Identification of major triglycerides causing the clouding of palm olein

Self Cite

The enzymatic transesterification of palm olein was conducted in a low-moisture medium with nonspecific and 1,3-specific lipases from microbial sources. The enzymes were first immobilized on Celite, ]yophilized for 4 h and then added to a reaction medium that consisted of 10% (wt/vo[) palm olein in water-saturated hexane. The catalytic performance of the enzymes was evaluated by determining the changes in triglyceride (TG) composition and concentrations by reverse-phase highperformance liquid chromatography (HPLC) and the formation of free fatty acids by titration. Studies with lipase from Candida rugosa showed that the degree of hydrolysis was reduced by drying the immobilized preparation and that the best drying time was 4 h. In all cases, the transesterification process resulted in the formation of PPP, a TG initially undetected in the oil, and increases in the concentrations of OOO (1.3-2.1-fold), OOL (1.7-4.5-fold), and OLL (1.7-4.3-fold), where P, O, and L are palmitic, oleic, and linoleic acids, respectively. SOS (where S is stearic acid), another TG not detected in the oil, was synthesized by Rhizomucor miehei and Pseudomonas lipases, with the latter producing more of this TG. There was a corresponding decrease in the concentrations of POP, PLP, POO, and POL. PPP concentration ranged from 1.9% (w/w) for Mucorjavanicus [ipase to 6.2% (w/w) for Pseudomonas lipase after 24 h. The greatest degree and fastest rate of change were caused by Pseudomonas lipase, followed by the enzymes from R. miehei and Aspergillus niger. The effects of transesterification and hydrolysis of palm olein by the various lipases resulted in changes in the overall degree of saturation of the triglyceride components. There seems to be no clear correlation between the enzyme positional specificity and the products formed. Possible mechanisms for the formation of PPP, OOL, OLL, OOO, and SOS are discussed. JAOCS 72, 633-639 (1995).

Section: Methodsmentioning

confidence: 99%

Enzymatic transesterification of palm olein with nonspecific and 1,3‐specific lipases

Ghazali

Hamidah

Man

1995

Self Cite

“…In the case of solid fat-based food materials such as chocolates [1][2][3], margarine/fat spreads [4], and butter [5], the crystallization processes of fats greatly affect their melting properties, textures, rheology, and storage stability. Furthermore, in liquid oil-based products such as cooking oils [6,7], mayonnaise, and dressings [8,9], the crystallization of small amounts of high-melting fractions affects the product quality. For example, the crystallization of high-melting components in cooking oils at chilled temperatures (often referred to as precipitation) causes phenomena undesired for real applications.…”

Section: Introductionmentioning

confidence: 99%

“…For example, the crystallization of high-melting components in cooking oils at chilled temperatures (often referred to as precipitation) causes phenomena undesired for real applications. Therefore, preventing precipitation during storage is essential for cooking oils derived from vegetable oils such as palm oil fractions [6,7]. Furthermore, the destabilization of emulsified states in mayonnaise at freezing temperatures is caused by fat crystallization and ice crystal formation [8].…”

Section: Introductionmentioning

confidence: 99%

Crystallization Behavior of Diacylglycerol‐Rich Oils Produced from Rapeseed Oil

Saitou

Mitsui

Shimizu

et al. 2012

We examined the crystallization behavior of high-melting fractions in liquid oil containing high concentrations of diacylglycerols (DAG [80%) (hereafter referred to as DAG-rich oil). By differential scanning calorimetry and optical microscopy at moderate cooling rates, crystallization in the DAG-rich oil was detected at around 6°C. It was found that the crystallization extent increased with decreasing temperatures of crystallization below 0°C. A gas chromatographic analysis was performed on the crystallized fractions, which were separated by filtration at different periods of isothermal crystallization at 3°C. The results indicated that at earlier crystallization periods, the concentrations of 1,3-disaturated DAG such as palmitic and stearic acid moieties (15 min) and 1,3-saturated-unsaturated mixed-acid DAG including oleic acid, palmitic, and stearic acid moieties (15 min-3 h) were predominant. However, the concentrations of 1,3-diunsaturated DAG including oleic acid moiety increased after a crystallization period of 6 h. To clarify the sequential crystallization process of DAG, we examined the binary mixing behavior of principal DAG components occurring in the rapeseed-based DAG-rich oil. It was evident that 1,3-disaturated DAG, 1,3-saturated-unsaturated mixedacid DAG, and 1,3-diunsaturated DAG exhibited immiscible behavior. From these data, basic information on the precipitation processes in DAG-rich oils at chilled temperatures was obtained.

“…In addition, it also contains up to 5% diglycerides (1). Tripalmitin (PPP), present in significant quantities in palm oil, has long been associated with the unwanted formation of crystals and subsequent clouding of palm olein (2,3). In foodprocessing industries, palm oil blends are frequently mixed with other ingredients and partially crystallized to give a plasticized fat.…”

mentioning

confidence: 99%

Measurement of particle size distribution of tripalmitin crystals in a model solution using a laser diffraction method

Fitzgerald

Barnes

Smart

et al. 2001

The form and size distribution of tripalmitin (PPP) crystals formed by quenching a solution in a batch crystallizer have been studied using scanning electron microscopy and a laser diffraction technique. Although the accuracy of the laser technique for particle sizing was affected by the nonsphericity of the crystals, the technique proved to be effective and very reproducible. Crystals recovered by filtration and sonication for laser sizing exhibited markedly different particle size distributions (PSD) and shapes compared to those prepared using another standard route, namely, suspension in butanol and centrifugation. Solutions of 2-10 wt% PPP in a paraffin solvent were crystallized at 25-40°C and displayed two ranges of behavior: (i) rapid growth under strongly supersaturated conditions, yielding narrow PSD of plate and needle-like crystals; and (ii) slow growth in the metastable regime, yielding spherulitic aggregates of platelets that broke down under sonication during preparation for laser sizing. Suspension in alcohol followed by centrifugation yielded aggregates that did not break down under sonication, indicating that the sample preparation route affected the result of the analysis.The crystallization behaviors of palm oil and palm olein, the liquid fraction of palm oil, have been studied at length. Palm oil is a complex natural product, composed of more than 12 triglycerides that make up as much as 94% by weight of the oil. In addition, it also contains up to 5% diglycerides (1). Tripalmitin (PPP), present in significant quantities in palm oil, has long been associated with the unwanted formation of crystals and subsequent clouding of palm olein (2,3). In foodprocessing industries, palm oil blends are frequently mixed with other ingredients and partially crystallized to give a plasticized fat. However, during subsequent transport of the crystallized oil blend, deposition of PPP and other fats can occur onto the wall of delivery pipelines, a phenomenon known as "coring." Depositions of this type in process equipment can lead to increased maintenance, cleaning, and fuel costs (4) and also to more severe concerns related to hygiene, which are of prime importance in food processing (5). Analogous situations exist in the oil industry, where the formation of wax can be a major problem in oil well tubing and submarine pipelines (6), and models have been developed to predict and circumvent the buildup of unwanted deposits (7).The quality of plasticized fat is related both to the extent of crystallization and the size of crystals present in the suspension. In the food fat coring scenario, particle size distributions (PSD) are particularly important because the mode of particle transport to the wall and subsequent adhesion are strongly related to particle size and shape. Information on particle size and shape is required to identify and model the mechanisms involved in deposition (e.g., Ref. 8). Previous studies have focused on measurement of PPP crystal size by optical methods (9). Although laser diffraction has b...