There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

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.

/pdf/a-standardised-static-in-vitro-digestion-method-suitable-for-tvm9kgy0s3.pdf

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

The brain and nervous system are prone to oxidative stress, and are inadequately equipped with antioxidant defense systems to prevent 'ongoing' oxidative damage, let alone the extra oxidative damage imposed by the neurodegenerative diseases. Indeed, increased oxidative damage, mitochondrial dysfunction, accumulation of oxidized aggregated proteins, inflammation, and defects in protein clearance constitute complex intertwined pathologies that conspire to kill neurons. After a long lag period, therapeutic and other interventions based on a knowledge of redox biology are on the horizon for at least some of the neurodegenerative diseases.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1471-4159.2006.03907.x

Oxidative stress and neurodegeneration: where are we now?

Effects of fatty acids on meat quality: a review

Free radicals, antioxidants, and nutrition.

The official International Dairy Federation method for determination of the peroxide value of anhydrous milk fat was extended to poultry, meat, fish, and vegetable oils. The ferrous oxidation-xylenol orange method for determination of peroxide values of liposomes and lipoproteins was modified to make it simpler and more rapid. These 2 spectrophotometric methods were used successfully to determine the peroxide values of beef, chicken, butter, fish, and vegetable products. The results in most cases were consistent with those obtained by using the AOAC Official Method. The spectrophotometric methods have an assay time of less than 10 min, require < or = 0.3 g fat, and are capable of determining peroxide values as low as 0.1 mequiv/kg of sample.

Rapid, sensitive, iron-based spectrophotometric methods for determination of peroxide values of food lipids


The susceptibility of lipids to oxidation is a major cause of quality deterioration in food emulsions. The reaction mechanism and factors that influence oxidation are appreciably different for emulsified lipids than for bulk lipids. This article reviews the current understanding of the lipid oxidation mechanism in oil-in-water emulsions. It also discusses the major factors that influence the rate of lipid oxidation in emulsions, such as antioxidants, chelating agents, ingredient purity, ingredient partitioning, interfacial characteristics, droplet characteristics, and ingredient interactions. This knowledge is then used to define effective strategies for controlling lipid oxidation in food emulsions.

Lipid Oxidation in Oil-in-Water Emulsions: Impact of Molecular Environment on Chemical Reactions in Heterogeneous Food Systems

Iron was released from ferritin by both cysteine and ascorbate at the pH found in muscle foods (5.5-6.9). The rate of iron release from ferritin was influenced by temperature and ferritin and reducing agent concentrations. Storing beef muscle at 4 degrees C for 11 days resulted in a decrease in the concentration of ferritin antibody precipitable iron, suggesting that iron is released from ferritin in situ. Physiological concentrations of ferritin catalyzed lipid oxidation in vitro, and heating ferritin increased the rate of lipid oxidation. These data suggest that ferritin could be involved in the development of off-flavors in both cooked and uncooked muscle foods.

Role of ferritin as a lipid oxidation catalyst in muscle food

Proteins can inhibit lipid oxidation by biologically designed mechanisms (e.g. antioxidant enzymes and iron-binding proteins) or by nonspecific mechanisms. Both of these types of antioxidative proteins contribute to the endogenous antioxidant capacity of foods. Proteins also have excellent potential as antioxidant additives in foods because they can inhibit lipid oxidation through multiple pathways including inactivation of reactive oxygen species, scavenging free radicals, chelation of prooxidative transition metals, reduction of hydroperoxides, and alteration of the physical properties of food systems. A protein's overall antioxidant activity can be increased by disruption of its tertiary structure to increase the solvent accessibility of amino acid residues that can scavenge free radicals and chelate prooxidative metals. The production of peptides through hydrolytic reactions seems to be the most promising technique to form proteinaceous antioxidants since peptides have substantially higher antioxidant activity than intact proteins. While proteins and peptides have excellent potential as food antioxidants, issues such as allergenicity and bitter off-flavors as well as their ability to alter food texture and color need to be addressed.

Antioxidant Activity of Proteins and Peptides

There is a pressing need for edible delivery systems to encapsulate, protect, and release bioactive lipids within the food, medical, and pharmaceutical industries. The fact that these delivery systems must be edible puts constraints on the type of ingredients and processing operations that can be used to create them. Emulsion technology is particularly suited for the design and fabrication of delivery systems for encapsulating bioactive lipids. This review provides a brief overview of the major bioactive lipids that need to be delivered within the food industry (for example, ω-3 fatty acids, carotenoids, and phytosterols), highlighting the main challenges to their current incorporation into foods. We then provide an overview of a number of emulsion-based technologies that could be used as edible delivery systems by the food and other industries, including conventional emulsions, multiple emulsions, multilayer emulsions, solid lipid particles, and filled hydrogel particles. Each of these delivery systems could be produced from food-grade (GRAS) ingredients (for example, lipids, proteins, polysaccharides, surfactants, and minerals) using simple processing operations (for example, mixing, homogenizing, and thermal processing). For each type of delivery system, we describe its structure, preparation, advantages, limitations, and potential applications. This knowledge can be used to facilitate the selection of the most appropriate emulsion-based delivery system for specific applications.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1750-3841.2007.00507.x

Eric A. Decker

Papers

Rapid, sensitive, iron-based spectrophotometric methods for determination of peroxide values of food lipids

Lipid Oxidation in Oil-in-Water Emulsions: Impact of Molecular Environment on Chemical Reactions in Heterogeneous Food Systems

Role of ferritin as a lipid oxidation catalyst in muscle food

Antioxidant Activity of Proteins and Peptides

Emulsion-based delivery systems for lipophilic bioactive components.