Effect of different cooking methods on the polyphenol concentration and antioxidant capacity of selected vegetables

Impact of thermal processing on polyphenols, carotenoids, glucosinolates, and ascorbic acid in fruit and vegetables and their cardiovascular benefits

Bioactive compounds in fruit and vegetables have a positive impact on human health by reducing oxidative stress, inflammation, and the risk of chronic diseases such as cancer, cardiovascular (CV) diseases, and metabolic disorders. However, some fruit and vegetables must be heated before consumption and thermal processes can modify the amount of nutraceuticals, that is, polyphenols, carotenoids, glucosinolates, and ascorbic acid, that can increase or decrease in relation to different factors such as type of processing, temperature, and time but also the plant part (e.g., flower, leaf, tuber, and root) utilized as food. Another important aspect is related to the bioaccessibility and bioavailability of nutraceuticals. Indeed, the key stage of nutraceutical bioefficiency is oral bioavailability, which involves the release of nutraceuticals from fruit and vegetables in gastrointestinal fluids, the solubilization of nutraceuticals and their interaction with other components of gastrointestinal fluids, the absorption of nutraceuticals by the epithelial layer, and the chemical and biochemical transformations into epithelial cells. Several studies have shown that thermal processing can enhance the absorption of nutraceuticals from fruit and vegetable. Once absorbed, they reach the blood vessels and promote multiple biological effects (e.g., antioxidant, anti-inflammatory, antihypertensive, vasoprotective, and cardioprotective). In this review, we described the impact of different thermal processes (such as boiling, steaming and superheated steaming, blanching, and microwaving) on the retention/degradation of bioactive compounds and their health-promoting effects after the intake. We then summarized the impact of heating on the absorption of nutraceuticals and the biological effects promoted by natural compounds in the CV system to provide a comprehensive overview of the potential impact of thermal processing on the CV benefits of fruit and vegetables.

Quantitative Determination of Biogenic Element Contents and Phytochemicals of Broccoli (Brassica oleracea var. italica) Cooked Using Different Techniques

In this study, the effect of different cooking techniques on broccoli moisture, total phenolic, total flavonoid, and radical scavenging capacity results, polyphenol contents, and their quantitative values was investigated. The total phenolic quantities of fresh and cooked broccoli samples were assessed to be between 36.32 (conventional boiling) and 423.39 mg GAE/100 g (microwave heating). The radical scavenging activities of the broccoli samples were reported between 2.55 (conventional boiling) and 4.99 mmol/kg (microwave heating). In addition, catechin and rutin quantities of the fresh and cooked broccoli samples were measured to be between 2.24 (conventional boiling) and 54.48 mg/100 g (microwave heating), and between 0.55 (conventional boiling) and 16.33 mg/100 g (microwave heating), respectively. The most abundant elements in fresh and cooked broccoli samples were K, Ca, P, S, and Mg. The results showed some changes depending on cooking techniques compared to the control. The bioactive properties of broccoli samples cooked by means of conventional boiling, boiling in vacuum bag, and high-pressure boiling were established to be lower compared to the fresh sample. Catechin, 3,4-dihydroxybenzoic acid, rutin, and gallic acid were the key phenolic compounds of fresh and cooked broccoli samples. The phenolic components of broccoli were significantly affected by the applied cooking techniques. The highest protein in broccoli samples was determined in the broccoli sample cooked by boiling in a vacuum bag. There were statistically significant changes among the mineral results of broccoli cooked with different cooking methods.

Association between cooking patterns and the prevalence of hyperlipidemia in Eastern China

BACKGROUND

Hyperlipidemia is a major risk factor for many diseases. Previous studies have shown that diet is closely associated with hyperlipidemia. However, the relationship between cooking methods and hyperlipidemia remains unclear. The objective of this study was to identify the major cooking patterns existing in the Eastern Chinese population and evaluate their association with the prevalence of hyperlipidemia.

METHODS

We interviewed 4,710 residents in Eastern China regarding the consumption frequency of each cooking method when they prepare food at home or when eating out and regarding the prevalence of hyperlipidemia. Factor analysis, Chi-square tests, analysis of variance, and binary logistic regression analysis were used to identify the cooking patterns and analyze the characteristics of participants' categories of cooking patterns and the relationship between different cooking patterns and prevalence of hyperlipidemia.

