Andy Mauromoustakos

Subcritical Solvent Extraction of Procyanidins from Dried Red Grape Pomace

Procyanidins in dried Sunbelt ( Vitis labrusca L.) red grape pomace were extracted using accelerated solvent extraction (ASE) with pressure (6.8 MPa), one extraction cycle, and temperature (40, 60, 80, 100, 120, and 140 degrees C). Six ethanol/water solvents (0, 10, 30, 50, 70, and 90%, v/v) were compared to conventional extraction with acetone/water/acetic acid (70:29.5:0.5, v/v/v). Procyanidins in the extracts were identified by HPLC-ESI-MS/MS and contained degrees of polymerization (DP) of 1-5 (monomers through pentamers) and polymers (DP > 10). Generally, 50% ethanol/water (v/v) extracted more total procyanidins than other ethanol/water compositions, and contained up to 115% of total procyanidins extracted by the acetone-based conventional solvent. Additionally, 50% ethanol/water (v/v) extracted 205, 221, and 113% more epicatechin, catechin, and dimers, respectively, than conventional extraction. Results indicated greater extraction of low oligomeric procyanidins using 50% ethanol/water (v/v) solvent between 80 and 140 degrees C.

Glassy state transition and rice drying: development of a brown rice state diagram.

ABSTRACT The effect of moisture content (MC) on the glass transition temperature (Tg) of individual brown rice kernels of Bengal, a medium-grain cultivar, and Cypress, a long-grain cultivar, was studied. Three methods were investigated for measuring Tg: differential scanning calorimetry (DSC), thermomechanical analysis (TMA), and dynamic mechanical analysis (DMA). Among these methods, TMA was chosen, because it can also measure changes in the thermal volumetric coefficient (β) of the kernel during glass transition. TMA-measured Tg at similar MC levels for both cultivars were not significantly different and were combined to generate a brown rice state diagram. Individual kernel Tg for both cultivars increased from 22 to 58°C as MC decreased from 27 to 3% wb. Linear and sigmoid models were derived to relate Tg to MC. The linear model was sufficient to describe the property changes in the MC range encountered during rice drying. Mean β values across both cultivars in the rubbery state was 4.62 × 10-4/°C and ...

Jam Processing and Storage Effects on Blueberry Polyphenolics and Antioxidant Capacity

Fresh blueberries were processed into sugar and sugar-free jams and stored for 6 months at 4 and 25 degrees C. The jams were analyzed immediately after processing and over 6 months of storage for polyphenolic content, percent polymeric color, and antioxidant capacity. Processing resulted in losses of anthocyanins, procyanidins, chlorogenic acid, and ORAC in both jam types, but flavonols were well retained. Marked losses of anthocyanins and procyanidins occurred over 6 months of storage and were accompanied by increased polymeric color values. Chlorogenic acid levels also declined during storage, but flavonols and ORAC changed little. Jams stored at 4 degrees C retained higher levels of anthocyanins, procyanidins, and ORAC and had lower polymeric color values than jams stored at 25 degrees C. Sugar-free jams retained higher levels of anthocyanins and had lower polymeric color values than sugar jams late during storage. Blueberry jams should be refrigerated to better retain polyphenolics and antioxidant capacity.

Degree of milling effects on rice pasting properties

ABSTRACT The effects of degree of milling on pasting properties of medium-grain (cv. Bengal and Orion) and long-grain rice (cv. Cypress and Kaybonnet) were quantified using a Brabender ViscoAmylograph and a Rapid Visco Analyser. For all the cultivars tested, surface and total lipid contents decreased as the degree of milling increased. The peak viscosities for all rice increased with the degree of milling and the rates of increase were higher for medium-grain than long-grain cultivars. Degree of milling did not have a consistent effect on final viscosity for all the cultivars tested.

Carbon decomposition kinetics and nitrogen mineralization from corn, soybean, and wheat residues

Abstract An incubation study was conducted for 30 days in Taloka (fine, mixed, thermic mollic Albaqualf) and Leadvale (fine, silty, siliceous, thermic typic Fragiudult) silt loam soils to evaluate carbon (C) and nitrogen (N) mineralization from soybean [Glycine max (L.) Merr.], corn (Zea mays L.), and wheat (Triticum aestivum L.) residues. Corn and soybean residues were collected at the tasseling and late vegetative stages, respectively. Wheat straw was collected after harvest. Carbon dioxide (CO2) evolution and inorganic N accumulation were measured. Carbon mineralization was described by a sequential decomposition model with a rapid and slow phase, each described by first‐order kinetics. Rapid and slow fraction rate constants and percent rapid were determined. Decomposition ranged from 39% for wheat to 67% for soybean. Carbon dioxide evolution peaked on the third day, and 30 to 50% of residue C was decomposed during the first six days of incubation. Decomposition and N mineralization were higher in the ...

