Over the last few decades, the improvement of tomato aroma and flavour has gained growing attention among breeders, agronomists and food technologists, as it is reputed as a key tool to further consolidate tomato consumption in the global market. However, this represents a difficult task, since more than 400 volatile organic compounds (VOCs) differently contribute to tomato aroma and its flavour perception. The recent development of molecular tools has allowed us to identify some of the major alleles influencing the volatile composition of tomatoes. Nonetheless, such composition involves an intricate weave of polygenic systems, highly influenced by external, pre and postharvest factors. With few exceptions, our knowledge about the effects of these determinants is still scarce, making it difficult to draw sound conclusions to best manage the future genetic potential. The present review examines the existing knowledge on major VOCs influencing tomato organoleptic quality, including their classification, metabolic pathways, genetics, and technical features that affect their concentrations in fruits. Particular emphasis is placed on preharvest and postharvest factors influencing their quantitative and qualitative expression, whose integrated study with omic tools will be increasingly necessary for the perspective of disseminating reliable operational indications throughout the production/distribution chain.
23 October 2019 in South African Journal of Clinical Nutrition
Objective: To determine the micronutrient composition of fresh and boiled traditional green leafy vegetables (TGLVs). Design: Sixteen TGLVs categorised into cultivated and uncultivated vegetables were analysed for vitamin C (ascorbic acid [AA] and dehydroascorbate [DHAA]), β-carotene, lutein and minerals. Results: Basella alba had the highest AA (72 mg/100 g) content; Vernonia amygdalina (unwashed), had the highest β-carotene and lutein concentrations (14.1 and 29.0 mg/100 g, respectively); Amaranthus hybridus had the highest AA (43 mg/100 g) and β-carotene (9.3 mg/100 g) content, for cultivated sp. Celosia argentea had the highest Fe content; Zn content of all the vegetables was low, 0.4–2.6 mg/100 g. Cooking resulted in significant losses in AA content in all the samples, 19% in B. alba to 100% in Crassocephalum crepidioides. Carotenoid losses were observed in 10 samples and six samples had increased values of β-carotene (12% to 183%) and lutein (64% to double). Conclusion: Traditional green leafy vegetables studied were found to be rich in the micronutrients of interest, especially in carotenoids. Boiling of leafy vegetables, as traditionally done, led to considerable losses of the micronutrients. The micronutrient content of uncultivated leafy vegetables compared well with commonly cultivated species.
The texture of tomato products can be modified by choice of variety, their growing conditions and/or processing method, but no clear explanation exists of the mechanisms that transform fruit tissue, how they act on texture, or whether genetics and processing impact the same physical parameters. We therefore conducted a study that processed 4 varieties produced under low/high nitrogen supply, into puree using both hot and cold break processes. No specific rheological signature allows discrimination between cultivar-induced or process-induced textural changes, but that they can be distinguished by sensory analysis. Growth conditions impacted but was not sensory distinguished. Both caused significant variations in 7 of 11 physico-chemical parameters, but the order of importance of these traits controlling texture varied, depending on whether the cause was genetic or process-related. Analysis of alcohol insoluble solids revealed a specific signature in pectin composition and conformation that could be linked to particle aggregation in the presence of lycopene-rich particles.
24 October 2019 in South African Journal of Clinical Nutrition
Objective: To determine the consumption pattern of selected households consuming traditional green leafy vegetables (TGLVs) during three seasons and potential contribution to recommended nutrient intakes. Design: Repeated household survey using food frequency questionnaire to obtain consumption pattern of selected TGLVs. Setting and Subjects: Selected households in a small rural farming community: pre-rainy (n = 43), rainy (n = 36) and post-rainy seasons (n = 40). Results: Corchorus olitorius and A. hybridus were the most consumed by > 70% of households across three seasons. A. esculentus and A. viridis were the least consumed TGLVs through all the seasons. Uncultivated and cultivated TGLVs could contribute between 26–> 100% and 18–96%, respectively, of recommended intake for vitamin A for children and women. For young children, both the cultivated and uncultivated TGLVs could contribute more than 50% of their RDA for iron. Conclusion: seasonal availability, and preference for certain species, determine the consumption pattern of the TGLVs studied. Uncultivated and less utilised vegetables have the potential to make significant contributions to the micronutrient requirements of women and children, especially vitamin A and iron if frequently used.