The effects of cooking method on selected quality traits of broccoli and green asparagus

Effects of different processing methods on the functional, nutritional, and physicochemical profiles of cowpea leaf powder

Indigenous fruits and vegetables can improve food security and biodiversity. However, their use is hindered by perishability, seasonal availability, cooking losses, lack of nutritional composition data, and connections to low socioeconomic status. This study aimed to process cowpea leaves into powder and determine the effect of five home-cooking methods on their protein, functional, physicochemical, and heavy metal profiles. Cowpea leaves were boiled, blanched, steamed, sous-vide cooked, and stir-fried, at 5, 10, and 15 min before dehydration at 60°C. Cowpea leaves contain protein up to 20 g/100 g. The leaves are rich in calcium, potassium, and zinc, providing up to 70% of the adult recommended dietary allowance for calcium and potassium per 100 g of powder. Cowpea leaf powder exhibited good water/oil absorption and rehydration capacities. Sous-vide and steamed cowpea leaves provided an overall superior nutritional profile (p ≤ 0.05). Heavy metals in the cowpea leaf powders were below the WHO permissible limits except for aluminum and high arsenic levels. This study demonstrated that cowpea leaf powders could be potentially incorporated into foods to improve functional properties and nutrient intake.

Nutritional Profile and Chlorophyll Intake of Collard Green as a Convenience Food

Background/Objectives: Collard green (Brassica oleracea var. viridis) is widely cultivated for its adaptability and nutritional benefits. This study examines the nutritional composition and chlorophyll content of the "Couve-Manteiga" cultivar grown in Italy, emphasizing its potential application in convenience foods, such as fresh-cut, fifth-range, and freeze-dried products, to enhance chlorophyll intake in the population. Methods: The leaves of collard greens were analyzed for proximate composition, mineral content, amino acid and fatty acid profiles, and chlorophyll levels. Chlorophyll retention was measured after sous vide cooking and freeze-drying to assess the efficacy of these preservation methods. The chlorophyll content of different product formats was quantified, and potential dietary contributions were estimated based on consumption data. Results: Collard greens exhibited a low caloric value (30.66 kcal/100 g), with high levels of dietary fiber (3.39 g/100 g), protein (3.01 g/100 g), calcium (333.09 mg/100 g), and potassium (215.53 mg/100 g). The amino acid profile revealed an essential to non-essential amino acid ratio of 0.72. Chlorophyll retention was notably high in both freeze-dried (97.66%) and sous-vide cooked products (83.5%), indicating the effectiveness of these methods in preserving chlorophyll content compared to fresh-cut leaves. Conclusions: The results suggest that convenience foods made from collard green leaves provide an accessible means to boost chlorophyll intake and enhance daily nutrition, offering a practical solution for increasing the consumption of this nutrient-rich vegetable.

Effect of Different Cooking Methods on the Aroma and Taste of Chicken Broth

A single combi oven, known for its versatility, is an excellent choice for a variety of chicken soup preparations. However, the impact of universal steam ovens on the flavor quality of chicken soup remains unclear. This study aimed to explore the impact of different cooking methods on the aroma and taste of chicken soup. Three cooking methods with various stewing times were compared: ceramic pot (CP), electric pressure cooker (EPC), and combi oven (CO). Analyses were conducted using electron-nose, electron-tongue, gas chromatography-ion mobility spectrometry (GC-IMS), automatic amino acid analysis, and chemometric methods. A total of 14 amino acids, including significant umami contributors, were identified. The taste components of CP and CO chicken soups were relatively similar. In total, 39 volatile aroma compounds, predominantly aldehydes, ketones, and alcohols, were identified. Aldehydes were the most abundant compounds, and 23 key aroma compounds were identified. Pearson's correlation analyses revealed distinct correlations between various amino acids (e.g., glutamic acid and serine) and specific volatile compounds. The aroma compounds from the CP and CO samples showed similarities. The results of this study provide a reference for the application of one-touch cooking of chicken soup in versatile steam ovens.

