Preferences for steaming of vegetables

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.

'Old Is Gold': How Traditional Indian Dietary Practices Can Support Pediatric Diabetes Management

Nutrition is crucial for maintaining normal growth, development, and glycemic control in young people with diabetes (PwD). Undue restrictions cause nutrient deficiencies as well as poor adherence to meal plans. Widespread availability of low-cost, ultra-processed, and hyperpalatable food is further damaging. Most families struggle to find ways to provide nutritious, yet attractive, food with a low glycemic index (GI). India is one of the oldest continuous civilizations with a rich and diverse cultural and culinary heritage. Traditional dietary practices, including the centuries-old 'Thali' (meaning plate) concept, emphasize combinations (grains, lentils, vegetables, dairy, spices, prebiotics and probiotics, and fats) of local, seasonal, and predominantly plant-based ingredients. These practices ensure that all of the necessary food groups are provided and fit well with current evidence-based recommendations, including the International Society for Pediatric and Adolescent Diabetes (ISPAD) 2018 Guidelines. Techniques for the preparation, cooking, and preservation of food further impact the GI and nutrient availability. These practices benefit nutrient density, diet diversity, and palatability and thus improve adherence to meal plans and glycemic control. This narrative review describes the ancient wisdom, food composition, and culinary practices from across India which are still valuable today. These may be of benefit worldwide to improve glycemic control as well as quality of life, especially in PwD.

Influence of Cooking Conditions on Nutritional Properties and Sensory Characteristics Interpreted by E-Senses: Case-Study on Selected Vegetables

This study investigates the effects of three cooking methods (boiling, steaming and microwaving) on the nutritional and physical properties of cauliflowers, carrots and sweet potatoes; e-senses were applied to interpret the sensory characteristics according to physico-chemical aspects. The nutritional quality was evaluated by determining the concentrations of key components and the antioxidant activity; e-sense data, combined with texture parameters, were processed by a principal component analysis. The cooking method and time significantly influenced the quality of the three products. Boiling, which detrimentally affected ascorbic acid, total phenolic concentration and antioxidant activity, enhanced carotene accessibility. Steaming produced losses in ascorbic acid, increasing total phenolics and carotenoids. Microwaving resulted in minor changes in ascorbic acid concentrations, preserved carotenoids and increased total phenolics. The nutritional quality was better preserved or enhanced using shorter cooking times. The elaboration of the data collected by the e-senses showed a clear evolution according to the cooking method and time. The results helped to determine the cooking method that best preserves the nutritional properties of the vegetables, highlighting the applicability of rapid instrumental methods to interpret the evolution of sensory characteristics.

Effects of domestic cooking on flavonoids in broccoli and calculation of retention factors

The flavonoid contents in vegetables are strongly influenced by domestic cooking. The objective of this study was to evaluate the effects of domestic cooking on the structurally complex flavonoids in broccoli. Raw broccoli was cooked by boiling, steaming and microwaving. Seven kaempferol (Km) glycosides and one quercetin (Qn) glycoside were identified and quantified in raw and cooked broccoli by HPLC-MS. Boiling resulted in significant loss of all flavonoids, while steaming and microwaving led to minor loses or even increases of the flavonoids. Apparent retention factors (AR) and true retention factors (TR) were calculated for individual flavonoids. AR ranged from 35.6% to 147.5% and TR ranged from 30.4% to 174.1%, respectively, depending on the cooking method and chemical structures of flavonoids. Two different ways to calculate total retention factors, "Retention Factor by Glycoside" and "Retention Factor by Aglycone", were also calculated. In conclusion, domestic cooking significantly altered the flavonoid contents in broccoli, with cooking method and chemical nature being key influential factors. Acylated Km tri- or tetra-glycosides appeared to be more resistant to domestic cooking.

How Do Cooks Actually Cook Vegetables? A Field Experiment With Low-Income Households

Vegetables in the diet contribute to disease prevention. However, low-income households underconsume fresh vegetables, perhaps because of cost and of unavailability at nearby stores. A third reason may lurk behind those barriers: cooks’ unfamiliarity with various and appealing ways to prepare vegetables. To illuminate that possibility and to suggest interventions that could be designed more effectively to boost vegetable consumption, this study took the novel step of providing ample, if temporary, supplies of a fresh vegetable to random sets of clients of food pantries. A week later, telephone interviews obtained details about preparations of meals and snacks that household cooks had made with their unexpected bounty. Among the experiment’s 10 vegetables, some were used twice as often as others. Even more striking, cooks practiced a narrow repertoire of preparation methods, dominated by boiling and steaming, across most of the vegetables. Fats and salt were often added to boiled and steamed preparations. Implications are drawn to suggest kinds of recipes—pairings of vegetables and of vegetables with underused means of preparation—that could expand cooks’ repertoires and add variety in flavors, appearances of dishes, meal textures, and aromas.

Evaluation of different cooking conditions on broccoli (Brassica oleracea var. italica) to improve the nutritional value and consumer acceptance

The objective of this study was to gain insights into the effect of the cooking method on the liking as well as the retention of glucosinolates in broccoli. With this knowledge it can be concluded whether the health aspects of broccoli be improved by the cooking method without deteriorating sensory perception. For this, broccoli was cooked by methods commonly applied by consumers: boiling with a cold (water) start; boiling with a hot (water) start; and steaming. Firmness, greenness and amount of total glucosinolates in cooked broccoli were instrumentally determined. Sensory evaluation by untrained consumers (n = 99) for liking and sensory attributes intensity rating were performed on broccoli cooked by steaming and boiling-cold start at three time points, which resulted in 'high', 'medium', 'low' firm broccoli samples. At the end of cooking, steaming showed an increase in the amount of total glucosinolates (+17%). Boiling-hot start (-41%) and boiling-cold start (-50%) showed a decrease in amount of total glucosinolates. Sensory evaluation did not show statistically significant differences between steaming and boiling-cold start in liking at 'high' and 'medium' firmness; and in the attribute intensity ratings (except for juiciness at 'medium' firmness, and flavour at 'medium' and 'low' firmness). This study demonstrates that medium firm broccoli showed optimum liking and that steaming compared to boiled-cold start showed higher amount of glucosinolates. It is concluded that the health aspects of broccoli can be improved without reducing the sensory aspects by optimising the cooking method.

Sensory and health properties of steamed and boiled carrots (Daucus carota ssp. sativus)

This study examined the influences of domestic processing conditions applied by consumers on firmness, colour and amount of phytochemicals and liking and sensory attributes intensity rating of carrots. The aim was to identify a cooking method and time that yields carrots with higher amount of β-carotene while maintaining consumer liking. Instrumentally measured firmness and colour showed comparable degradation trends between cooking methods. While boiling showed a significant decrease in the amount β-carotene after 20 min (-19%), steaming maintained the amount (+40%). Cooking method did not show a significant effect on liking and intensity ratings for the majority of the sensory attributes. Medium firm carrots were liked the most and low firm carrots the least. This study demonstrates that for optimum liking, carrots should be in the range of medium firmness. This can be obtained through either cooking methods but steamed carrots possess a higher amount of β-carotene and maintains liking.