Dietary Significance of Processing‐Induced D‐Amino Acids

Friedman, Mendel

doi:10.1002/9780470430101.ch6b

Cited by 3 publications

(4 citation statements)

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“…As reviewed in detail elsewhere, 33 because all amino acids residues in a protein undergo racemization simultaneously, but at different rates, 34 assessment of the extent of racemization in a protein requires quantitative measurement of ~40 l - and d -optical isomers. A discussion of reported methods used to analyze the isomeric forms of amino acids simultaneously is beyond the scope of this article.…”

Section: The Analysis Of Tryptophan In Food Body Fluids and Tissuesmentioning

confidence: 99%

Analysis, Nutrition, and Health Benefits of Tryptophan

Friedman

2018

Int J�Tryptophan�Res

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168

119

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Tryptophan is an essential plant-derived amino acid that is needed for the in vivo biosynthesis of proteins. After consumption, it is metabolically transformed to bioactive metabolites, including serotonin, melatonin, kynurenine, and the vitamin niacin (nicotinamide). This brief integrated overview surveys and interprets our current knowledge of the reported multiple analytical methods for free and protein-bound tryptophan in pure proteins, protein-containing foods, and in human fluids and tissues, the nutritional significance of l-tryptophan and its isomer d-tryptophan in fortified infant foods and corn tortillas as well the possible function of tryptophan in the diagnosis and mitigation of multiple human diseases. Analytical methods include the use of acid ninhydrin, near-infrared reflectance spectroscopy, colorimetry, basic hydrolysis; acid hydrolysis of S-pyridylethylated proteins, and high-performance liquid and gas chromatography-mass spectrometry. Also covered are the nutritional values of tryptophan-fortified infant formulas and corn-based tortillas, safety of tryptophan for human consumption and the analysis of maize (corn), rice, and soybean plants that have been successfully genetically engineered to produce increasing tryptophan. Dietary tryptophan and its metabolites seem to have the potential to contribute to the therapy of autism, cardiovascular disease, cognitive function, chronic kidney disease, depression, inflammatory bowel disease, multiple sclerosis, sleep, social function, and microbial infections. Tryptophan can also facilitate the diagnosis of certain conditions such as human cataracts, colon neoplasms, renal cell carcinoma, and the prognosis of diabetic nephropathy. The described findings are not only of fundamental scientific interest but also have practical implications for agriculture, food processing, food safety, nutrition, and animal and human health. The collated information and suggested research need will hopefully facilitate and guide further studies needed to optimize the use of free and protein-bound tryptophan and metabolites to help improve animal and human nutrition and health.

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Section: The Analysis Of Tryptophan In Food Body Fluids and Tissuesmentioning

confidence: 99%

Analysis, Nutrition, and Health Benefits of Tryptophan

Friedman

2018

Int J�Tryptophan�Res

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168

119

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“…These include embryotoxic , and cancer cell-inhibiting glycoalkaloids , , , glycosidase-inhibiting calystegine alkaloids , , potato phenolic compounds , biologically active enzyme inhibitors , and degradation products of vitamin C present in cereal and potato products – . In addition, cross-linked amino acids (lysinoalanine) , – , d -amino acids , , nonenzymatic and enzymatic browning products , , , imidazolines , phenolic degradation products , and soybean enzyme inhibitors and lectins – as well as other naturally occurring antioxidative, antimutagenic, and anticarcinogenic polyphenolic compounds (anthocyanins, catechins, theaflavins, flavonoids) present in other vegetables, fruits, teas, and dark rice brans , , – and the anticarcinogenic amino acid theanine present in teas as well as pungent capsaicinoids and piperines present in peppers – may also affect the toxic manifestations of dietary acrylamide. A striking example is our recent finding that dietary tomatine, previously found to be embryotoxic in frog assays , was not only nontoxic to rainbow trout but actually protected the fish against dibenzopyrine (DBP)-induced liver and stomach tumors .…”

Section: Bioavailablity and Mitigation Of Toxicitymentioning

confidence: 99%

“…Foods are processed for a variety of reasons: to render them edible if they are not; to permit storage; to alter texture and flavor; and to destroy microorganisms, undesirable enzymes, and other toxins – . Processing methods include heating (baking, cooking, frying, microwaving), freezing, aging, and exposure to acidic and basic conditions.…”

Section: Introductionmentioning

confidence: 99%

Review of Methods for the Reduction of Dietary Content and Toxicity of Acrylamide

