Abstract
ABSTRACTThree palm mid-fraction (PMF) groups produced from different fractionation paths were analyzed in terms of the fat, triacylglycerol and sn-2 fatty acid compositions, thermal properties (melting and crystallization behaviors, and solid fat contents (SFCs)), micronutrient levels and oxidative stability indexes (OSIs) to achieve their sufficient utilization. PMF-A (iodine value (IV), 48.4 g/100 g) fractionated from palm olein contained 43.8% 1,3-dipalmitoyl-2-oleoyl-glycerol (POP) and 16.7% 1-palmitoyl-2,3-dioleoyl-glycerol, showing soften properties (slip melting point (SMP), 27.6°C; SFC at 30°C, 2.2%) at hot weather. PMF-B (IV, 42.3 g/100g) obtained from palm stearin showed similar fat and triacylglycerol compositions as PMF-A, but the high 1,2,3-tripalmitoyl-glycerol level (6.2%) improves its thermal behaviors (SMP, 34.9°C; SFC at 30°C, 13.8%). The SFC profiles of PMF-A and PMF-B were comparable to those found in frozen and puff margarine shortenings. Furthermore, both of the PMF groups exhibited excellent OSIs (13.2 and 11.2 h, respectively) because of their high micronutrient levels (especially γ-tocopherol and campesterol). In general, γ-tocopherol and campesterol contribute to preventing lipids from oxidation under frying conditions. Therefore, PMF-A and PMF-B are recommended for manufacturing margarine shortenings and frying fasts. PMF-C (IV, 33.0 g/100g) produced from the additional fractionation of PMF-A or PMF-B contained the highest POP percentage (67.1%) and showed heat-resistant property (SMP, 31.8°C; SFC at 30°C, 22.4%). Its steep SFC profile was superior to that of cocoa butter, suggesting the fat is preferred in producing hard chocolate fats.
Highlights
Palm mid-fractions (PMFs) are produced by multi-stage fractionation from palm oil and has been widely popular in the formulation of various food ingredients due to their high yields, unique physicochemical properties and nutritional values.[1]
They fell within the ranges of 42.0–48.0 g 100g−1 for soft PMF, 40.0–42.0 g 100 g−1 for soft stearin and 32.0–36.0 g 100g−1 for hard PMF respectively[5], indicating the studied PMF samples are representative
Significant differences (p < 0.05) of triacylglycerol and diacylglycerol percentages were found between PMF-C and PMF-A/PMF-B, while the iodine value (IV) (g/100g) Fat composition (%)
Summary
Palm mid-fractions (PMFs) are produced by multi-stage fractionation from palm oil and has been widely popular in the formulation of various food ingredients (e.g., chocolate/confectionery fats, icings, shortenings, margarines and frying fats) due to their high yields, unique physicochemical properties and nutritional values.[1] The annual output of PMFs amounts to 14–17 million tons calculated based on the production quantity of palm oil and related fractionation yields[2], which meets the demands for processed fat-containing food. PMFs are strongly suggested to be used as chocolate fats, and the potential demand of cocoa butter equivalents (CBEs, one of the high-quality chocolate fats) is estimated to be only 0.025–0.050 million tons annually according to the European Directive 2000/36/EC.[1,3] In contrast, most of other chocolate fat resources, i.e., illipe butter, sal fat, and shea butter, are usually difficult to obtain because of their intermittent availabilities and low yields.[4] In this regard, PMFs are the most ideal ingredients in the confectionery manufacture. Industrial PMFs are divided into three groups as shown in Fig. 1: PMF-A, known as soft PMF, is generally obtained from dry fractionation of the palm olein or PMF-B as the following process: fast cooling to 16°C and keeping at this temperature for 1 h, follow by fast or slow cooling to 12–13°C and holding for 5–7 h[1,5,6]; PMF-B, named soft stearin or low melting stearin, is generally fractionated from the palm stearin or PMF-A using acetone in a ratio of 1:4–8 (w:v) at 17–25°C for 8–48 h[5,7]; and PMF-C, called hard PMF or 1,3-dipalmitoyl-2-oleoylglycerol (POP)-rich fat, is produced from the additional fractionation of PMF-A or PMF-B using acetone in a ratio of 1:10 (w:v) at 4°C for 24 h.[5,8]
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