Physical character, total polyphenols, anthocyanin profile and antioxidant activity of red cabbage as affected by five processing methods

Understanding the influence of processing methods on the phytochemicals of fruits and vegetables is of importance in retaining the health-benefiting properties of those products. The aim of this study was to investigate the effects of five processing methods including freeze drying (FD), hot air drying (HD), water boiling (WB), steaming (ST), and pickling (PI) on the physical character, total polyphenols, anthocyanin profile and antioxidant activity of red cabbage. Different color and texture were observed after different processing methods. Total anthocyanin content was reduced by 73%, 72%, 41%, 16%, and 30% in FD, HD, WB, ST and PI processed red cabbage, respectively. PI samples showed the highest values of total polyphenols and DPPH scavenge activity among all the processed red cabbage. Both FD and HD samples had relatively low values of total polyphenols and DPPH scavenge activity. However, FD sample had the highest FRAP values. UPLC-QqQ-MS/MS analysis showed that fresh red cabbage contained 22 anthocyanins among which cyanidin-3-diglucoside-5-glucoside was the prominent. Compared with drying process, WB, ST and PI decreased the loss of most of the anthocyanin component in red cabbage. Correlation analysis indicated that antioxidant capacity as determined by DPPH of red cabbage was positively and significantly correlated with the total anthocyanins. This study suggested that drying induced significant loss of phytochemicals in red cabbage, and WB, ST, as well as PI were advisable ways for daily consumption of red cabbage considering the bioactive components. Especially, ST was the best way to retain anthocyanins in red cabbage.

Effects of Different Processing Methods on the Quality and Physicochemical Characteristics of Laminaria japonica

The effects of four domestic cooking methods, including blanching, steaming, boiling, and baking treatments, on processing properties, bioactive compound, pigments, flavor components, and tissue structure of Laminaria japonica were investigated. The results showed that the color and structure of kelp changed most obviously after baking; steaming was most beneficial in reducing the color change of the kelp (ΔE < 1), while boiling was most effective in maintaining the texture of the kelp (its hardness and chewiness were close to that of raw kelp); eight volatile compounds were detected in raw kelp, four and six compounds were detected in blanched and boiled kelp, while eleven and thirty kinds of compounds were detected in steamed and baked kelp, respectively. In addition, the contents of phloroglucinol and fucoxanthin in kelp after the four processing methods were significantly reduced (p < 0.05). However, of all the methods, steaming and boiling were the best at preserving these two bioactive substances (phloroglucinol and fucoxanthin) in kelp. Therefore, steaming and boiling seemed more appropriate to maintain the original quality of the kelp. Generally, to improve the sensory characteristics of each meal of Laminaria japonica and to maximize the retention of active nutrients, several different processing methods are provided according to the respective effects.

Effects of different processing methods on the polyphenolic compounds profile and the antioxidant and anti-glycaemic properties of horseradish roots (Armoracia rusticana)

Horseradish (Armoracia rusticana) provides human organisms with various effective treatments for improving human health, and it constitutes a salubrious root used for culinary purposes. This outcome derives from the chemical composition and polyphenols content of horseradish. This study's objective was to determine individual polyphenols, total phenolic (TPC) and total flavonoid (TFC) contents, colour parameters, inhibition of advanced glycation end product (AGEs) formation and Trolox Equivalent Antioxidant Capacity (TEAC) by DPPH and ABTS of horseradish products. Phenolic acids and flavonoids were analysed by HPLC-DAD-MS method. Horseradish products were obtained by thermal treatments such as boiling, baking and sous-vide. Fresh and sous-vide samples were characterized by the most abundant TPC values, whereas TFC horseradish indicated the highest value after boiling treatment. Moreover, the highest values of antioxidant capacity in fresh horseradish roots were detected. Flavonoids presented lower concentrations than phenolic acids, while syringic acid was the most abundant phenolic compound. Horseradish, after sous-vide treatment, appeared to have a higher inhibition of AGEs formation. Thermal treatment of horseradish root increased the saturation of yellow (b*) and red (a*) colours and decreased colour brightness. Our findings indicate that horseradish products are a valuable source of polyphenols, with their profile, content, and antioxidant and anti-AGEs formation activity modulated by applied processes.

Microwave bag cooking affects the quality, glucosinolates content and hydrolysate production of broccoli florets

Appropriate processing and cooking technologies can effectively improve the content of bioactive compounds in vegetables. The effects of microwave bag cooking on broccoli floret quality attributes, glucosinolates (GLSs) content and hydrolysate production were investigated in this study. Microwave bag cooking not only preserved the color of the florets, but also enhanced the total phenolic and flavonoid content, as well as total chlorophyll and ascorbic acid content. Furthermore, the majority of the microorganisms were inactivated, and the structure of the florets was greatly destroyed, thereby increasing antioxidant capacity and promoting the release of GLSs and myrosinase activity in the florets. Moreover, microwave bag cooking significantly enriched the sulforaphane (SFN) and indole-3-carbinol (I3C) production of broccoli florets in the meantime, demonstrating that it was a convenient and quick cooking option to satisfy the requirements of modern consumers.

