The reaction of ninhydrin with primary amino groups to form the purple dye now called Ruhemann's purple (RP) was discovered by Siegfried Ruhemann in 1910. In addition, imines such as pipecolic acid and proline, the guanidino group of arginine, the amide groups of asparagine, the indole ring of tryptophan, the sulfhydryl group of cysteine, amino groups of cytosine and guanine, and cyanide ions also react with ninhydrin to form various chromophores of analytical interest. Since its discovery, extensive efforts have been made to apply manual and automated ninhydrin reactions as well as ninhydrin spray reagents to the detection, isolation, and analysis of numerous compounds of interest across a broad spectrum of disciplines. These include agricultural, biochemical, clinical, environmental, food, forensic, histochemical, microbiological, medical, nutritional, plant, and protein sciences. This reaction is unique among chromogenic reactions in that at pH 5.5 it results in the formation of the same soluble chromophore by all primary amines which react, be they amines, amino acids, peptides, proteins, and even ammonia. Because the chromophore is not chemically bound to the protein or other insoluble material, it is not lost when the insoluble substrate is removed by centrifugation or filtration after the reaction is completed. The visible color of the chromophore is distinctive and is generally not affected by the yellow colors present in many food, plant, and tissue extracts. Adaptations of the classical ninhydrin reaction to specialized needs in analytical chemistry and biochemistry include the use of acid, alkaline, and fluorogenic ninhydrin reagents. To cross-fertilize information among several disciplines wherein an interest in the ninhydrin reaction has developed, and to enhance its utility, this review attempts to integrate and correlate the widely scattered literature on ninhydrin reactions of a variety of structurally different compounds. Specifically covered are the following aspects: historical perspective, chemistry and mechanisms, applications, and research needs. A better understanding of these multifaceted ninhydrin reactions provide a scientific basis for further improvements of this important analytical technique.

Applications of the Ninhydrin Reaction for Analysis of Amino Acids, Peptides, and Proteins to Agricultural and Biomedical Sciences

In recent years, great interest has been focused on using natural antioxidants in food products, due to studies indicating possible adverse effects that may be related to the consumption of synthetic antioxidants. A variety of plant materials are known to be natural sources of antioxidants, such as herbs, spices, seeds, fruits and vegetables. The interest in these natural components is not only due to their biological value, but also to their economic impact, as most of them may be extracted from food by-products and under-exploited plant species. This article provides an overview of current knowledge on natural antioxidants: their sources, extraction methods and stabilization processes. In addition, recent studies on their applications in the food industry are also addressed; namely, as preservatives in different food products and in active films for packaging purposes and edible coatings.

https://www.mdpi.com/1420-3049/24/22/4132/pdf

Antioxidants of Natural Plant Origins: From Sources to Food Industry Applications.

Antioxidant properties of ultrafiltration-recovered soy protein fractions from industrial effluents and their hydrolysates

Preface Introduction The Chemistry of Non-Enzymic Browning Recent Advances Colour Formation in Non-Enzymic Browning Flavour and Off-Flavour Formation in Non-Enzymic Browning Toxicological Aspects Nutritional Aspects Other Physiological Aspects Other Consequences of Technological Significance Implications for Other Fields Non-Enzymic Browning Due Mainly to Ascorbic Acid Caramelisation Inhibition of Non-Enzymic Browning in Foods Inhibition of the Maillard Reaction in Vivo Subject Index

The Maillard reaction : chemistry, biochemistry and implications

Measuring the effects of pesticides on bacterial communities in soil: A critical review

ACE-inhibitory activity of enzymatic protein hydrolysates from lupin and other legumes

Legumes are valuable sources of tocopherols.

The health benefits of sweet lupin seed flours and isolated proteins

Multifunctional peptides for the prevention of cardiovascular disease: A new concept in the area of bioactive food-derived peptides

The seeds of the plants of the Fabaceae, commonly known as “grain legumes” or “pulses,” are major foodstuffs in most countries In addition, these seeds may also provide some health benefits, in particular in the area of hypercholesterolemia and hypertension prevention Whereas the hypocholesterolemic activity of soy protein has been well known for decades and was finally supported by the health claim by the US Food and Drug Administration in 1999, similar information on non-soy legumes is scarce This paper reviews all such available data from animal models and human trials as well as information on the mechanism of action provided by in vitro studies, mainly on cell cultures or assays on specific enzymes This body of data indicates that a regular consumption of grain legumes may be useful both for the prevention of hypercholesterolemia and hypertension More investigations are needed, however, for elucidating the mechanism of action and the actual effective components in legumes

Giovanna Boschin

Papers

ACE-inhibitory activity of enzymatic protein hydrolysates from lupin and other legumes

Legumes are valuable sources of tocopherols.

The health benefits of sweet lupin seed flours and isolated proteins

Multifunctional peptides for the prevention of cardiovascular disease: A new concept in the area of bioactive food-derived peptides

The Role of Grain Legumes in the Prevention of Hypercholesterolemia and Hypertension