Carotenoid and color changes in traditionally flaked and extruded products

A Review of the Changes Produced by Extrusion Cooking on the Bioactive Compounds from Vegetal Sources

The demand for healthy ready-to-eat foods like snacks is increasing. Physical modification of vegetal food matrices through extrusion generates significant changes in the chemical composition of the final product. There is a great variety of food matrices that can be used in extrusion, most of them being based on cereals, legumes, fruits, vegetables, or seeds. The aim of this review was to summarize the main effects of the extrusion process on the bioactive compounds content, namely phenolics, terpenes, vitamins, minerals, and fibers of vegetal mixes, as well as on their biological activity. The literature reported contradictory results regarding the changes in bioactive compounds after extrusion, mainly due to the differences in the processing conditions, chemical composition, physicochemical properties, and nutritional value of the extruded material and quantification methods. The thermolabile phenolics and vitamins were negatively affected by extrusion, while the fiber content was proved to be enhanced. Further research is needed regarding the interactions between bioactive components during extrusion, as well as a more detailed analysis of the impact of extrusion on the terpenes since there are few papers dealing with this aspect.

Influence of Air-Drying Conditions on Quality, Bioactive Composition and Sensorial Attributes of Sweet Potato Chips

The drying process is an essential thermal process for preserving vegetables and can be used in developing dried products as healthy alternative snacks. The effects of air-drying conditions using a convection dryer with hot air at different temperatures (60°, 65°, 70°, 75°, and 80 °C, in the range 5–200 min, at a fixed air speed of 2.3 m/s) were tested on the quality of slices (2.0 ± 0.1 mm) of dried sweet potato (Bellevue PBR). For each time and temperature, drying condition, physicochemical parameters (moisture content, CIELab color, texture parameters, total phenolic and carotenoid contents) and a sensory evaluation by a panel at the last drying period (200 min) were assessed. Drying time was shown to have a more significant effect than temperature on the quality of dried sweet potato as a snack, except for carotenoid content. Given the raw tuber content, thermal degradation (p < 0.05) of total phenolic compounds (about 70%), regardless of tested conditions, contrasted with the higher stability of total carotenoids (<30%). The dried product, under optimal conditions (≥75 °C for 200 min), achieved a moisture content (≤10%) suitable for preservation, providing a crispy texture with favourable sensory acceptance and providing a carotenoid content similar to the raw product.

Andean purple maize to produce extruded breakfast cereals: impact on techno-functional properties and sensory acceptance

BACKGROUND

Andean purple maize (APM) is an ancient crop widely used as a natural coloring in traditional Peruvian cuisine. However, it has been little explored within the food industry. The present study assessed how APM impacts on techno-functional properties and sensory acceptance of breakfast cereals. Extruded samples formulated with 100, 75, 50, and 25% APM, and complemented with yellow corn grits (YCG), were analyzed for their techno-functional and sensory properties.

RESULTS

Increases in bulk density, as well as reduction in the expantion and porosity were observated for extrudates containing ≥ 50% APM, accompanied by an increase in purple color intensity. Increase in milk absorption index, reduction in milk solubility index and decrease in cereal hardness with increase in APM were also observed. Despite this, APM extented the cereal bowl-life. High sensory scores of overall liking (6) and color (7) were obtained for extruded formulations containing ≥ 50% APM and low values for extrudates with 25% APM. Aroma, flavor, and texture scores did not present significant differences.

CONCLUSION

APM is an ingredient with the potential to be used to produce breakfast cereals since it improves their techno-functional characteristics and sensory acceptance, at the same time, it leads to the production of healthy, nutritious, and sustainable food. © 2022 Society of Chemical Industry.

