Carol Levin

• B.S.
• support scientist, retired at United States Department of Agriculture

The antimicrobial effects of apple‐, carrot‐, and hibiscus‐based edible films containing carvacrol and cinnamaldehyde against Escherichia coli O157:H7 on organic leafy greens in sealed plastic bags were investigated. Fresh‐cut Romaine and Iceberg lettuce, and mature and baby spinach leaves were inoculated with E. coli O157:H7 and placed into Ziploc...

The potential for apple peels to mitigate the deleterious effects of a high-fat diet in mice was investigated here. Mice were fed a high-fat diet supplemented with apple powders from three apple varieties or a commercial apple polyphenol. Polyphenols were characterized using colorimetric assays and high-performance liquid chromatography. Mice were...

Potato peel, a waste product of the potato processing industry, is high in bioactive compounds. We investigated the in vitro antitrichomonad activity of potato peel powders prepared from commercial Russet, red, purple, and fingerling varieties as well as several known potato components, alkaloids and phenolic compounds, against three pathogenic str...

Background Plants produce secondary metabolites that often possess widespread bioactivity, and are then known as phytochemicals. We previously determined that several phytochemical-rich food-derived preparations were active against pathogenic foodborne bacteria. Trichomonads produce disease (trichomoniasis) in humans and in certain animals. Trichom...

Potatoes contain two classes of alkaloids: the glycoalkaloids and the calystegines. The presence of glycoalkaloids in potatoes and their toxicity have been known for more than a century and much has been written about them. Discovery of the nortropane calystegine alkaloids is more recent, and the knowledge of their presence in potatoes even more so...

Marinades for preparing raw meats for cooking are frequently made of wine and herbs. We simulated several formulations of potential antimicrobial marinades with these components and other food compatible/food derived extracts. Red wine formulations containing essential oils from oregano or thyme, or their primary active components carvacrol and thy...

The content of water, free amino acids, amino acid metabolites, crude protein, the carotene pigments β-carotene and lycopene, and 9 characterized and 2 incompletely characterized individual phenolic (flavonoid) compounds of 12 greenhouse-grown cherry tomato varieties of various colors (green, yellow, orange, red, and black) was determined using HPL...

Unlabelled: We evaluated the relative bactericidal activities (BA(50) ) of 10 presumed health-promoting food-based powders (nutraceuticals) and, for comparison, selected known components against the following foodborne pathogens: Escherichia coli O157:H7, Salmonella enterica, Listeria monocytogenes, and Staphylococcus aureus. The relative activiti...

Jujube ( Ziziphus jujube ) was analyzed at eight stages of ripeness (S1-8) for protein, by HPLC and mass spectroscopy for free amino acids and flavonoids, and by colorimetry for total flavonoids and antioxidative activity. The ripe fruit had lower levels of protein, flavonoids, and antioxidative activity than that of the unripe fruit. Free amino ac...

This paper describes a method for determining the nutritional value of D-amino acids, D-peptides, and amino acid derivatives using a growth assay in mice fed a synthetic all-amino acid diet. A large number of experiments were carried out in which a molar equivalent of the test compound replaced a nutritionally essential amino acid such as L-lysine...

The addition of plant essential oils to edible films and coatings has been shown to protect against bacterial pathogens and spoilage while also enhancing sensory properties of foods. This study evaluated the effect of adding 0.5 and 0.75% carvacrol (active ingredient of oregano oil) to apple- and tomato-based film-forming solutions and 0.5 and 0.75...

Partial acid hydrolysis of the tetrasaccharide (lycotetraose) side chain of the tomato glycoalkaloid α-tomatine resulted in the formation of four products with three, two, one, and zero carbohydrate side chains, which were separated by high-performance liquid chromatography (HPLC) and identified by thin-layer chromatography (TLC) and liquid chromat...

Tomato (Solanum lycopersicum) plants synthesize nutrients, pigments, and bioactive compounds that benefit nutrition and human health. The nature and concentrations of these compounds are strongly influenced by varietal factors such as size and color as well as by processing. To better understand how these factors affect the concentration of nutrien...