RESULTS

Three major cooking patterns were identified: Traditional Chinese, Bland (little or no oil is used to process the food), and High-temperature cooking patterns. After controlling for potential confounders, participants in the highest quartile of the Bland cooking pattern had lower odds of hyperlipidemia than those in the lowest quartile. Nevertheless, no significant associations were observed between the Traditional Chinese and High-temperature cooking patterns and the prevalence of hyperlipidemia.

CONCLUSIONS

This study confirms the association between cooking patterns and the prevalence of hyperlipidemia and indicates that the Bland cooking pattern is associated with a reduced prevalence of hyperlipidemia.

Promoting healthy cooking patterns in China: Analysis of consumer clusters and the evolution of cooking pattern trends

Cooking methods can change the composition of foods and have important effects on human health. The Chinese people have developed many distinct and unique cooking methods. However, the daily cooking patterns of Chinese people and the characteristics and evolution of trends in cooking patterns commonly used by Chinese consumers remain unclear. The objective of this study was to identify the major cooking patterns and discuss their effects on human health, as well as to identify the cooking pattern consumer clusters and the evolution of trends in Chinese consumer cooking patterns. From March to June 2021, this study interviewed 4,710 residents in Eastern China regarding the consumption frequency of each cooking method when food is prepared at home or when eating out. Exploratory factor analysis, K-Means cluster analysis, Chi-square test, pairwise comparisons of multiple sample rates, and multivariate linear regression were used to identify the cooking patterns and cooking pattern consumer clusters, to assess differences in consumption preferences between consumer clusters, and to examine the relationship between demographic characteristic variables and different cooking patterns. Results revealed three major cooking patterns, namely traditional Chinese (cooking methods with native Chinese characteristics), bland, and high-temperature cooking patterns, as well as seven cooking pattern consumer clusters and their demographic characteristics in the Eastern Chinese population. With increases in age, education level, and income, consumers tended to choose the healthy "Bland" cooking pattern. Further, there was a higher proportion of people aged 36-65 years in the C3 cluster, which is characterized by the "Bland" cooking pattern. However, participants who were male and younger made fewer healthy choices in their cooking patterns. Specifically, a higher proportion of participants aged 21-35 years were found in the C5 cluster, which is characterized by the unhealthy "High-temperature" cooking pattern. Therefore, culinary health education should focus on individuals who are male and young. Specifically, the shift in cooking patterns among people aged 21-35 years should receive special attention.

Cooking at home to retain nutritional quality and minimise nutrient losses: A focus on vegetables, potatoes and pulses

Cooking at home has experienced a decline in many countries since the mid-20th century. As rates of obesity have increased, there has been an emphasis on more frequent home cooking, including its incorporation into several food-based dietary guidelines around the world as a strategy to improve dietary quality. With the recent trend towards the adoption of diets richer in plant-based foods, many consumers cooking at home may now be cooking plant foods such as vegetables, potatoes and pulses more often. It is, therefore, timely to explore the impact that different home cooking methods have on the range of nutrients (e.g. vitamin C and folate) and bioactive phytochemicals (e.g. carotenoids and polyphenols) that such plant foods provide, and this paper will explore this and whether advice can be tailored to minimise such losses. The impact of cooking on nutritional quality can be both desirable and/or undesirable and can vary according to the cooking method and the nutrient or phytochemical of interest. Cooking methods that expose plant foods to high temperatures and/or water for long periods of time (e.g. boiling) may be the most detrimental to nutrient content, whereas other cooking methods such as steaming or microwaving may help to retain nutrients, particularly those that are water-soluble. Dishes that use cooking liquids may retain nutrients that would have been lost through leaching. It may be helpful to provide the public with more information about better methods to prepare and cook plant foods to minimise any nutrient losses. However, for some nutrients/phytochemicals the insufficient and inconsistent research findings make clear messages around the optimal cooking method difficult, and factors such as bioaccessibility rather than just quantity may also be important to consider.