Quinoa Snack Production at an Industrial Level: Effect of Extrusion and Baking on Digestibility, Bioactive, Rheological, and Physical Properties

This research aimed to produce gluten-free snacks on a pilot scale from quinoa flour. These snacks experienced an extrusion process, followed by baking. The effects of these technological processes on carbohydrate and protein digestibility, extractable phenolic compounds (EPP), hydrolyzable phenolic compounds (HPP), antioxidant capacity, and physical properties were evaluated in raw quinoa flour and extruded snacks. Extrusion increased digestible starch (RDS) from 7.33 g/100 g bs to 77.33 g /100 g bs. Resistant starch (RS) showed a variation of 2 g/100 g bs. It is noteworthy that protein digestibility increased up to 94.58 g/100 bs after extrusion and baking. These processes increased HPP content, while EPP and carotenoid content decreased. The samples showed significant differences (p < 0.05) in the antioxidant properties determined through the DPPH and ABTS methods. Values of 19.72 ± 0.81 µmol T/g were observed in snacks and 13.16 ± 0.2 µmol T/g in raw flour, but a reduction of up to 16.10 ± 0.68 µmol T/g was observed during baking. The baking process reduced the work of crispness (Wcr) from 0.79 to 0.23 N.mm, while the saturation (C*) was higher in baked ones, showing higher color intensity. The baking process did not influence the viscosity profile. The results in this study respond to the growing interest of the food industry to satisfy consumer demand for new, healthy, and expanded gluten-free snacks with bioactive compounds.

Correlation analysis between extrusion process variables and quality of purslane leaf powder rice extrudates

Extrusion has become one of the most popular techniques in food processing, and the process parameters are closely related to product quality. Purslane (Portulaca oleracea L.) can be used in medical and food products as a vegetable and herb. It has limited application in extrusion. The effects of extrusion process variables (screw speed, barrel temperature, and feed moisture) on system variables (specific mechanical energy [SME], die head pressure, and torque) and target variables (water absorption index, water solubility index, iodine blue value, color, pasting properties, and textural properties) of purslane powder compound rice were studied. The results showed that SME was moderately positively correlated with screw speed (r = 0.608, p < 0.05). However, torque was moderately negatively correlated with feed moisture (r = -0.574, p < 0.05), and die head pressure was moderately negatively correlated with barrel temperature (r = -0.635, p < 0.01). The target variables of extrudates were also correlated with the system parameters to varying degrees. These results are helpful to control and predict the texture, pasting properties, and other quality characteristics of extruded products containing purslane powder. PRACTICAL APPLICATION: The results showed that torque and die head pressure were moderately negatively related to barrel temperature, specific mechanical energy was moderately positively related to screw speed, peak viscosity and breakdown viscosity were moderately negatively related to specific mechanical energy, and water absorption index was moderately negatively related to torque and die head pressure. It provides a reference for the research of influencing system parameters and changing product quality by controlling extrusion process parameters. In this study, some possibilities for the application of broken rice and purslane in extrusion processing were proposed.

In Vitro Bioaccessibility of Bioactive Compounds from Rosehip-Enriched Corn Extrudates

The rosehip (Rosa canina L.) fruit has gained researchers′ attention due to its rich chemical composition in vitamin C, phenols, carotenoids, and high antioxidant activity; meanwhile, polymers such as pea protein are generally recognized as exhibiting a protection role against the extrusion process. Corn snacks extrudates obtained by replacing corn flour with 10% R. canina powder (R) and 10% R. canina with pea protein (RPP) were evaluated for the physicochemical, textural, optical, and nutritional characteristics. A sample manufactured without R. canina powder was used as a control. Hardness, crispiness, chewiness, and solubility index (WSI) of the final extrudates were improved by addition of R. canina and pea protein powder (PP); meanwhile, b* (yellow/blue coordinate), C (chroma), and h* (tone) optical parameters were significantly different from the control sample (p < 0.05). Extrusion highlighted a negative impact on total phenols, carotenoids, vitamin C, and antioxidant activity extrudates, while PP exhibited a good protection against the extrusion process. In vitro digestion increased the bioaccessibility of vitamin C, folate, antioxidant activity, total phenols, and total carotenoids mainly on RPP extrudates.

