R.D. Phillips

Plant Food-Derived Angiotensin I Converting Enzyme Inhibitory Peptides

Hypertension is one of the most common worldwide diseases that afflict humans. Angiotensin I converting enzyme (ACE) catalyzes the formation of vasoconstrictor, angiotensin II, and the inactivation of vasodilator, bradykinin. The influences of ACE on blood pressure make it an ideal target clinically and nutritionally in the treatment of hypertension. A number of animal food-derived peptides have been reviewed about their in vitro and in vivo ACE inhibitory activities. The aim of this review is to discuss the plant food-derived angiotensin I converting enzyme (ACE) inhibitory peptides from sources, production, purification, and structure to in vitro and in vivo activities.

Cowpea flour: A potential ingredient in food products

Cowpeas (Vigna unguiculata L. Walp) are an important grain legume in East and West African countries as well as in other developing countries. The U.S. is the only developed country producing large amounts of cowpeas. High protein (18 to 35%) and carbohydrate (50 to 65%) contents, together with an amino acid pattern complementary to that of cereal grains, make cowpeas potentially important to the human diet from a nutritional standpoint. Despite their potential as an inexpensive source of protein and energy, cowpeas are underutilized in the U.S. and other industrialized countries. A simple technology for preparing cowpea flour would stimulate increased consumption of this legume. This paper reviews the status of cowpea flour production technologies and uses of cowpea flour in various food products.

Three key proteases – angiotensin-I-converting enzyme (ACE), ACE2 and renin – within and beyond the renin-angiotensin system

Summary The discovery of angiotensin-I-converting enzyme 2 (ACE2) and a (pro)renin receptor has renewed interest in the physiology of the renin-angiotensin system (RAS). Through the ACE2/angiotensin-(1–7)/Mas counter-regulatory axis, ACE2 balances the vasoconstrictive, proliferative, fibrotic and proinflammatory effects of the ACE/angiotensin II/AT1 axis. The (pro)renin receptor system shows an angiotensin-dependent function related to increased generation of angiotensin I, and an angiotensin-independent aspect related to intracellular signalling. Activation of ACE2 and inhibition of ACE and renin have been at the core of the RAS regulation. The aim of this review is to discuss the biochemistry and biological functions of ACE, ACE2 and renin within and beyond the RAS, and thus provide a perspective for future bioactives from natural plant and/or food resources related to the three proteases.

Starchy legumes in human nutrition, health and culture

Starchy legumes have been consumed by humans since the earliest practice of agriculture and have been ascribed medicinal and cultural as well as nutritional roles. They are an important component of the diet in the developing countries in Africa, Latin America, and Asia where they are especially valuable as a source of dietary protein to complement cereals, starchy roots and tubers. Legumes contain 20–30% protein which is generally rich in lysine and limiting in sulfur amino acids. The nutritional quality of legume protein is limited by the presence of both heat labile and heat stable antinutrients as well as an inherent resistance to digestion of the major globulins. In addition to its nutritional impact, legume protein has been shown to reduce plasma low density lipoprotein when consumed. Legume starch is more slowly digested than starch from cereals and tubers and produces less abrupt changes in plasma glucose and insulin upon ingestion. Starchy legumes are also valuable sources of dietary fiber as well as thiamin and riboflavin. Starchy legumes are a valuable component of a prudent diet, but their consumption is constrained by low yields, the lack of convenient food applications, and flatulence.

Antibacterial Activities of Blueberry and Muscadine Phenolic Extracts

Phenolics are one category of phyto-antimicrobials that refer to the antimicrobial substances extracted from plant sources. This study was undertaken to determine the influence of blueberry and muscadine phenolic extracts on the growths of 2 important foodborne bacterial pathogens, Salmonella Enteritidis and Listeria monocytogenes. Cells of S. Enteritidis (n = 4) or L. monocytogenes (n = 4) strains were inoculated (3 log CFU/mL) into tryptic soy broth (TSB) supplemented with 46.25 ppm of muscadine phenolics and 24 ppm of blueberry phenolics, respectively. The inoculated and un-inoculated broth with or without the supplemented phenolics were incubated at 37 °C for 24 h. Samples were drawn periodically, and cell populations of Salmonella and Listeria were determined on tryptic soy agar (TSA). It was observed that Salmonella was relatively more susceptible than Listeria to the phenolic extracts used in the study. The growth of Salmonella was significantly inhibited in all samples at all sampling points except for the sample that was supplemented with muscadine water extract and drawn at the 24-h sampling point. Blueberry phenolics were relatively more effective than muscadine phenolic extracts in inhibiting the growth of Salmonella. One tested strain of Listeria was more susceptible to ethanol than water phenolic extracts. The study revealed the potentials and limitations of using blueberry and muscadine phenolics to control the growths of selected Salmonella and Listeria strains.

Functional characteristics of cowpea (Vigna unguiculata) flour and starch as affected by soaking, boiling, and fungal fermentation before milling

Abstract Functional characteristics of cowpea flour and starch as affected by soaking, soaking and boiling (S/B), and fermentation of seeds with Rhizopus microsporus var. oligosporus before milling were investigated. Soaking and fungal fermentation had fewer effects on flour and starch functionality compared to boiling. Boiling drastically reduced foamability and thus increased specific gravity of whipped cowpea paste. The gradual increase in total color differences of pastes prepared from S/B seeds with or without fermentation was due to a gradual decrease in lightness (L∗). The more intense yellow color observed in whipped pastes from S/B seeds after fermentation was due to increased b∗ and decreased L∗ values. Starch from all treatments had greater swelling volume than flour. Significant reductions in swelling volume of flour and starch were due to the boiling treatment. Pasting characteristics of control flour and starch are concentration dependent. The pasting curve pattern of cowpea flour differed markedly from that of cowpea starch.