Impacts of polyphenols on laying hens' productivity and egg quality: A review

There has been a rapid increase in the world's output of main poultry products (meat and eggs). This reflects customer desire for these high-quality and safe products and the comparatively low price. Recently, natural feed additives, plants and products have been increasingly popular in the poultry and livestock industries to maintain and improve their health and production. Polyphenols are a type of micronutrient that is plentiful in our diet. They are phytochemicals that have health benefits, notably cardiovascular, cognitive function, antioxidant, anti-mutagenic, anti-inflammatory, antistress, anti-tumour, anti-pathogen, detoxification, growth-promoting and immunomodulating activities. On the other hand, excessive polyphenol levels have an unclear and sometimes negative impact on gastrointestinal tract health, nutrient digestion, digestive enzyme activity, vitamin, mineral absorption, laying hens performance and egg quality. As a result, this review illuminated polyphenols' various sources, classifications, biological activities, potential usage restrictions and effects on poultry, layer productivity and egg external and internal quality.

Hydrothermal Processing and In Vitro Simulated Human Digestion Affects the Bioaccessibility and Bioactivity of Phenolic Compounds in African Pumpkin (Momordica balsamina) Leaves

The African pumpkin (Momordica balsamina) contains bioactive phenolic compounds that may assist in reducing oxidative stress in the human body. The leaves are mainly consumed after boiling in water for a specific time; this hydrothermal process and conditions of the gastrointestinal tract may affect the presence and bioactivity of phenolics either positively or negatively. In this study, the effects of hydrothermal processing (boiling) and in vitro simulated human digestion on the phenolic composition, bioaccessibility and bioactivity in African pumpkin were investigated in comparison with those of spinach (Spinacia oleracea). A high-resolution ultra-performance liquid chromatography, coupled with diode array detection, quadrupole time-of-flight and mass spectrometer (UPLC-DAD-QTOF-MS) was used to profile phenolic metabolites. Metabolites such as 3-caffeoylquinic acid, 5-caffeoylquinic acid, 3,4-dicaffeoylquinic acid, 3,5-dicaffeoylquinic acid and 4,5-dicaffeoylquinic acid were highly concentrated in the boiled vegetable extracts compared to the raw undigested and all digested samples. The majority of African pumpkin and spinach extracts (non-digested and digested) protected Deoxyribonucleic acid (DNA), (mouse fibroblast) L929 and human epithelial colorectal adenocarcinoma (Caco-2) cells from 2,2'-Azobis(2-methylpropionamidine) dihydrochloride (AAPH)-induced oxidative damage. From these results, the consumption of boiled African pumpkin leaves, as well as spinach, could be encouraged, as bioactive metabolites present may reduce oxidative stress in the body.

Effects of Cooking and Processing Methods on Phenolic Contents and Antioxidant and Anti-Proliferative Activities of Broccoli Florets

We investigated the effects of cooking (steaming and microwaving) and processing (freeze-drying and hot-air-drying) methods on the antioxidant activity of broccoli florets. 2,2-diphenyl-1-picrylhydrazyl (DPPH^•), 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS^•), and alkyl^• free radical scavenging assays were employed to assess anti-oxidant potentials. The cytoprotective effect against oxidative damage induced by H₂O₂ was studied using hepatocellular carcinoma (HepG2) cells. Anti-proliferative effects were assessed in MCF-7 and MDA-MB-231 breast cancer cells. L-sulforaphane in broccoli extracts was quantified using high-performance liquid chromatography (HPLC). Steam and microwave treatments caused increases in total polyphenol content (TPC), whereas the total flavonoid content (TFC) decreased following steam treatment. A slight increase in TFC was observed in the microwaved samples. Extracts of all broccoli samples showed almost identical radical scavenging and cytoprotective effects. HPLC demonstrated that steamed (3 min)-freeze-dried (F-S3) and microwaved (2 min)-freeze-dried (F-M2) samples exhibited elevated levels of L-sulforaphane. In addition, the F-S3 and F-M2 extracts displayed strong anti-proliferative effects in MCF-7 cells, which correlated with L-sulforaphane content. As we observed no significant decrease in the antioxidant activity of broccoli florets, the cooking and processing methods and conditions studied here are recommended for broccoli.

Pomegranate By-Products as Natural Preservative to Prolong the Shelf Life of Breaded Cod Stick

This work evaluated the efficacy of pomegranate byproducts, specifically peel powder, as valid preservatives for food quality. Ready-to-cook cod sticks breaded with pomegranate peel powder were prepared. Shelf-life tests were conducted on breaded cod sticks during refrigerated storage (17 days) at 4 °C, monitoring the pH, microbiological and sensory quality. In addition, the nutritional quality of both the breaded and control samples was assessed. The results highlighted that active samples showed higher phenol and flavonoid content and higher antioxidant activity compared to the control fish, suggesting that pomegranate peel powder was responsible for a significant increase in cod stick nutritional quality. Furthermore, the cod stick active breading led to a delay in microbial growth without affecting the sensory properties; rather, it helped slow down the sensory attribute decline during the refrigerated storage. The data suggest that using pomegranate byproducts in breaded cod stick was effective in prolonging its shelf life, as well as improving its nutritional quality. Therefore, pomegranate peel powder can be considered as a potential resource as natural food preservative.

