Changing the Landscape: An Introduction to the Agricultural and Food Chemistry Technical Program at the 258th American Chemical Society National Meeting in San Diego.

This special issue of the Journal of Agricultural and Food Chemistry (JAFC) is a highlight of the Agricultural and Food Chemistry Division (AGFD) technical program at the 258th National Meeting of the American Chemical Society (ACS) in San Diego, CA, U.S.A., on August 25-29, 2019. At the conference, AGFD had 44 oral sessions at 19 symposia and 100 poster presentations with more than 400 abstract submissions. The technical program covered a broad range of current research and development topics in agricultural and food chemistry, including bioactive food components, diet and human nutrition, utilization of agricultural materials in food systems, food packaging, nanotechnology, and food safety, as well as several special award symposia. This is the first JAFC special issue that highlights an ACS national meeting program with joint efforts from AGFD.

Synbiotic Effect of Whole Grape Seed Flour and Newly Isolated Kefir Lactic Acid Bacteria on Intestinal Microbiota of Diet-Induced Obese Mice.

Alterations of intestinal microbiota by synbiotic action of pre- and probiotics may confer health benefits to the host. In this study, high-throughput sequencing of 16S rRNA was used to analyze intestinal microbiota in feces, and the relative abundance of intestinal bacteria was correlated with physiological data from a prior study of a synbiotic combination of flavonoid-rich wine grape seed flour (WGF) and two newly isolated kefir lactic acid bacteria (LAB) in diet-induced obese mice. The combination of WGF and LAB enhanced observed operational taxonomic units and Chao1 index compared to WGF alone, indicating an increase in the microbial community richness. The combination significantly enhanced abundance of Akkermansia muciniphila and Nocardia coeliaca and their abundance had an inverse relationship with body weight gain and adipose weight. In conclusion, the synbiotic effects of WGF and LAB on improvement of high-fat-diet-induced obesity are strongly linked to remodeling intestinal microbiota.

Hypocholesterolemic Effects of Expeller-Pressed and Solvent-Extracted Fruit Seed Oils and Defatted Pomegranate Seed Meals.

Consumptions of fruit seed oils and meals could potentially improve cardiovascular health by reducing plasma total cholesterol and low-density lipoprotein (LDL). The study objective was to compare the effectiveness of expeller-pressed and solvent-extracted grape, tomato, pomegranate seed oils, and defatted pomegranate meals in lowering plasma and hepatic cholesterol using hamster models. Hamsters were fed with fruit seed oils (FSO), defatted pomegranate seed meals (PDM), or control diets. After a 3-week feeding period, plasma total triglycerides of treatment diets were significantly lower. FSO also reduced total, very-low-density lipoprotein- (VLDL), and LDL-cholesterols, while PDM only lowered VLDL-cholesterols. Decreases in low-density and high-density lipoproteins (LDL/HDL) ratios were also observed in most treatments. In liver, triglycerides, total, and free cholesterol levels did not vary between control and treatments. There were no significant differences in lipid modulating properties between solvent-extracted and expeller-pressed oils. In conclusion, partial replacements of saturated fat in high-fat diets with tomato, pomegranate, and grape seed oils could effectively reduce plasma triglyceride levels and improve HDL/LDL ratios.

Dietary Supplementation of Potato Peel Powders Prepared from Conventional and Organic Russet and Non-organic Gold and Red Potatoes Reduces Weight Gain in Mice on a High-Fat Diet.

The present study investigated the potential of potato peel powders, high in bioactive phenolic compounds and glycoalkaloids, to reduce weight gain in mice consuming a high-fat diet. Potato peel powders were prepared from the following fresh commercial potato varieties by hand-peeling and then freeze-drying and grinding the peels into powder: non-organic (conventionally grown) gold, red, and Russet and organically grown Russet. Mice diets (25% fat by weight) were supplemented with either 10 or 20% potato peel powders for 3 weeks. In comparison to the control diet, the isocaloric and isonitrogenous peel-containing diets induced a reduction in weight gain that ranged from 17-45% (10% peel diets) to 46-73% (20% peel diets), suggesting that differences in weight gain are associated with the potato peel source and peel concentration of the diet. Weight reductions were accompanied by reduced epididymal white adipose tissue ranging from 22 to 80% as well as changes in the microbiota analyzed using next-generation sequencing and in obesity-associated genetic biomarkers determined by the quantitative real-time polymerase chain reaction. Safety aspects and possible mechanisms of the antiobesity effects are discussed in terms of the composition of the bioactive potato peel compounds, which were determined using high-performance liquid chromatography. The results suggest that potato peels, a major peeling byproduct of potato processing used to prepare fries, chips, and potato flour, that showed exceptionally high antiobesity properties in fat mice, have the potential to serve as an antiobesity functional food.

