Abstract
The amplified production of fruit as well as burgeoning demand for plant-made food products have resulted in a sharp increase of waste. Currently, millions of tons of by-products are either being discarded or utilized rather ineffectively. However, these by-products may be processed and further incorporated as functional ingredients in making high-value food products with many physiological and biochemical effects. The chemical analysis of pomace oils using gas chromatography-mass spectrometry (GC/MS) and reversed-phase-liquid chromatography coupled with fluorescence detector (RP-HPLC/FLD) systems led to the identification and quantification of 56 individual lipophilic compounds including unsaturated, polyunsaturated and saturated fatty acids, as well as phytosterols and four homologs of tocopherol. The oils recovered from by-products of Malus spp. (particularly cv. “Ola”) are rich in fatty acids such as linolenic (57.8%), α-linolenic (54.3%), and oleic (25.5%). The concentration of total tocopherols varied among the Malus species and dessert apples investigated, representing the range of 16.8–30.9 mg mL−1. The highest content of total tocopherols was found in M. Bernu prieks, followed by M. cv. “Ola”, and M. × Soulardii pomace oils. A significantly higher amount of δ-tocopherol was established in the oil of M. Bernu prieks, indicating that this species could be utilized as a natural and cheap source of bioactive molecules. β-Sitosterol was the prevalent compound determined in all tested pomace oils with a percentage distribution of 10.3–94.5%. The main triterpene identified in the oils was lupeol, which varied in the range of 0.1–66.3%. A targeted utilization of apple pomace would facilitate management of tons of by-products and benefit the environment and industry.
Highlights
IntroductionDomesticated apple (Malus × domestica Borkh.) is one of the most important fruit crops worldwide
Domesticated apple (Malus × domestica Borkh.) is one of the most important fruit crops worldwide.According to FAOSTAT (2018) [1], the world production of apple in the last five decades has increasedPlants 2018, 7, 90; doi:10.3390/plants7040090 www.mdpi.com/journal/plantsPlants 2018, 7, 90 by 424% from 17.0 million tons in 1961 to 89.3 million tons in 2016
The results of this study suggest that the crab apple pomace oils of Malus spp., especially M
Summary
Domesticated apple (Malus × domestica Borkh.) is one of the most important fruit crops worldwide. In large-scale apple juice production, 75% of the apple are utilized for juice, while the remaining 25% are discarded as waste or utilized rather inefficiently [5] These by-products may be processed and further incorporated as ingredients in making high-value functional food products (cereal bars, cookies, muffins, bread and fermented milk products) with many physiological and biochemical effects [6]. Known as wild apples, belong to the genus Malus (Rosaceae family) and are currently used for ornamental purposes, and are one of the most important source of seeds with an increased concentration of all four homologs of tocopherol (α, β, γ and δ) [9], and hydrophilic antioxidant substances for the food and cosmetic industries [10]. The main objective of this study, analysis of the lipophilic constituents from the pomace of Malus crab apple, reflects the growing interest in finding new approaches for the recovery of by-products generated during fruit processing
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