Homogeneous, heterogeneous and enzymatic catalysis for transesterification of high free fatty acid oil (waste cooking oil) to biodiesel: a review.

Simulated gastro-intestinal digestion is widely employed in many fields of food and nutritional sciences, as conducting human trials are often costly, resource intensive, and ethically disputable. As a consequence, in vitro alternatives that determine endpoints such as the bioaccessibility of nutrients and non-nutrients or the digestibility of macronutrients (e.g. lipids, proteins and carbohydrates) are used for screening and building new hypotheses. Various digestion models have been proposed, often impeding the possibility to compare results across research teams. For example, a large variety of enzymes from different sources such as of porcine, rabbit or human origin have been used, differing in their activity and characterization. Differences in pH, mineral type, ionic strength and digestion time, which alter enzyme activity and other phenomena, may also considerably alter results. Other parameters such as the presence of phospholipids, individual enzymes such as gastric lipase and digestive emulsifiers vs. their mixtures (e.g. pancreatin and bile salts), and the ratio of food bolus to digestive fluids, have also been discussed at length. In the present consensus paper, within the COST Infogest network, we propose a general standardised and practical static digestion method based on physiologically relevant conditions that can be applied for various endpoints, which may be amended to accommodate further specific requirements. A frameset of parameters including the oral, gastric and small intestinal digestion are outlined and their relevance discussed in relation to available in vivo data and enzymes. This consensus paper will give a detailed protocol and a line-by-line, guidance, recommendations and justifications but also limitation of the proposed model. This harmonised static, in vitro digestion method for food should aid the production of more comparable data in the future.

https://hal.archives-ouvertes.fr/hal-01209876/document

A standardised static in vitro digestion method suitable for food – an international consensus

Over the past 5 years growing demands for reducing fat content of fried foods have greatly stimulated the amount of research spent on the issue of fat uptake during deep-fat frying. The results of these efforts are summarized in this review. Most of the increased understanding of the mechanism of fat uptake has been brought about by improved imaging techniques. It turns out that fat uptake is basically determined by two mechanisms: the condensation effect and the capillary effect. Major reductions claimed in literature and patents are found for coating and batter formulations using various types of biopolymers.

Mechanism and reduction of fat uptake in deep-fat fried foods

Introduction to surface topography.- The areal field parameters.- The areal feature parameters.- Areal filtering methods.- Areal form removal.- Areal fractal methods.- Choosing the appropriate parameter.- Characterization of individual areal features.- Multi-scale signature of surface topography.- Correlation of areal surface texture parameters to solar cell efficiency.- Characterisation of cylinder liner honing textures for production control.- Characterization of the mechanical bond strength for copper on glass plating applications.- Inspection of laser structured cams and conrods.- Road surfaces.

Characterisation of Areal Surface Texture

Lipases are very versatile enzymes, and produced the attention of the several industrial processes. Lipase can be achieved from several sources, animal, vegetable, and microbiological. The uses of microbial lipase market is estimated to be USD 425.0 Million in 2018 and it is projected to reach USD 590.2 Million by 2023, growing at a CAGR of 6.8% from 2018. Microbial lipases (EC 3.1.1.3) catalyze the hydrolysis of long chain triglycerides. The microbial origins of lipase enzymes are logically dynamic and proficient also have an extensive range of industrial uses with the manufacturing of altered molecules. The unique lipase (triacylglycerol acyl hydrolase) enzymes catalyzed the hydrolysis, esterification and alcoholysis reactions. Immobilization has made the use of microbial lipases accomplish its best performance and hence suitable for several reactions and need to enhance aroma to the immobilization processes. Immobilized enzymes depend on the immobilization technique and the carrier type. The choice of the carrier concerns usually the biocompatibility, chemical and thermal stability, and insolubility under reaction conditions, capability of easy rejuvenation and reusability, as well as cost proficiency. Bacillus spp., Achromobacter spp., Alcaligenes spp., Arthrobacter spp., Pseudomonos spp., of bacteria and Penicillium spp., Fusarium spp., Aspergillus spp., of fungi are screened large scale for lipase production. Lipases as multipurpose biological catalyst has given a favorable vision in meeting the needs for several industries such as biodiesel, foods and drinks, leather, textile, detergents, pharmaceuticals and medicals. This review represents a discussion on microbial sources of lipases, immobilization methods increased productivity at market profitability and reduce logistical liability on the environment and user.