A review of extrusion-modified underutilized cereal flour: chemical composition, functionality, and its modulation on starchy food quality

Compared with three major cereals, underutilized cereals (UCs) are those with less use but having abundant bioactive components and better functionalities after proper processing. As a productive and energy-efficient technology, extrusion has been used for UC modification to improve its technological and nutritional quality. Extrusion could induce structural and quantitative changes in chemical components of UC flour, the degree of which is affected by extrusion intensity. Based on the predominant component (starch), functionalities of extruded underutilized cereal flour (EUCF) and potential mechanisms are reviewed. Considering bioactive compounds, it also summarizes the physiological functions of EUCF. EUCF incorporation could modulate the dough rheological behavior and starchy foods quality. Controlling extrusion intensity or incorporation level of EUCF is vital to achieve sensory-appealing and nutritious products. This paper gives comprehensive information of EUCF to promote its utilization in novel staple foods.

Image-based phenotyping of cassava roots for diversity studies and carotenoids prediction

Phenotyping to quantify the total carotenoids content (TCC) is sensitive, time-consuming, tedious, and costly. The development of high-throughput phenotyping tools is essential for screening hundreds of cassava genotypes in a short period of time in the biofortification program. This study aimed to (i) use digital images to extract information on the pulp color of cassava roots and estimate correlations with TCC, and (ii) select predictive models for TCC using colorimetric indices. Red, green and blue images were captured in root samples from 228 biofortified genotypes and the difference in color was analyzed using L*, a*, b*, hue and chroma indices from the International Commission on Illumination (CIELAB) color system and lightness. Colorimetric data were used for principal component analysis (PCA), correlation and for developing prediction models for TCC based on regression and machine learning. A high positive correlation between TCC and the variables b* (r = 0.90) and chroma (r = 0.89) was identified, while the other correlations were median and negative, and the L* parameter did not present a significant correlation with TCC. In general, the accuracy of most prediction models (with all variables and only the most important ones) was high (R2 ranging from 0.81 to 0.94). However, the artificial neural network prediction model presented the best predictive ability (R2 = 0.94), associated with the smallest error in the TCC estimates (root-mean-square error of 0.24). The structure of the studied population revealed five groups and high genetic variability based on PCA regarding colorimetric indices and TCC. Our results demonstrated that the use of data obtained from digital image analysis is an economical, fast, and effective alternative for the development of TCC phenotyping tools in cassava roots with high predictive ability.

Pulse-Cereal Blend Extrusion for Improving the Antioxidant Properties of a Gluten-Free Flour

Extrusion is an interesting technological tool that facilitates pulse formulation into flour mixtures, with tailored fibre content, total antioxidant capacity (TAC) and glycemic index (GI) among other components in final formulas. The gluten-free (GF) market has significantly grown during the last years. GF products have evolved from specialty health foods to products targeted to the general population and not only associated to celiac consumers. This study evaluates how temperature, cereal base (rice/corn) and pulse concentration affect extruded flour properties and which conditions are more efficient to develop a gluten-free flour with high TAC and low GI. Additionally, it evaluated the effect of this optimal formula after the baking process. The results showed an increase of total phenol (TP) and antioxidant activity with extrusion, with a temperature-dependent effect (130 °C ≥ 120 °C ≥ 110 °C), which may imply an enhanced bioaccessibility of phenolics compounds after extraction. Extrusion increased GI in comparison to native flour; however, a dough temperature of 130 °C resulted in a significantly (p ≤ 0.05) lower GI than that observed for 110-120 °C doughs, probably associated to the pastification that occurred at higher temperatures, which would decrease the degree of gelatinization of the starches and therefore a significant (p ≤ 0.05) GI reduction. Corn-lentil flour showed higher antioxidant properties and lower GI index in comparison with rice-lentil blends. The formulation of the optimal blend flour into a baked product (muffin) resulted in a significant loss of antioxidant properties, with the exception of the reducing power (FRAP), although the final antioxidant values of the baked product were in the range of the original native flour blend before any process.