A comprehensive study for taste and odor compounds using electronic tongue and nose in broccoli stem with different thermal processing

This study analyzed taste and odor profiles in broccoli stems with different methods of thermal processing using electronic tongue and electronic nose. In electronic tongue analysis, umami and bitterness were obviously changed upon thermal processing, however, saltiness, sweetness, and sourness showed slight variations. Between raw and thermally processed broccolis, microwaved broccoli showed the highest changes of tastes based on raw broccoli, however, blanched broccoli showed similar tastes to raw broccoli compared with the others. In electronic nose analysis, a total of 21 volatiles in broccolis were analyzed. Sulfur-containing volatiles were changed via thermal steps, and the generation and reduction of sulfur-containing compounds have occurred (i.e. methnaethiol, 2,4,5-trimethylthiazole). In addition, some of the thermal steps (oven-heating, microwave heating, air-frying) have occurred Maillard reaction, and thus pyridine was generated. Therefore, this study can provide flavor data in broccoli, and contribute to further research for flavor characteristics in broccoli using electronic sensors.

Modeling Softening Kinetics at Cellular Scale and Phytochemicals Extractability in Cauliflower under Different Cooking Treatments

The effects induced by heat on Depurple and Cheddar (Brassica oleracea L. var. botrytis) during boiling, steaming, and sous-vide were investigated to elucidate the role of the basic cellular elements in softening and extractability of sterols and tocopherols. With this aim, an elastoplastic mechanical model was conceptualized at a cell scale-size and validated under creep experiments. The total amount of the phytochemicals was used to validate multivariate regression models in forecasting. Boiling was the most effective method to enhance the softening mechanisms causing tissue decompartmentalization through cell wall loosening with respect to those causing cell separation, having no impact on the phytochemical extractability. Sous-vide showed the lowest impact on cell wall integrity, but the highest in terms of cell separation. Steaming showed an intermediate behavior. Tissue of the Depurple cauliflower was the most resistant to the heat, irrespectively to the heating technology. Local heterogeneity in the cell wall and cell membrane, expected as a plant variety-dependent functional property, was proposed as a possible explanation because sterol extractability under lower heat-transfer efficiency, i.e., steaming and sous-vide, decreased in Depurple and increased in Cheddar as well as because the extractability of sterols and tocopherols was greater in Cheddar.

Nutritional and Phytochemical Composition of Mediterranean Wild Vegetables after Culinary Treatment

Studies are scarce on the nutritional and phytochemical composition of wild edible Mediterranean plants after culinary processing. This work provides the nutritional composition after culinary treatment (including dietary fiber and mineral composition) and bioactive compounds (folates, vitamin C and organic acids) of wild Rumex pulcher L., Silene vulgaris (Moench) Garcke. leaves, and wild Asparagus acutifolius L., Bryonia dioica Jacq., Humulus lupulus L., Tamus communis L. young shoots. Shoots better preserved their nutrients than leaves, due to their different tissue structure. Fresh and cooked wild greens present high dietary fiber values, and remained at remarkable levels after boiling. Na, K, Mg and Zn were lost in about 50% due to culinary processing, while Ca, Cu, Fe and Mn were more stable. Boiled leaves of S. vulgaris remained as a good Mn source. A portion of 100 g of most of the cooked analyzed species could cover a relevant percentage of the daily requirement of folates (R. pulcher and A. acutifolius providing more than 80%) and vitamin C (T. communis and A. acutifolius providing more than 35%).

Impact of moist cooking methods on colour, anti-nutritive compounds and phenolic metabolites in African nightshade (Solanum retroflexum Dun.)

Not much information is available on the changes of phenolic metabolites or anti-nutritive compounds in African nightshade leaves during moist cooking. Blanching methods (boiling, microwave, and steaming) using 5-20% lemon juice was compared with the plain water as a control. Lemon juice at 20% significantly increased the total colour differences (ΔE). Chlorophyll content and the overall acceptance were highest for samples steamed in 5% lemon juice. Steam blanching in plain water reduced the tannin, oxalate and phytate contents but showed higher comparative peak responses for steroidal saponins. Neochlorogenic, chlorogenic, and caffeoylmalic acid, kaempferol O-rhamnosyl hexoside, and rutin were identified blanched leaves. Principle component analysis (PCA) discriminated between blanching treatments while Orthogonal Projections to Latent Structures Discriminant Analysis (OPLS-DA) showed clear group distinctions between the blanching treatments. Chlorogenic acid, neochlorogenic acid and cryptochlorogenic acid were the responsible biomarkers for the separation of the steam blanching treatments. Thus, steam blanching preserves the functional compounds in nightshade leaves.