Diacylglycerol production processes

During the hydrolysis of oils and fats by ordinary lipases, partial glycerides tend to accumulate and the rate of hydrolysis of the triacylglycerol decreases. This phenomenon has been exploited in producing diacylglycerols. 

Direct synthesis of diacylglycerols from fatty acids and glycerol was achieved by Hoq et al. (1984) on a hydrophobic membrane reactor, yielding 80-90% mixtures of di- and mono-acylglycerols. The product composition was dependent on the type of lipase used (Hoq et al., 1985). 

The method described by Jensen et al. (1978) uses a unique lipase from Geotrichum candidum. The specificity of this enzyme to oleic and linoleic acids regardless of their positions on the glycerol chain (Jensen and Pitas, 1976) indicates that these fatty acids could be preferentially produced from esters of these acids. Similarly diacylglycerols could be produced from triacylglycerol containing only one of these fatty acids. 

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Lo S K, Cheong LZ, Ariffin N, et al. 2007. Diacylglycerol and triacylglycerol as responses in a dual response surface-optimized process for diacylglycerol production by Upase-catalyzed esterification in packed-bed reactor. J Agric Food Chem 55 5595-5603. 

G-proteins are so called because they bind a guanosine nucleotide, either GTP or GDP. Their transduction mechanism involves the production of a second messenger such as 3 5 cAMP, 3 5 cyclic GMP (cGMP) or IP3 and diacylglycerol (DAG), derived from AMP, GMP and phosphatidyl inositol-3,5bisphosphate respectively (Figure 4.15). It is the second messenger that initiates the downstream amplification process phase of transduction. 

In many food products and even some processing operations, it is important to be able to control lipid crystallization to obtain the desired number, size distribution, polymorph, and dispersion of the crystaHine phase. In most foods, it is crystallization of triacylglycerols (TAG) that is most important, although, at times, crystallization of other lipids (i.e., monoacylglycerols, diacylglycerols, phospholipids, etc.) may also be important to product quality. 

It is now generally accepted that both of the products of phosphatidylinositol 4,5-bisphosphate hydrolysis can function as intracellular second messengers. 1,2-Diacylglycerol can affect a variety of intracellular processes by activation of protein kinase C [ 148, 229, 230]. Inositol 1,4,5-trisphosphate, on the other hand, has been shown to release calcium ions from non-mitochondrial stores in a number of peripheral tissues and may thus be the link between the receptor and the intracellular calcium store in many pharmacological responses [231-233]. Furthermore, it remains a possibility that inositol phospholipid hydrolysis may also have a r61e in calcium gating [221,234]. If inositol phospholipid metabolism is closely coupled to receptor-mediated calcium mobilization, then this response may be a more general consequence of H,-receptor stimulation than other H,-responses. 

The opposite process takes place during the germination (Section 11.5.2), so that lipids of germinating seeds may also contain mono- and diacylglycerols as TAG degradation products. 

The PLC-Dependent Mechanisms. The PLC-dependent mechanisms, in contrast to the PKA-dependent signaling system, are important regulators of basal PG production. PG synthesis is associated with activation of PLC and subsequent production of diacylglycerol, inositol-1,4,5-triphosphate, release of Ca ", and Ca -induced activation of PKC (1). Stimulation of PKC by phorbol 12,13-dibutyrate activates PGF secretion by bovine endometrial cells (3). In hamster ovarian cells and rabbit amnion cells, OT activated production of both PGE and PLC, which suggests that the PLC-dependent signaling pathway not only controls basal PG secretion, but also mediates the effect of OT on this process (9). 

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