Polysaccharide gel coating of the leaves of Brasenia schreberi lowers plasma cholesterol in hamsters.

Brasenia schreberi ( chún cài) is an invasive aquatic weed found in the USA, but the plant has economic value in Asia where it is cultivated for food. The young leaves of B. schreberi are coated with gelatinous water-insoluble mucilage. This mucilage is a polysaccharide composed of galactose, mannose, fucose, and other monosaccharides. Because some carbohydrate gels are hypocholesterolemic, we evaluated their cholesterol-lowering properties in male hamsters fed hypercholesterolemic diets containing 2% gel coat from B. schreberi (GEL), or 1% cholestyramine (CA), or 5% hydroxypropyl methylcellulose (HPMC), and compared them to 5% microcrystalline cellulose (control) for 3 weeks. We found that very-low-density lipoprotein-, low-density lipoprotein-, and total-cholesterol concentrations in plasma were significantly lowered by GEL, CA, and HPMC compared to control. High-density lipoprotein-cholesterol concentration was lowered by CA and HPMC. Body weights and abdominal adipose tissue weight of GEL and control group animals were greater than those of the CA and HPMC groups. Fecal lipid excretion was greater in the CA and HPMC groups than in the control group. Expression of hepatic CYP51 and CYP7A1 mRNA was upregulated by CA, HPMC, and GEL, indicating increased hepatic cholesterol and bile acid synthesis. Expression of low-density lipoprotein receptor mRNA was upregulated by all treatments. These results suggest that modulation of hepatic expression of cholesterol and bile acid metabolism-regulated genes contributes to the cholesterol-lowering effects of GEL.

Change in texture improvement of low-fat tofu by means of low-fat soymilk protein denaturation.

BACKGROUND: Tofu made from low-fat soy flour is a nutritional food for consumers and economically benefits the food processor. However, low-fat tofu has poor textural quality, especially insufficient firmness. Stepwise heating (heating at 75 °C, followed by holding at 95 °C) of full-fat soymilk increases gel properties. Therefore we evaluated the two-step heating of low-fat soymilk to improve tofu texture. RESULTS: The denaturation enthalpy and temperature of ß-conglycinin and glycinin were higher in low-fat tofu compared to high-fat tofu. The viscosity of low-fat soymilk and texture of tofu by one-step heating were weaker than full-fat soymilk and tofu. However, the two-step heating increased free sulfhydryl groups and viscosity of low-fat soymilk to a value higher or similar to conventional soymilk. The syneresis of low-fat tofu was reduced about 30% and hardness was higher (131.0 N) by the two-step process compared to one-step heating of full-fat tofu (101.4 N) by the one-step process. The microstructure of low-fat tofu became finer, denser and more homogeneous by the two-step heat process. CONCLUSION: Low-fat tofu produced by denaturing the two major soy proteins separately had improved textural qualities similar to full-fat tofu as a result of increased hydrophobic interactions between denatured protein molecules.

Effect of polysaccharides on the gelatinization properties of cornstarch dispersions.

Konjac glucomannan (KG, neutral), carboxymethylcellulose (CMC, negatively charged), and chitosan (positively charged) were added to cornstarch dispersions to study the effect of polysaccharide-starch interactions on starch gelatinization properties. Pasting and retrogradation properties were measured with a rheometer and DSC. Swelling properties of the starch granules were determined by solubility index, swelling power, and particle size distribution. Depending on the nature of the different polysaccharides, viscosities of cornstarch dispersions were affected differently. The particle size distributions were not influenced by the addition of any of the polysaccharides. Swelling results showed that the KG and CMC molecules interacted with the released or partly released amylose in the cornstarch dispersions. This was correlated with the short-term retrogradation of the starch pastes being retarded by the additions of KG and CMC. However, the chitosan molecules appeared not to associate with the amylose, so the retrogradation of the chitosan-cornstarch dispersions was not retarded.

Concentration-dependent displacement of cholesterol in micelles by hydrophobic rice bran protein hydrolysates.