/pdf/microbial-lipases-and-their-industrial-applications-a-2irfn31kx3.pdf

Microbial lipases and their industrial applications: a comprehensive review

Comparison between atmospheric and vacuum frying of apple slices

https://repositorio.uchile.cl/bitstream/handle/2250/121021/Dueik_V.pdf?sequence=1

Vacuum frying reduces oil uptake and improves the quality parameters of carrot crisps

During the last decade much attention has been given to investigating oil absorption during frying. Several studies have suggested the key role of the dehydrated crust, which is thought to control the main mechanisms in oil absorption, that is drainage and capillary suction during post-frying cooling. To contribute to a better understanding of these mechanisms, we have used infrared microspectroscopy at the Synchrotron Radiation Source at Daresbury (UK) to monitor the oil distribution in fried potato cylinders. We report what we believe to be the first quantitative data on oil distribution within a fried product. Results show that the oil distribution within the crust reflects the anisotropic nature of the porous region in accordance with the proposed mechanism of oil absorption. Pendant ces dernieres decenies, une grande attention a ete donnee a l'etude de l'absorption d'huile pendant la friture. Pour une meilleure comprehension des mecanismes d'absorption de l'huile, cet article rapporte une etude sur l'utilisation de la microspectrometrie infrarouge a haute resolution spatiale pour suivre la penetration de l'huile dans des cylindres de pommes de terre pendant la friture. L'hypothese proposee est que le croute deshydratee joue un role tres important dans l'absorption de l'huile, de drainage et de succion capillaire pendant le refroidissement apres friture.

Oil Distribution in Fried Potatoes Monitored by Infrared Microspectroscopy

Summary Frying induces major structural changes in the surface of foods inﬂuencing oil uptake. Thiswork discusses the use of several di•erent methods of microscopy as well as techniques ofimage analysis to study frying at the microstructural level. Hot-stage video microscopy wasinstrumental in assessing geometrical changes in cells of potato tissue and in starch in realtime. The swelling of starches inside cells appeared to be retarded compared with that instarch suspensions. Confocal laser scanning microscopy (CLSM) permitted ‘optical’sectioning of the crust, revealing that oil was located in the interior in pockets orsurrounding intact cells. The manipulation of microscopy data by image processing is alsopresented.Keywords Confocal laser scanning microscopy, hot-stage microscopy, image analysis, oil-uptake. IntroductionFrying is an operation used world-wide to createunique ﬂavours and textures in foods. Deep-fat orimmersion frying is a complex process thatinvolves simultaneous heat and mass transfer,resulting in counterﬂow of water vapour (bubbles)and oil at the surface of the food, physico-chemical alterations of major food componentsand signiﬁcant microstructural changes (Singh,1995). In fact, desirable characteristics of mostfried foods are derived from the formation of acomposite structure: a dry, crisp and oily outerlayer or crust, and a moist cooked interior or core.The structure of the crust of fried potatoproducts is the result of several alterations, mostof which occur at the cellular and subcellular level.They take place in the outer cell layers of theproduct and the major changes include: physicaldamage owing to cutting (slicing), release ofcontents of broken cells, gelatinization of starchgranules, softening of cell walls, fast dehydrationof tissues and formation and release of vapourbubbles. Microstructural changes in the core aremuch milder and similar to those occurring duringthe cooking of potatoes, the major ones beinghydration and swelling of starch granules andsoftening of the middle lamellae.The importance of microstructural changesduring deep-fat frying has been recognized inmodelling heat and mass transport and unravel-ling their mechanisms. Three of ﬁve papers byleading scientists in the ﬁeld published in anoverview on the frying of foods (Moreira et al.,1995; Rao & Delaney, 1995; Singh, 1995) includedscanning electron microscopy (SEM) photomicro-graphs of fried products, suggesting the import-ance of microstructure. Similarly, Baumann& Escher (1995) recommended that ‘…explana-tions of some factors in the oil uptake still need tobe validated by structure analysis of the potatocrisp in relation to the location of oil depositionand to the mechanism of oil adhesion to thesurface’.Since the ﬁrst histological studies of deep-fatfried potatoes by Reeve & Neel (1960) evidencehas accumulated that, except for the outermostlayers damaged by cutting, the majority of theinner cells retain their individuality after fryingand contain in their interior dehydrated butgelatinized starch granules. The microstructuralaspect of the core tissue is similar to that of

Microstructural analysis of frying potatoes

One of the most important quality parameters of fried food is the amount of fat absorbed during the process, which undermines recent consumer trends toward healthier food and low-fat products. In order to obtain a product with a low fat content, it is essential to understand the mechanisms involved during the frying process, so that oil migration into the structure can be minimized. To get such an understanding, this chapter briefly describes the frying process from technological and scientific perspectives. First, it gives a general overview of the frying process and describes the most important quality attributes of fried food. Thereafter, it centers on key nutritional aspects, particularly on the effect of excessive oil consumption on human health, oil degradation, and toxic compounds generation in fried food. Finally, this chapter discusses the most important factors affecting oil absorption, oil absorption kinetics, and different strategies that may be adopted to decrease oil content.

Pedro Bouchon

Papers

Comparison between atmospheric and vacuum frying of apple slices

Vacuum frying reduces oil uptake and improves the quality parameters of carrot crisps

Oil Distribution in Fried Potatoes Monitored by Infrared Microspectroscopy

Microstructural analysis of frying potatoes

Understanding oil absorption during deep-fat frying.