Properties of Extruded Snacks Prepared from Corn and Carrot Powder with Ascorbic Acid Addition

The objective of this research was to investigate the potentiality of carrot powder (CP) utilization at levels 4, 6, or 8% as ingredient of corn snacks and evaluation of the extrusion influence on functionally important ingredients such as carotenoids (color), polyphenols, fiber, fat, and antioxidant activity. The influence of ascorbic acid (AA) as an external source at levels 0.5 and 1% on this particular extrusion was also investigated. A single-screw extruder at two temperature regimes (135/170/170 °C (E1) and 100/150/150 °C (E2)) carried out extrusion. The E1 temperature regime acted favorably on total polyphenol content and crude fiber, but fat preferred the E2 regime. Extrusion, especially the E1 temperature regime, increased the extractability of carotenoids. Ascorbic acid degraded during extrusion, but it still provided protection to carotenoids and color attributes of extrudates. Snacks with increased nutritional and functional value due to carrot powder addition were successfully produced, which is a starting point for production of a new type of extruded snacks.

Physical Characterization of Maize Grits Expanded Snacks and Changes in the Carotenoid Profile

The objective of this work was to evaluate the effects of feed moisture (13-17%, wb) and barrel temperature (120-160 °C) on physicochemical properties, and changes in the carotenoid profile of maize grits extruded snacks. The extrudates were obtained in a single-screw extruder, according to a 3² factorial design with two replicates. The linear coefficients of feed moisture and barrel temperature mainly affected the physicochemical properties. On the other hand, the interaction coefficient β₁₁₂ dominated the change in total carotenoids, lutein, zeaxanthin, and β-carotene. The quadratic coefficients were also important for changes in total color (regarding feed moisture), and for β-cryptoxanthin, specific mechanical energy, and volumetric expansion index (regarding barrel temperature). β-cryptoxanthin and β-carotene increased, whereas lutein and zeaxanthin decreased. The mathematical models developed from responses revealed two feasible operating regions under the domain explored. For a satisfactory process, from a technological and nutritional point of view, it is suggested to extrude at the operating conditions ranging between 13.2-13.7% feed moisture and 120-132 °C barrel temperature. Under these conditions, the specific mechanical energy input required was 410-450 kJ/kg, and extrudates with a volumetric expansion index greater than 12, a crispness work less than 0.4 N.mm, and with moderate increments in the levels of β-carotene and β-cryptoxanthin were produced. The use of richer cultivars in carotenoids could contribute to the production of healthier snacks.

Carotenoid content of extruded and puffed products made of colored-grain wheats

Wheat is a relevant source not only of essential macronutrients but also of many other health-promoting phytochemicals (carotenoids, anthocyanins, tocols, phenolic acids, etc.). Colored-grain wheats were used for extrusion and kernel puffing. The total content of carotenoids (sum of lutein, zeaxanthin, antheraxanthin, α- and β-carotene, and xanthophyll esters) decreased significantly due to extrusion (to 25.7%) and puffing (to 31.6%), compared to the content in the raw material. Zeaxanthin was shown to be the most stable among all detected carotenoids (30.8 and 48.7% was preserved). The results of the performed analyses have not confirmed greater stability of xanthophyll esters against higher temperatures (decrease to 29.5 and 22.1%). Both technologies induced E-to Z-isomerization of all-E-lutein and puffing also of all-E-zeaxanthin. Higher concentrations of 13-Z- and 9-Z-zeaxanthin were identified in puffed grains (2× and 37× on average). To preserve more carotenoids, it is appropriate to look for a more suitable food processing technology.