BACKGROUND: Rice bran, containing about 100-150 g kg(-1) protein, is a by-product of rice milling that has only become an available ingredient in recent years owing to the centralisation of rice milling. Rice bran, but not its protein fraction or hydrolysates, has been shown to have a hypocholesterolaemic effect. Peptides from soy, milk and other foods have been proposed to have hypocholesterolaemic effects based on their ability to lower cholesterol solubility in bile acid/phosphotidyl choline micelles. RESULTS: Rice bran protein hydrolysates (RBPHs) were prepared and investigated for their potential to lower cholesterol concentration in micelles. The RBPHs were produced by digestion using four different peptidases, alcalase 2.4L(®), neutrase 0.8L(®), papaya latex papain and porcine pancreas trypsin, and then fractionated by hydrophobicity using styrene/divinylbeneze resins. Alcalase 2.4L(®) produced the highest degree of hydrolysis, and the resulting hydrolysates had the highest micellar cholesterol inhibition ability in an in vitro hypocholesterolaemic test. The adsorption dynamics of four different macroporous resins, DA201-C, Sepabeads SP207 and SP825 and Diaion HP20, were determined using the Langmuir isotherm model. DA201-C had the highest adsorption capacity with an equilibrium concentration of 220 mg g(-1). The hydrolysates eluted with 25, 50, 75 and 95% (v/v) ethanol lowered the micellar cholesterol concentration by 11.88, 14.76, 19.37 and 7.56% respectively. CONCLUSION: A hydrophobic fraction of RBPH had the highest inhibitory activity on micellar cholesterol, which suggests that it may have hypocholesterolaemic properties.

Physical and sensory properties of all-barley and all-oat breads with additional hydroxypropyl methylcellulose (HPMC) ß-glucan.

Hydroxypropyl methylcellulose (HPMC) is a substituted cellulose that reduces serum cholesterol at modest intake levels. HPMC has also been used for decades in gluten-free breads at a level to optimize loaf volume. Because consumers resist the consumption of whole wheat breads, the sensory and physical properties of all oat and barley breads incorporating HPMC were evaluated. Oat and barley also contain ß-glucan, a glucose polymer similar to HPMC that also lowers cholesterol. The textural and sensory properties of the breads were determined by instrumental and chemical methods and sensory panels. HPMC increased the loaf volume of the breads by up to 2 times and decreased hardness immediately after baking and after up to 3 days of storage. Barley bread with HPMC was rated the highest in overall acceptability by sensory panelists compared to oat and wheat breads with or without HPMC.

Determination of F2-isoprostanes in urine by online solid phase extraction coupled to liquid chromatography with tandem mass spectrometry.

F(2)-isoprostanes are a unique class of prostaglandin-like compounds formed in vivo, which have been established as biomarkers of oxidative stress. Accurate analysis has been challenging due to lack of specificity for the isoforms of isoprostanes and lengthy sample preparation procedures to enable trace quantitative analysis. A quantitative analytical method was developed for the determination of F(2)-isoprostanes in rat and hamster urine by online solid phase extraction (SPE) coupled with liquid chromatography and tandem mass spectrometry (LC-MS/MS). The online SPE LC-MS/MS procedure has significant advantages over alternative methods with respect to specificity, sensitivity, simplicity, and speed. The assay enables the detection of iPF(2alpha)-III, iPF(2alpha)-IV, and iPF(2alpha)-VI over a linear dynamic range of 0.1-50 ng/mL in rat urine samples. This range covers the basal levels of these F(2)-isoprostanes. The limit of quantitation (LOQ) for the standard isoprostanes was about 0.3 ng/mL. The average recoveries ranged from 73 to 115% depending upon the individual F(2)-isoprostane isomers in rat urine. Additionally, the method was used to determine increases of endogenous urine iPF(2alpha)-VI and iPF(2alpha)-III in hamsters challenged with either low-fat or high-fat diets.

Quantification of the sulfated cholecystokinin CCK-8 in hamster plasma using immunoprecipitation liquid chromatography-mass spectrometry/mass spectrometry.

Cholecystokinin (CCK) and the different molecular forms of CCK are well established as biomarkers for satiety but accurate analysis has been limited by the multiple naturally occurring forms and extensive similarities to gastrin. Changes in levels of one form, CCK-8, a naturally occurring eight amino acid peptide of CCK, have been correlated with satiety responses. Endogenous CCK-8 has not been well characterized in Syrian Golden hamsters, an important model in the study of fat uptake and digestion. We have cloned and sequenced hamster CCK and identified and characterized endogenous CCK-8 from hamster plasma. Hamster CCK-8 is composed of eight amino acid residues which are highly conserved among other species. Following accurate identification and characterization of hamster CCK-8, we have developed a highly specific and sensitive immunoprecipitation based LC-MS/MS assay for its quantification. The present assay enables determination of active CCK-8 over a concentration range from 0.05 to 2.5 ng/mL in hamster plasma samples. This range covers both the basal and postprandial levels of CCK-8. Method performance validation samples were examined at three concentrations replicated over the course of 4 days. The assay accuracy (percent relative error, % RE) average was 11.3% with a precision (percent coefficient of variation, % CV) of 15.5% over all samples in this 4 day period. Additionally, the method was used to determine increases of endogenous plasma CCK-8 in hamsters challenged with a high-fat meal.

