mechanism of rancidity

Introduction

Rancidity is a significant issue in food science, leading to undesirable flavors and odors in food products. It primarily results from the oxidative degradation of lipids, which can be influenced by various factors including the presence of unsaturated fatty acids, exposure to light, and the physical properties of food dispersions.

Key Insights

Oxidative Mechanisms:
- Rancidity is often initiated by the autoxidation of lipids, particularly unsaturated fatty acids like oleic acid, leading to the formation of aldehydes and other compounds that contribute to off-flavors and odors .
- The presence of atmospheric oxygen plays a crucial role in the oxidative deterioration of lipids, resulting in a complex series of reactions that produce both volatile and non-volatile compounds.
Role of Physical Properties:
- The physical properties of food dispersions, such as the oil-water interface, significantly impact lipid oxidation pathways. Emulsifiers and the location of prooxidative transition metals can influence the rate and extent of lipid oxidation.
Photochemical Influences:
- Light exposure can accelerate rancidity through photochemical reactions. In vegetable oils, disrupted photosynthesis and the photosensitizing action of pigments like chlorophyll can lead to the formation of unstable peroxides, which further react with lipids to produce rancid compounds.
Enzymatic Factors:
- Enzymes such as lipases can also contribute to rancidity. For instance, the addition of pancreatic lipase to condensed milk has been shown to produce rancid flavors, increase acidity, and viscosity, mimicking the effects of raw milk.
Preventive Measures:
- Understanding the mechanisms of lipid oxidation has led to the development of strategies to slow down rancidity. These include creating lipid structures that minimize interactions with prooxidants and oxygen, and increasing antioxidant concentrations at the site of oxidation.
- Specific processing conditions, such as heating milk to certain temperatures, can destroy lipolytic enzymes and prevent rancidity in dairy products.

Conclusion

Rancidity in food products is primarily driven by oxidative and enzymatic mechanisms, influenced by factors such as the presence of unsaturated fatty acids, exposure to light, and the physical properties of food dispersions. Preventive measures, including the use of antioxidants and specific processing conditions, can help mitigate the development of rancidity. Understanding these mechanisms is crucial for developing effective strategies to maintain food quality and extend shelf life.

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Mechanism of rancidity

Summary

Introduction

Key Insights

Conclusion

Sources and full results

Possible mechanisms of autoxidative rancidity

Autoxidative rancidity results from a complex series of reactions involving free radicals and oleic monohydroperoxides, yielding a wide variety of offensive taste and odor products.

Mechanisms of lipid oxidation in food dispersions

Understanding the mechanisms of lipid oxidation in food dispersions can lead to novel antioxidant technologies that slow down rancidity development by decreasing interaction between lipids and prooxidants and increasing antioxidant concentrations.

Sweetened Condensed Milk: V. Rancidity*,1

Rancidity in condensed milk is caused by pancreatic lipase, unheated milk, raw milk, and certain metals, not bacteria.

Photochemical studies of rancidity: The mechanism of rancidification

Disrupted photosynthesis in vegetable oils and photosensitizing action of haemoglobin or animal pigments in animal fats cause rancidity by liberating hydrogen peroxide, forming glyceride peroxide, and splitting into aldehyde compounds.

Oxidative rancidity in foods and food quality

Oxidative rancidity in foods is caused by lipid oxidation, leading to off-flavours and affecting food quality, with various analytical methods and recommendations for preventing or retarding lipid oxidation.

Rancidity of fermented mash of mechanical yellow rice wine and its prevention measures

The causes of rancidity in mechanical yellow rice wine production include yeast culture differences, raw wheat koji quality, acidity influence of rice milk, rice and steamed rice quality, inaccurate ratio of ingredients, higher or lower temperature, inferior sanitation, and unclean raw materials.

OBSERVATIONS ON THE PIPELINE MILKER OPERATION AND ITS EFFECT ON RANCIDITY

The type of pipeline milking system and operating conditions are key factors in reducing rancidity in bulk tank milk, while advanced lactation stage and dry feed feeding conditions may increase the risk.

Rancidity in Lean Fish Muscle.: IV. Effect of Sodium Chloride and Other Salts

Sodium chloride accelerates rancidity in cod muscle at 0 C, with other metal salts also having similar pro-oxidant effects, and their antioxidant effects can be beneficial in preventing copper-induced rancidity.

Effects of rice bran rancidity on the oxidation and structural characteristics of rice bran protein

Rice bran rancidity leads to oxidation of rice bran protein, resulting in loss of secondary structure and formation of aggregates and cross-links.

Stability and rancidity

The active oxygen method, Schaal oven test, thiobarbituric acid test, carbonyl test, and oxidation test are commonly used methods for assessing the stability or rancidity of fats and fat-based foods.

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