as an anti-microbial agent in different food and beverages as well as an eco-friendly pest deterrent in high value organic crops. Anti-microbial properties of extracts from grapefruit seed (Cvetnic & Vladimir-Knezevic, 2004), green tea extract (Hong et al., 2009; Kim et al., 2004) and grape extract (Ahn et al., 2007) have been already been documented. On account of its higher content of polyphenolic compounds, the aqueous extract from purple corn pericarp will be tested for its anti-microbial properties against a number of foodborne pathogens in different mediums. The final objective will involve continuation of testing of polyphenol-rich purple corn pericarp extract as an eco-friendly pest deterrent. We have already documented the efficacy of this extract against tobacco hornworm caterpillars (Tayal et al., 2020a; Tayal et al., 2020b) and further work will include crop-specific pests. This work will be conducted in collaboration with internal and external collaborators. To sum up, these studies will demonstrate the potential of purple corn anthocyanin extract as an economically viable alternate to FD&C Red 40 dye and highlight its numerous applications in a number of different agriculture-based industries. Furthermore, this work will expand existing scientific knowledge in a number of sectors including but not limited to natural food colors, eco-friendly pest management, plant-based antimicrobial agents and entails a significant potential of benefiting the farmers, industry and consumers alike.