Abstract
Currently, flaxseed oil is used as an important functional food constituent owing to its large content of omega-3 fatty acids. However, flaxseed oil does not contain carotenoids that could enhance the oxidative stability of the oil. In this study, carotenoids extracted from sea buckthorn pomace were used to enrich cold-pressed flaxseed oil via an ultrasound-assisted extraction technique (UAE). The process parameters were optimized through Box-Behnken design to maximize the carotenoid content in the flaxseed oil. The results obtained by statistical analysis indicated that the yield of 14.02 mg/L of carotenoid content was found in the enriched flaxseed oil at 75.6 min, feed to oil ratio of 19.9 (wt. basis), and amplitude 80.81%. Further, UAE at optimum process parameters was compared with the conventional extraction (CE) method, and it was found that UAE had ~ 49 wt% of higher carotenoid content relative to CE. The physicochemical properties of the enriched flaxseed oil were determined to evaluate the effects of carotenoid enrichment in the flaxseed oil. Based on the outcomes of the present investigation, enriched flaxseed oil could be the potential source for the pharmaceuticals and nutraceuticals industry.
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Key Points
The enrichment of foods/edible oil with compounds capable of acting as antioxidants either to extend their shelf life or to incorporate compounds with healthy properties has become standard practice in recent years. Currently, the enrichment of edible oils is carried out by three different techniques; the first process involves the extraction of plant biomass through the conventional solvent extraction process and adding it to edible oils in recommended proportions.
In the current study, sea buckthorn pomace is used for the enrichment of flaxseed oil. Sea buckthorn (Hippophae rhamnoides L.) is a native plant of cold temperature regions of Europe and Asia. Worldwide, various parts of sea buckthorn plants, berries, juice, pomace, and seeds are used in traditional medicine preparation, food, and the cosmetic industry. Due to the high content of carotenoids (determined at 24.56 ± 1.55 mg/100 g and 16.67 mg/100 g by spectrophotometric and HPLC methods, respectively) in sea buckthorn pomace, it is used in the extraction of bioactive compounds for value addition of edible oils.
The main objective of this study is to increase the nutritive value of flaxseed oil by using sea buckthorn pomace. Process parameters (time, feed to oil ratio, and ultrasonic power) are optimized through Box-Behnken design to maximize the carotenoids content in the enriched flaxseed oil. Further, the physicochemical analysis of the flaxseed oil before and after enrichment is carried out to determine the quality and oxidative stability of the flaxseed oils. In addition, UAE is compared with conventional extraction (CE) at similar process parameters for three consecutive cycles to determine the total carotenoids content present in sea buckthorn pomace and extraction efficiency of the UAE technique.
It is found that UAE significantly enhanced the extraction of carotenoids in less time compared to CE. From the assessment of design expert results, optimized conditions are found to be time – 75.5 min, feed ratio – 19.9, and amplitude – 80.8%; at these conditions, the yield of carotenoids is 14.02 mg/L. The studies indicated that the UAE significantly decreased the extraction time. Carotenoid of enriched flaxseed oil is found to be 14.02 mg/L by spectrophotometer analysis, likewise, β-carotene content is found to be 11.26 mg/L.
The results of this study determined the application of sea buckthorn pomace for the enrichment of edible oils. UAE technique is found to be an effective method for extraction and direct enrichment of oils. It improved the nutritional value of edible oil, eliminating the use of hazardous solvents in the process. All the parameters of enriched flaxseed oil indicate the improvement of stability and quality of flaxseed oil. β-carotene enriched flaxseed oil can be used in the nutraceutical and pharmaceutical industry as a dietary supplement. It can also be used in salad dressing oil, taste enhancer instead of butter or margarine in the food industry.