Food By-Products to Extend Shelf Life: The Case of Cod Sticks Breaded with Dried Olive Paste

Recently, the interest in recovery bioactive compounds from food industrial by-products is growing abundantly. Olive oil by-products are a source of valuable bioactive compounds with antioxidant and antimicrobial properties. One of the most interesting by-products of olive oil obtained by a two-phase decanter is the olive paste, a wet homogeneous pulp free from residuals of the kernel. To valorize the olive paste, ready-to-cook cod sticks breaded with dried olive oil by-products were developed. Shelf-life tests were carried out on breaded cod sticks and during 15 days of storage at 4 °C pH evolution, microbiological aspects, and sensory properties were also monitored. In addition, the chemical quality of both control and active samples was assessed in terms of total phenols, flavonoids, and antioxidant activity. The enrichment with olive paste increased the total phenols, the flavonoids, and the antioxidant activity of the breaded fish samples compared to the control. Furthermore, the bioactive compounds acted as antimicrobial agents, without compromising the sensory parameters. Therefore, the new products recorded a longer shelf life (12 days) than the control fish sample that remained acceptable for nine days.

Paper microzone plate based on DPPH as a simple colorimetric assay of the total antioxidant content of herbal extracts

The human body needs an antioxidant-rich diet that comes from foods, beverages, and herbal products to support the physiological antioxidant systems. Thus, the development of an analytical tool for a simple assay of the total antioxidant capacity (TAC) of the rich antioxidant samples is crucial. The current work demonstrates a simple colorimetric assay of TAC of the herbal extract on the paper microzone plate (PµZP) that was constructed in the 70-well of patterned paper using the screen printing technique. The PµZP was constructed by immobilizing DPPH (2,2-diphenyl-1-picrylhydrazyl) onto 70-well of PµZP as a sensing zone for colorimetric detection. The purple-sensing zone exhibited a good response to gallic acid (GA), by producing slightly gray to pale yellow color that can be captured using a scanner and then analyzed using the ImageJ program. The paper-based sensor showed a linear response toward GA at 0.05-0.6 mM (r = 0.9895), reproducible response (RSD < 4%), and accurate measurement with 91 to 106% recovery for measuring TAC of herbal extract, presented as mM gallic acid equivalent and showed a good agreement with the standard DPPH method. The results suggested that the proposed method can be applied for simple TAC measurement in the herbal extract.

Application and optimisation of air-steam cooking on selected vegetables: impact on physical and antioxidant properties

BACKGROUND

Several studies investigated the impact of different cooking techniques on the quality of vegetables. However, the use of the combined air-steam cooking is still scarcely debated, despite the advantages informally referred by professional catering workers. In this study, its optimisation was studied on Brussels sprouts and pumpkin cubes to obtain the best physical (texture, colour) and antioxidant (FRAP, total phenols) response, in comparison to a conventional steaming treatment.

RESULTS

Increasing the strength of the air-steam treatment, Brussels sprouts resulted to be softer, less green (higher a* value), richer in phenols and exhibited lower FRAP values than the steamed ones. The air-steamed pumpkin cubes exhibited an equivalent softening degree to that of steamed ones and, under the strongest cooking conditions, a higher antioxidant quality and a yellow darkening (lower b* value). Varying the cooking time and/or temperature, a linear change of force/compression hardness and a* (negative a*: greenness) for Brussels sprouts, b* (yellowness) and total phenol content for pumpkin cubes was observed. A predictive model for these variables was obtained by response surface methodology. The best process conditions to achieve the optimal desirability were also identified.

CONCLUSION

The application of air-steam cooking under suitable time/temperature conditions could be proposed as an alternative method to a traditional steam cooking on Brussels sprouts and pumpkin cubes, being able to preserve or improve their quality. The best air-steam cooking conditions were 25 min at 90 °C for Brussels sprouts and 10 min at 110 °C for pumpkin. © 2017 Society of Chemical Industry.