Carotenoids in Cereal Food Crops: Composition and Retention throughout Grain Storage and Food Processing

Carotenoids are C40 isoprenoids synthesized by plants, as well as some bacteria, fungi and algae, that have been reported to be responsible for a number of benefits conferred on human health. The inability of animals and humans to synthesize de novo these compounds is the reason why they must be introduced from dietary sources. In cereal grains, carotenoids are important phytochemicals responsible for the characteristic yellow colour of the endosperm, which confers nutritional and aesthetic quality to cereal-based products. Cereals are staple foods for a large portion of the world population, and the biofortification of cereal grains with carotenoids may represent a simple way to prevent many human diseases and disorders. Unfortunately, evidence exists that the storage and processing of cereal grains into food products may negatively impact their carotenoid content; so, this loss should be taken into consideration when analysing the potential health benefits of the cereal-based products. Focusing on the recent updates, this review summarizes the chemical composition of the carotenoids in the grains of staple cereals, including wheat, maize, rice and sorghum, the main factors that affect their carotenoid content during storage and processing and the most fruitful strategies used improve the grain carotenoid content and limit the carotenoid post-harvest losses.

Carotenoid changes of colored-grain wheat flours during bun-making

Colored-grain wheat genotypes were used in the preparation of flour, dough, buns, and buns stored for a short period of time. The main carotenoid in all genotypes was lutein, followed by its esters, zeaxanthin, and β-carotene, while antheraxanthin and α-carotene occurred only at negligible levels. The highest carotenoid contents were observed in yellow- and purple-grained genotypes. After the preparation of dough, total carotenoid content (TCC) decreased significantly by an average of 61.5%. Zeaxanthin was shown to be stable, whereas α-carotene was destroyed. In baked buns, the average decrease of TCC and all-E-lutein was lower than in unbaked dough. Greater decreases were recorded for esters, antheraxanthin, and β-carotene. After storing buns for 24 h at room temperature, approximately one-quarter of TCC observed in the original flour was preserved. Z-Isomers of lutein occurred in minor concentrations, but the degradation of this component, and that of zeaxanthin, was low, suggesting E- to Z-isomerization.

Significance of Genetic, Environmental, and Pre- and Postharvest Factors Affecting Carotenoid Contents in Crops: A Review

Carotenoids are a diverse group of tetraterpenoid pigments that play indispensable roles in plants and animals. The biosynthesis of carotenoids in plants is strictly regulated at the transcriptional and post-transcriptional levels in accordance with inherited genetic signals and developmental requirements and in response to external environmental stimulants. The alteration in the biosynthesis of carotenoids under the influence of external environmental stimulants, such as high light, drought, salinity, and chilling stresses, has been shown to significantly influence the nutritional value of crop plants. In addition to these stimulants, several pre- and postharvesting cultivation practices significantly influence carotenoid compositions and contents. Thus, this review discusses how various environmental stimulants and pre- and postharvesting factors can be positively modulated for the enhanced biosynthesis and accumulation of carotenoids in the edible parts of crop plants, such as the leaves, roots, tubers, flowers, fruit, and seeds. In addition, future research directions in this context are identified.

Carotenoid Stability during Dry Milling, Storage, and Extrusion Processing of Biofortified Maize Genotypes

Translation of the breeding efforts designed to biofortify maize ( Z. mays) genotypes with higher levels of provitamin A carotenoid (pVAC) content for sub-Saharan Africa is dependent in part on the stability of carotenoids during postharvest through industrial and in-home food processing operations. The purpose of this study was to simulate production of commercial milled products by determining the impact of dry milling and extrusion processing on carotenoid stability in three higher pVAC maize genotypes (C17xDE3, Orange ISO, Hi27xCML328). Pericarp and germ removal of biofortified maize kernels resulted in ∼10% loss of total carotenoids. Separating out the maize flour fraction (<212 μm) resulted in an additional ∼15% loss of total carotenoids. Carotenoid degradation was similar across milled maize fractions. Dry-milled products of Orange ISO and Hi27xCML328 genotypes showed ∼28% pVAC loss after 90-days storage. Genotype C17xDE3, with highest levels of all- trans-β-carotene, showed a 68% pVAC loss after 90-day storage. Extrusion processing conditions were optimal at 35% extrusion moisture, producing fully cooked instant maize flours with high pVAC retention (70-93%). These results support the notion that postharvest losses in maize milled fractions may be dependent, in part, on genotype and that extrusion processing may provide an option for preserving biofortified maize products.