Friedman

Levin

2008

J. Agric. Food Chem.

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243

206

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Potentially toxic acrylamide is largely derived from heat-induced reactions between the amino group of the free amino acid asparagine and carbonyl groups of glucose and fructose in cereals, potatoes, and other plant-derived foods. This overview surveys and consolidates the following dietary aspects of acrylamide: distribution in food originating from different sources; consumption by diverse populations; reduction of the acrylamide content in the diet; and suppression of adverse effects in vivo. Methods to reduce adverse effects of dietary acrylamide include (a) selecting potato, cereal, and other plant varieties for dietary use that contain low levels of the acrylamide precursors, namely, asparagine and glucose; (b) removing precursors before processing; (c) using the enzyme asparaginase to hydrolyze asparagine to aspartic acid; (d) selecting processing conditions (pH, temperature, time, processing and storage atmosphere) that minimize acrylamide formation; (e) adding food ingredients (acidulants, amino acids, antioxidants, nonreducing carbohydrates, chitosan, garlic compounds, protein hydrolysates, proteins, metal salts) that have been reported to prevent acrylamide formation; (f) removing/trapping acrylamide after it is formed with the aid of chromatography, evaporation, polymerization, or reaction with other food ingredients; and (g) reducing in vivo toxicity. Research needs are suggested that may further facilitate reducing the acrylamide burden of the diet. Researchers are challenged to (a) apply the available methods and to minimize the acrylamide content of the diet without adversely affecting the nutritional quality, safety, and sensory attributes, including color and flavor, while maintaining consumer acceptance; and (b) educate commercial and home food processors and the public about available approaches to mitigating undesirable effects of dietary acrylamide.

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“…Free amino acids represent a source of nitrogen and of nutritionally essential amino acids such as lysine, methionine, and threonine. On the other hand, during processing they can be converted to or be precursors for potentially deleterious compounds such as D-amino acids (4) or Maillard browning products. Free L-asparagine is the major precursor for potentially toxic acrylamide, found in processed foods (5).…”

Section: Introductionmentioning

confidence: 99%

Changes in Free Amino Acid, Phenolic, Chlorophyll, Carotenoid, and Glycoalkaloid Contents in Tomatoes during 11 Stages of Growth and Inhibition of Cervical and Lung Human Cancer Cells by Green Tomato Extracts

Choi¹,

Lee²,

Kim

et al. 2010

J. Agric. Food Chem.

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Tomato ( Solanum lycopersicum ) plants synthesize nutrients, pigments, and secondary metabolites that benefit nutrition and human health. The concentrations of these compounds are strongly influenced by the maturity of the tomato fruit on the vine. Widely consumed Korean tomatoes of the variety Doturakworld were analyzed for changes in the content of free amino acids, phenolic compounds, chlorophylls, carotenoids, and glycoalkaloids at 11 stages (S1-S11) of ripeness. The results show that (a) the total content (in mg/100 g of FW) of the free amino acids and other nitrogen-containing compounds in the extracts ranged from about 41 to 85 in the green tomato extracts S1-S7 and then increased to 251 (S9) in the red extracts, followed by a decrease to 124 in S11 red extracts; (b) the total initial concentration and composition of up to 12 phenolic compounds of approximately 2000 microg/100 g of FW varied throughout the ripening process, with the quantity decreasing and the number of individual compounds increasing in the red tomato; (c) chlorophyll a and b content of tomatoes harvested during S1 was 5.73 mg/100 g of fresh pericarp and then decreased continuously to 1.14 mg/100 g for S11; (d) the concentration (in mg/100 g of FW) of lycopene in the S8 red extract of 0.32 increased to 1.27 in S11; and (e) tomatoes harvested during S1 contained 48.2 mg of dehydrotomatine/100 g of FW, and this value continually decreased to 1.5 in S7, with no detectable levels in S8-S11. The corresponding alpha-tomatine content decreased from S1 (361) to S8 (13.8). The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) cell assay IC(50) values showed that Hel299 lung cells, A549 lung cancer cells, and HeLa cervical carcinoma cells were highly susceptible to inactivation by glycoalkaloid-rich green tomato extracts. Chang normal liver cells and U937 lymphoma cells were less susceptible. The possible significance of the results for plant physiology and the diet is discussed.

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Dietary Significance of Processing‐Induced D‐Amino Acids

Cited by 3 publications

References 122 publications

Analysis, Nutrition, and Health Benefits of Tryptophan

Analysis, Nutrition, and Health Benefits of Tryptophan

Review of Methods for the Reduction of Dietary Content and Toxicity of Acrylamide

Changes in Free Amino Acid, Phenolic, Chlorophyll, Carotenoid, and Glycoalkaloid Contents in Tomatoes during 11 Stages of Growth and Inhibition of Cervical and Lung Human Cancer Cells by Green Tomato Extracts

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