Simultaneous characterization of bile acid, sterols, and determination of acylglycerides in feces from soluble cellulose-fed hamsters using HPLC with evaporative light-scattering detection and APCI-MS.

The rapid rise in obesity-related diseases has increased interest in oral and dietary agents that disrupt fat metabolism, resulting in the excretion of dietary lipids in the feces. In this study, a rapid and convenient liquid chromatography method to comprehensively analyze fecal lipids in a single injection was developed. An evaporative light-scattering detector (ELSD) for routine analysis or atmosphere pressure chemical ionization tandem mass spectrometry [(+)APCI-MS/MS] for structural confirmation and peak purity was used. The method was applied to characterize lipid components of feces from hamsters fed high-fat diets with either 5% microcrystalline cellulose or 5% hydroxypropyl methylcellulose (HPMC) fibers, to test the effect of HPMC on lipid metabolism. HPMC is a nonfermentable, soluble cellulose fiber. The fecal lipid components identified using this method includes two secondary bile acids, deoxycholic acid, lithocholic acid, and neutral sterols including cholesterol, coprostanol, stigmastanol, and sitosterol. The profile of fecal lipid components was compared between two groups. It was found that the bile acid excretion was increased 2-fold in HPMC-fed hamsters. More interestingly, diacylglycerides and triacylglycerides were detected in feces from hamsters on HPMC-included high-fat diets. We believe that this is the first report of excretion of acylglycerides following neutral soluble fiber feeding.

Viscoelastic properties of waxy and nonwaxy rice flours, their fat and protein-free starch, and the microstructure of their cooked kernels.

Physicochemistry and structural studies of two types of japonica rice, low amylose Calmochi-101 (CM101) and intermediate amylose M-202 (M202), were conducted to determine similarities and differences between the rices perhaps attributable to amylose content differences. The rheological behavior of the gelation and pasting processes of flours and starches was determined with high accuracy and precision using a controlled stress rheometer. Fat and protein, although minor constituents of milled rice, were shown to have significant effects on the physicochemical and pasting properties of starches and flours. Removal of protein and lipids with aqueous alkaline or detergent solutions caused lower pasting temperatures and higher overall viscosity in both starches, compared with their respective flours. There was less viscosity difference between M202 flour and its starch when isolated by enzymatic hydrolysis of protein. The protease did not reduce internally bound lipids, suggesting that fats help to determine pasting properties of rice flours and their respective starches. Structural integrity differences in individual granules of waxy and nonwaxy rice flours, starches, and whole raw, soaked, and cooked milled grain were revealed by fracture analysis and scanning electron microscopy. Calmochi 101 and M202 did not differ in weight-averaged molar mass (Mw) and root-mean-square radii (Rz) between flours and starches, as determined by high-performance size exclusion chromatography (HPSEC) and multiple-angle laser light scattering (MALLS) (Park, I.; Ibanez, A. M.; Shoemaker, C. F. Starch 2007, 59, 69-77).

Stability of ingested methylcellulose in the rat determined by polymer molar mass measurements by light scattering.

Methylcellulose (MC) is ingested by humans in food and pharmaceutical formulations. The functional properties of MC like those of other linear polymers depend primarily on polymer length or molar mass for largely linear polymers. Although many studies in animals and humans have shown complete excretion of MC, in vitro human fecal fermentation studies indicate that MC can be degraded and presumably lose some of its functionality. In this study, MC polymer distribution in the feces from rats fed a diet containing 8% methylcellulose were compared to the fed MC. The water-soluble polymers in the feces were separated by a size exclusion chromatography (SEC) and the polymer distributions determined by multiple angle laser light scattering (MALLS). Detection of the fluorescent MC-calcofluor complex was used to confirm the identity of the eluting MC peak. All dietary MC was recovered in the feces. There is a small shift (P < 0.06) in the weight-averaged molecular weight of polymer distribution of MC extracted from the feces to 2.71 +/- 0.15 x 10(5) g/mol from 3.15 +/- 0.02 x 10(5) g/mol in the standard. There is also an increase in the polydispersity from 1.21 in the standard to 1.8 in the fecal extract. The distribution of the substituted methoxylated glucose monomers by gas chromatography also confirms the stability of MC fed to rats. The amount of actual hydrolysis is estimated to be about 0.1 glycosidic linkage/molecule. MC is not easily determined by standard dietary fiber methods, and SEC with MALLS and/or fluorescence may be a useful alternative.