Changes in fatty acid, simple sugar, and oligosaccharide content of cowpea (Vigna unguiculata) flour as a result of soaking, boiling, and fermentation with Rhizopus microsporus var. oligosporus

Changes in fatty acid, simple sugar, and oligosaccharide content of cowpea flour as a result of soaking, boiling, and fermentation with Rhizopus microsporus var. oligosporus were investigated. The major fatty acids in flour made from both nonfermented and fermented cowpeas were linoleic, palmitic, and linolenic. With the exception of lower amounts of lauric, palmitic, linoleic, and linolenic acids and slightly higher amounts of lignoceric acid, the remaining fatty acids in flour made from soaked cowpeas were essentially unchanged from the control flour made from cowpeas that were not soaked, boiled or fermented. Soaking followed by boiling generally increased amounts of fatty acids in flour compared to the control. Rhizopus microsporus did not utilize lipid during 24 h of fermentation. Soaking decreased the amount of sucrose and stachyose by 39% and 18.4%, respectively, whereas soaking followed by boiling caused decreases of 58.3% and 49.3%. Complete elimination of sucrose, raffinose, and stachyose was achieved after 15 h of fermentation.

Effect of processing on some properties of cowpea (Vigna unguiculata), seed, protein, starch, flour and akara

Large brown eye Kano white cowpea (Vigna unguiculata) seeds were processed into three batches of flour by wetting, drying individually at 30, 80, and 120 degrees C, decorticating and dry milling. Starch was extracted from the cowpea seed and protein from the flour using water as solvent. The water-extractable proteins were purified by dialysis and analysed by electrophoresis. The cowpea flour was used to produce akara balls (fried paste). The microstructure of the cowpea cotyledon, flour, starch and akara crumb were examined with a scanning electron microscope (SEM). Electrophoretic separation revealed that some of the protein fractions from the sample extracted from 30 degrees C dried cowpea were absent in the sample extracted from the 80 degrees C and 120 degrees C dried cowpeas or their quantities had decreased. In the SEM study, no difference was observed in the microstructure of the three flour samples except in the size and shape of the starch granules and particles of protein and cell wall material. The starch granules from the cowpea dried at 120 degrees C had surface defects. Cavities occurred in the cotyledons of the 80 and 120 degrees C dried cowpea seeds, some starch granules, protein matrix and sometimes the entire cell contents were lost from the cell. The protein sheet in the akara crumb became thicker as temperature increased to 80 and 120 degrees C.

Purification, activity and sequence of angiotensin I converting enzyme inhibitory peptide from alcalase hydrolysate of peanut flour.

Peanut hydrolysate obtained after 6 h of digestion by Alcalase was used to isolate angiotensin I converting enzyme (ACE) inhibitory peptides. After centrifugation and ultrafiltration through a 0.2 microm nylon filter, the hydrolysate was filtered through the polyethersulfone membrane with a molecular weight cutoff (MWCO) of 10 kDa. The resulting permeate was then separated by primary reverse-phase high performance liquid chromatography (RP-HPLC). Eluate was divided into six major fractions according to eluation time. The fraction with eluting time 50-60 min showed the most potent ACE inhibition and was subjected to further purification by the secondary RP-HPLC. Four peaks were found to have strong ACE inhibitory activities, and their IC(50) values were determined. Peptide mass for the most potent peak was obtained by matrix-assisted laser desorption and ionization (MALDI), and sequence was determined by MALDI tandem TOF-TOF (time-of-flight) mass spectrometer (MS/MS) to be Lys-Ala-Phe-Arg.

Survival of Lactobacillus rhamnosus GG as Influenced by Storage Conditions and Product Matrixes

Mortality resulting from diarrhea especially that occurs in children younger than 5 y of age ranks 3rd among all deaths caused by infectious diseases worldwide. Probiotics such as Lactobacillus rhamnosus GG are clinically shown to effectively reduce the incidence of diarrhea in children. A food substrate is one of the major factors regulating the colonization of microorganisms in human gastrointestinal tracts. Peanut butter is a nutritious, low-moisture food that could be a carrier for probiotics. In this study, we observed the influence of storage conditions and product matrixes on the survival of L. rhamnosus GG. Cells of L. rhamnosus GG were inoculated into full fat or reduced fat peanut butter at 10(7) CFU/g. Inoculated peanut butter was stored at 4, 25, or 37 °C for 48 wk. Samples were drawn periodically to determine the populations of L. rhamnosus GG. Results showed that there was no significant decrease in the viable counts of L. rhamnosus GG in products stored 4 °C. The survivability of L. rhamnosus GG decreased with increasing storage temperature and time. Product matrixes did not significantly affect the survival of L. rhamnosus GG except at 37 °C. Populations of L. rhamnosus GG were preserved at >6 logs in products stored at 4 °C for 48 wk and at 25 °C for 23 to 27 wk. At 37 °C, the 6-log level could not be maintained for even 6 wk. The results suggest that peanut butter stored at 4 and 25 °C could serve as vehicles to deliver probiotics.