Fruit pulp and seeds from the jujube plant possess nutritional and medicinal properties. The bioactive components have been shown to vary both with cultivar and with growing conditions. Most studies report the components of varieties from China. We measured free amino acid, individual phenolic, and total phenolic content, and antioxidative activiti...

This paper reviews and interprets a method for determining the nutritional value of D-amino acids, D-peptides, and amino acid derivatives using a growth assay in mice fed a synthetic all-amino acid diet. A large number of experiments were carried out in which a molar equivalent of the test compound replaced a nutritionally essential amino acid such...

We measured six phenolic compounds by HPLC, the total phenolic content by Folin-Ciocalteu, and antioxidative activities by three methods in the sweet potato plant and in home processed roots. Total phenolic content was highest in the leaves. Eight root varieties were partitioned and analyzed for phenolics. The stem end of the root had significantly...

To elucidate the cause of reported pyruvate accumulation in chilled stored cucumbers (Cucumis sativus L.) cv. ‘Toppugurin’, we have examined differences in the extent of incorporation of acetate-1,2-14C into the tricarboxylic acid (TCA) cycle and the specific activity of the enzyme citrate synthase between healthy and chilling-injured cucumber tiss...

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...

In the present study, we evaluated Shiga toxin (Stx2) activity in apple juices by measuring a decrease in dehydrogenase activity of Vero cells with the microculture tetrazolium (MTT) assay. Freshly prepared juice from Red Delicious apples and Golden Delicious apples inhibited the biological activity of the bacterial toxin Stx2 produced by E. coli O...

The methods described in this chapter for the analysis of biologically active anthocyanins, calystegine alkaloids, glycoalkaloids, and hydrolysis products, and phenolic compounds in commercial potatoes, in processed potato products, and in new cultivars can lead to improvements in the precision and reliability of analyses for quality control and fo...

Essential oils (EOs) derived from plants are rich sources of volatile terpenoids and phenolic compounds. Such compounds have the potential to inactivate pathogenic bacteria on contact and in the vapor phase. Edible films made from fruits or vegetables containing EOs can be used commercially to protect food against contamination by pathogenic bacter...

Physical properties as well as antimicrobial activities against Escherichia coli O157:H7, Salmonella enterica, and Listeria monocytogenes of allspice, garlic, and oregano essential oils (EOs) in tomato puree film-forming solutions (TPFFS) formulated into edible films at 0.5% to 3% (w/w) concentrations were investigated in this study. Antimicrobial...

Tomato plants ( Lycopersicon esculentum ) synthesize the glycoalkaloids dehydrotomatine and alpha-tomatine, possibly as a defense against bacteria, fungi, viruses, and insects. Six green and three red tomato extracts were investigated for their ability to induce cell death in human cancer and normal cells using a microculture tetrazolium (MTT) assa...

To develop a better understanding of compositional changes occurring during the production of commercial teas, we determined by high-performance liquid chromatography (HPLC) changes in ingredient levels during each of several manufacturing steps used to produce Kamairi-cha, a premium green tea. Kamairi-cha uses pan-frying instead of the usual blanc...

To help meet the needs of consumers, producers of dietary tea products, and researchers for information on health-promoting tea ingredients, we determined by HPLC 7 catechins [(-)-epigallocatechin (EGC), (-)-catechin (C), (+)-epicatechin (EC), (-)-epigallocatechin 3-gallate (EGCG), (-)-gallocatechin 3-gallate (GCG), (-)-epicatechin 3-gallate (ECG),...

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 fr...

Potato plants synthesize phenolic compounds as protection against bruising and injury from bacteria, fungi, viruses, and insects. Because antioxidative phenolic compounds are also reported to participate in enzymatic browning reactions and to exhibit health-promoting effects in humans, a need exists for accurate methods to measure their content in...

Pepper plants accumulate pungent bioactive alkaloids called piperamides. To facilitate studies in this area, high-performance liquid chromatography (HPLC) and liquid chromatography/mass spectrometry methods were developed and used to measure the following piperamides in 10 commercial whole (peppercorns) and in 10 ground, black, white, green, and re...

The antimicrobial activities against Escherichia coli O157:H7 as well as the stability of carvacrol, the main constituent of oregano oil, were evaluated during the preparation and storage of apple-based edible films made by two different casting methods, continuous casting and batch casting. Antimicrobial assays of films and high-performance liquid...

