The use of natural media amendments to produce kale enhanced with functional lipids in controlled environment production system.

Diets high in vegetable consumption is highly correlated with reduced risk of developing common lifestyle related diseases. We investigated the effects of three natural growth media amendments [potassium humate, dry vermicast, volcanic minerals or Promix alone (Control)] in enhancing the accumulation of functional lipids in greenhouse grown kale. Functional lipids (n9, n6, n3 fatty acids, diglycerides, galactolipids and phytosterols) were assessed using either gas chromatography/mass spectrometry (GC/MS) or ultra-high performance liquid chromatography-high resolution tandem mass spectrometry (UHPLC-HRMS/MS). The results showed volcanic minerals and dry vermicast were the most successful in enhancing the accumulation of functional lipids in kale. For example, dry vermicast enhanced the accumulation of total C18:1n9 and C16:3n3 fatty acids, while total C18:2n6 fatty acid accumulation was enhanced by volcanic minerals. In conclusion, natural growing medium amendments are remarkably effective in modulating the accumulation of functional lipids in kale grown under controlled-environment conditions. This could be a useful strategy for functional foods production in control environment production systems. Increase access to kale with enhanced functional lipids could aid in increase consumption of these health promotive compounds in the diet with potential implications in population health.

Chemical composition of kale as influenced by dry vermicast, potassium humate and volcanic minerals.

Biofortification using agronomic practices can be used to improve the nutritional quality of food crops. Three natural media amendments (dry vermicast, potassium (K)-humate and volcanic minerals) were assessed under greenhouse conditions to determine the effects on the chemical composition of kale (Brassica oleracea L. var. acephala 'Ripbor'). The results indicated that K-humate had low pH, while the volcanic minerals had high pH. Plants grown in the dry vermicast amended media had the highest levels of macronutrients and micronutrients except for zinc and iron. However, the glycolipid: phospholipid ratio was lower in kale plants cultivated in dry vermicast compared to plants cultivated in the volcanic minerals or K-humate. Conversely, plants cultivated in the dry vermicast had enhanced levels of polyunsaturated fatty acids. The omega-3 fatty acid content was significantly (P < 0.05) higher in plants cultivated in dry vermicast and potassium humate, while the omega-6 fatty acids were unaffected by media amendments. Dry vermicast was the most effective at increasing plant tissue oleic acid content. The total phenolic content and antioxidant capacity were highest in plants treated with K-humate, but lowest in the dry vermicast treated plants. In conclusion, dry vermicast proved to be the most effective in enhancing the phytochemical composition of kale 'Ripbor'. These results suggest dry vermicast could be a potential target natural media amendment for biofortifying kale plants during cultivation.