Characterization and application of a microemulsion as model system for lipophilic phytochemicals in high‐pressure processing

Abstract

AbstractHigh‐pressure processing (HPP) is considered as gentle preservation technique for especially heat‐sensitive food ingredients. So far, the focus has been on the fact that it is called a nonthermal process and high pressure can affect bioavailability, but it is questionable whether the high pressure affects the ingredients themselves. By using an o/w‐microemulsion (ME) as a model system, it was possible to investigate the influence of pressure, especially on lipophilic compounds (e.g., carotenoids and vitamin E), without the complexity of a food matrix. The ME consisted of Capryol® TM 90, Tween® 80 or 20, Transcutol® HP and distilled water. Lipophilic and hydrophilic compounds were introduced to the oil phase and to the aqueous phase, respectively. Storage experiments confirmed the applicability for β‐carotene and α‐tocopherol. HPP of MEs, performed for 10 min at room temperature (RT) and up to 600 MPa, resulted in pressure stability of β‐carotene (exceptional at 400 MPa; −11%) and α‐tocopherol. Multicomponent ME showed that both had a positive effect on the stability of chlorophyll a/b during HPP. An ME environment was used to facilitate co‐oxidation of β‐carotene via lipoxygenase (LOX) from an Edamame‐based crude enzyme extract and lyophilized LOX‐1 from soybeans during storage (RT and 4°C, dark conditions) and HPP treatment. A loss of β‐carotene occurred after addition of linoleic acid, whereas effects of added α‐tocopherol could be related to β‐carotene protection. Overall, the introduced ME for studying HPP effects on lipophilic food ingredients showed promising results as versatile model system for future investigations regarding interactions of phytochemicals.