We have evaluated bactericidal activities against Bacillus cereus, Escherichia coli O157:H7, Listeria monocytogenes, and Salmonella enterica of several antimicrobial wine recipes, each consisting of red or white wine extracts of oregano leaves with added garlic juice and oregano oil. Dose-response plots were used to determine the percentage of the...

We developed wine formulations containing plant essential oils and oil compounds effective against foodborne pathogenic bacteria Escherichia coli O157:H7 and Salmonella enterica. HPLC was used to determine maximum solubility of antimicrobials in wines as well as amounts of antimicrobials extracted by wines from commercial oregano and thyme leaves....

Exposing soy protein to alkaline conditions (pH 8-14) for various time periods (10-480 min), and temperatures (25-95°C at 10°C intervals) destroyed all of the cystine and part of arginine, lysine, serine, and threonine residues. These losses were accompanied by the appearance of lysinoalanine (LAL) and unidentified ninhydrin-positive compounds. Acy...

  To help meet the needs of consumers, producers of dietary tea supplements, and researchers for information on health-promoting tea compounds, we compared the following conditions for the extraction of tea leaves and green tea-containing dietary supplements: 80% ethanol/water at 60 °C for 15 min and boiled water for 5 min. The following 7 catechin...

We evaluated the antimicrobial activities of seven green tea catechins and four black tea theaflavins, generally referred to as flavonoids, as well as the aqueous extracts (infusions) of 36 commercial black, green, oolong, white, and herbal teas against Bacillus cereus (strain RM3190) incubated at 21 degrees C for 3, 15, 30, and 60 min. The results...

We evaluated 17 plant essential oils and nine oil compounds for antibacterial activity against the foodborne pathogens Escherichia coli O157:H7 and Salmonella enterica in apple juices in a bactericidal assay in terms of % of the sample that resulted in a 50% decrease in the number of bacteria (BA(50)). The 10 compounds most active against E. coli (...

Hamsters were fed semipurified diets containing green or red freeze-dried tomato powders. Compared to the control diet devoid of tomatoes, a 59% and 44% reduction low-density lipoprotein (LDL) cholesterol was induced by both the green and red tomatoes, respectively. The corresponding reductions in very low-density lipoproteins (VLDL) were 45% and 3...

A variety of methods are used to analyze tomato glycoalkaloids. Because no single method has gained wide acceptance,the extraction and analysis of tomatine by HPLC with pulsed amperometric detection (PAD) was previously optimized for standard and transgenic tomatoes and processed tomato products. In the course of these studies it was discovered tha...

Glycoalkaloids (GA's) represent an important group of naturally occurring plant toxins. They are found in a wide variety of plants including potato and tomato. Analysis of GA's is complicated, particularly in tomato because these compounds do not readily absorb in the UV. Thus, extensive sample cleanup is usually required followed by HPLC. In this...

Tomato plants (Lycopersicon esculentum) synthesize the glycoalkaloid a-tomatine, possibly as a defense against insects and other pests. As part of an effort to improve the safety of plant foods, the usefulness of a new HPLC pulsed amperometric detection (PAD) method for the direct analysis of cx-tomatine in different parts of the tomato plant; in s...

As part of a program to control the biosynthesis of glycoalkaloids, we used an improved HPLC method with pulsed amperometric detection (PAD) to measure the alpha-tomatine content of store-bought and field-grown, including transgenic, red, and green tomatoes. The HPLC method responded linearly to alpha-tomatine in the range 0.125-12.5 micrograms, su...

As part of a program of potato improvement, improved procedures were developed for reversed-phase high-performance liquid chromatographic (HPLC) separation of the alkaloids present in commercial potatoes: the two major glycoalkaloids, alpha-chaconine and alpha-solanine; hydrolysis products or metabolites derived from these two compounds, the so-cal...

Bulk commercial grain, such as soybeans and wheat, may be contaminated by nongrain impurities, including jimson weed seeds, that coexist with the crop to be harvested. The present study was undertaken to determine the content of the major alkaloids of jimson weed seeds, atropine and scopolamine, as well as protein, carbohydrate, fat, mineral, hemma...