Efficacy of Combined Sous Vide-Microwave Cooking for Foodborne Pathogen Inactivation in Ready-to-Eat Chicory Stems

There is a variety of different food processing methods, which can be used to prepare ready-to-eat foods. However, the need to preserve the freshness and nutritional qualities leads to the application of mild technologies which may be insufficient to inactivate microbial pathogens. In this work, fresh chicory stems were packed under a vacuum in films, which were transparent to microwaves. These were then exposed to microwaves for different periods of time. The application of sous vide microwave cooking (SV-MW, 900 W, 2450 MHz), controlled naturally occurring mesophilic aerobic bacteria, yeasts and molds for up to 30 d when vacuum-packed vegetables were stored at 4 °C. In addition, the process lethality of the SV-MW 90 s cooking was experimentally validated. This treatment led to 6.07 ± 0.7 and 4.92 ± 0.65 log cfu/g reduction of Escherichia coli and Listeria monocytogenes inoculated over the chicory stems (100 g), respectively. With an initial load of 9 log cfu/g for both pathogens, less than 10 cfu/g of surviving cells were found after 90 s cooking. This shows that short-time microwave cooking can be used to effectively pasteurize vacuum-packed chicory stems, achieving >5 log cfu/g reduction of E. coli and L. monocytogenes.

Scanometry as microplate reader for high throughput method based on DPPH dry reagent for antioxidant assay

The stable chromogenic radical 1,1'-diphenyl-2-picrylhydrazyl (DPPH) solution was immobilized on the microwell plate as dry reagent to construct a simple antioxidant sensor. Then, a regular flatbed scanner was used as microplate reader to obtain analytical parameters for antioxidant assay using one-shot optical sensors as scanometry technique. Variables affecting the acquisition of the images were optimized and the analytical parameters are obtained from an area of the sensing zone inside microwell using the average luminosity of the sensing zone captured as the mean of red, green, and blue (RGB) value using ImageJ^® program. By using this RGB value as sensor response, it is possible to determine antioxidant capacity in the range 1-25 ppm as gallic acid equivalent (GAE) with the response time of 9 min. The reproducibility of sensor was good (RSD<1%) with recovery at 93%-96%. The antioxidant sensor was applied to the plant extracts, such as sappan wood and Turmeric Rhizome. The results are good when compared to the same procedure using a UV/Vis spectrophotometer.

Simultaneous Extraction and Identification of Phenolic Compounds in Anoectochilus roxburghii Using Microwave-Assisted Extraction Combined with UPLC-Q-TOF-MS/MS and Their Antioxidant Activities

This study used MAE and RSM to extract phenolic compounds from Anoectochilus roxburghii, and the optimum conditions defined by the model to give an optimum yield of 1.31%. The antioxidant activity in vitro showed when the concentration of phenolic compounds was reached 1 mg mL^-1, the clearance rates were 82.58% for DPPH and 97.62% for ABTS⁺. In vivo antioxidant experiments used D-galactose to build oxidative damage in healthy Kunming mice. The result showed that the extractions of A. roxburghii can improve the antioxidant ability and the medium and low dose groups had better ability to scavenge free radicals. The UPLC-Q-TOF-MS/MS was developed to identify 21 kinds of phenolic compounds by molecular mass, ms/ms fragmentation, as well as retention time. The result showed that the phenolic compounds of A. roxburghii had significant potential as a natural antioxidant to promote health and to reduce the risk of disease.

Effect of Steaming and Boiling on the Antioxidant Properties and Biogenic Amines Content in Green Bean (Phaseolus vulgaris) Varieties of Different Colours

Effects of boiling and steaming cooking methods were studied on total polyphenols, antioxidant capacity, and biogenic amines of three green bean varieties, purple, yellow, and green. The vegetables gave good values both for antioxidant capacity and for phenolics content, with the purple variety being the richest in healthful components. Both the heat treatments affected the antioxidant properties of these vegetables, with boiling that reduced the initial antioxidant capacity till 30% in the yellow variety, having the same trend for total polyphenols, with the major decrement of 43% in the green variety. On the contrary, biogenic amines significantly increased only after boiling in green and yellow variety, while purple variety did not show any changes in biogenic amines after cooking. The steaming method showed being better cooking approach in order to preserve the antioxidant properties of green beans varieties and to maintain the biogenic amines content at the lowest level.