The purpose of this study was to extract phenolics from lemon balm followed by microencapsulation with spray drying. The optimum extraction conditions were 100°C for the temperature and 120 min for the time with TPC of 6,365 mg GAE/100 g and ABTS radical scavenging activity of 9,196 mg TEAC/100 g. Lemon balm extracts were spray dried using three different air inlet temperatures (130°C, 165°C, and 200°C) of which 165°C was provided better scores than the other points in terms of microencapsulation yield (65.9%), microencapsulation efficiency (99.4%), dry matter (98.3%), and water activity (0.160). The inlet air temperatures had an insignificant (p > .05) effect on the antioxidant capacity of the microcapsules. Phenolic acids in lemon balm were slightly affected by the extraction and spray drying conditions. However, extraction followed by spray drying resulted in significant loss in the amount of volatiles such as geranial, neral, citronellal, and caryophyllene.
Practical applications
Hot water extracts of the medicinal and aromatic plants are consumed as herbal tea across the world and their biological activity varies depending on the extraction conditions. Furthermore, bioactive compounds are sensitive to environmental conditions when the compounds dissolved in water. The conditions necessary for the effective extraction of bioactive compounds are specific to the target plant and it is a problem for the consumer. Optimization of extraction conditions of lemon balm phenolics could provide useful information for the consumer and food industry. The production of phenolic microcapsules (instant soluble tea) from lemon balm could facilitate herbal tea preparation and reduce the preparation time.
Summary
In this study, the extraction of bioactive compounds from lemon peel, a by‐product of the food industry, was investigated using pressurised hot water extraction (PHWE) at different extraction temperatures (40–200 °C) and times (5–30 min) under 10.34 MPa pressure. The selectivity of the PHWE process on eriocitrin and hesperidin extraction was also tested. The highest total phenolic content (TPC) (59.57 mg gallic acid equivalents g−1), total flavonoid content (TFC) (8.22 mg catechin equivalents g−1) and antioxidant capacity by DPPH (42.59 mg Trolox equivalents (TE) g−1) were obtained at 160 °C for 30 min. The maximum eriocitrin (30.41 mg g−1) and hesperidin (25.90 mg g−1) contents were achieved at 160 °C for 5 min with a 5‐hydroxymethyl furfural content of 0.07 mg g−1. PHWE provided better results for individual compounds and antioxidant capacities than conventional extraction. The results indicated the potentiality of PHWE in the selective extraction of eriocitrin and hesperidin from lemon peel by controlling the extraction temperature and time.
In this Research Communication we describe the optimisation of spray drying conditions in the production of microencapsulated cream powder. Oil-in-water emulsions were prepared using maltodextrin (18 DE) and sodium caseinate as wall materials (with the total wall material per total solid content ratio of 30%) and then converted into powder by spray drying. Response surface methodology was used to optimise the factors of spray drying system i.e. inlet drying temperature, feed flow rate, and aspiration rate, where the levels were in the range of 150–190°C, 9–30 ml/min, and 50–100%, respectively. Our objective was to perform spray drying with the highest drying yield and to obtain a microencapsulated cream powder with the highest bulk density, the shortest wetting time, and the lowest surface fat content. The calculated and validated optimum conditions for the spray drying process were found to be 162.8°C for inlet drying temperature, 11.51 ml/min for feed flow rate, and 72.8% for aspiration rate. At these optimum conditions, drying yield, bulk density, wettability, and surface fat content values were 36.37%, 269.9 kg/m3, 115.2 s and 26.2%, respectively.
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