Effect of Moisture Content and Temperature on Respiration Rate of Rice

ABSTRACT One cause of yellowing or stackburn of rice may be elevated respiration rates caused by storage at either high moisture content (MC) or temperature. The effect of MC and temperature on the respiration rate of Oryza sativa L. ‘Bengal’ and ‘Cypress’ rice harvested in the fall of 1998 was investigated. For respiration rate measurement of rough rice at different temperatures, rice samples at high, medium, and low MC were sealed in quart jars and equilibrated to temperatures of 20–80°C. The respiration rate was quantified by measuring the rate of CO2 accumulation in the free air space. To determine the effect of MC on respiration rate, rough rice was tested at 12–25% MC. Respiration was greatly affected by MC and temperature. The response of respiration to temperature was dependent on MC and varied between rice cultivars. Respiration rates increased as MC increased from ≈15 to 25%. Maximum respiration was at 50°C when MC was high (20–25%). At 15% MC, respiration increased from 20 to 70°C, while respir...

Improved stability of chokeberry juice anthocyanins by β-cyclodextrin addition and refrigeration.

Chokeberry anthocyanins are susceptible to degradation during processing and storage of processed products. This study determined the effects of three pH levels (2.8, 3.2, and 3.6) and four β-cyclodextrin (BCD) concentrations (0, 0.5, 1, and 3%) alone and in combination on the stability of chokeberry juice anthocyanins before and after pasteurization and over 8 months of storage at 4 and 25 °C. Lowering the pH from 3.6 to 2.8 in the absence of BCD provided marginal protection against anthocyanin losses during processing and storage. Addition of 3% BCD at the natural chokeberry pH of 3.6 resulted in excellent protection of anthocyanins, with 81 and 95% retentions after 8 months of storage at 25 and 4 °C, respectively. The protective effect of BCD was lessened with concentrations <3% and reduction in pH, indicating changes in anthocyanin structure play an important role in BCD stabilization of anthocyanins.

Medicago truncatula (E)-β-ocimene synthase is induced by insect herbivory with corresponding increases in emission of volatile ocimene

Virtually all plants are able to recognize attack by herbivorous insects and release volatile organic compounds (VOC) in response. Terpenes are the most abundant and varied class of insect-induced VOC from plants. Four genes encoding putative terpene synthases (MtTps1, MtTps2, MtTps3 and MtTps4) were shown to accumulate in Medicago truncatula Gaertn. in response to Spodoptera exigua (Hübner) feeding and methyl jasmonate treatment in a previous study [S.K. Gomez, M.M. Cox, J.C. Bede, K.K. Inoue, H.T. Alborn, J.H. Tumlinson, K.L. Korth, Lepidopteran herbivory and oral factors induce transcripts encoding novel terpene synthases in Medicago truncatula, Arch. Insect Biochem. Physiol. 58 (2005) 114-127.] The focus of the current study is the functional characterization of one (MtTps4) of these four genes. Using an M. truncatula cDNA clone, the insect-inducible putative terpene synthase was expressed in Escherichiacoli and shown to convert geranyl diphosphate (GPP) into the monoterpene (E)-beta-ocimene as the major product. The clone was therefore designated M. truncatula (E)-beta-ocimene synthase (MtEBOS). Transcripts encoding this enzyme accumulate in M. truncatula leaves in response to exogenous jasmonic acid treatments, lepidopteran herbivory, and lepidopteran oral secretions. Treatment with the ethylene precursor, 1-aminocyclopropane-1-carboxylic acid (ACC) did not cause an increase in MtEBOS transcripts. The volatile (E)-beta-ocimene was released from leaves of both undamaged and insect-damaged plants, but at levels two-fold higher in insect-damaged M. truncatula. Although leaves have low constitutive levels of MtEBOS transcripts, RNA blot analysis indicates no constitutive expression in flowers, stems or roots. The strong insect-induced expression of this gene, and its correspondence with release of volatile ocimene, suggest that it plays an active role in indirect insect defenses in M. truncatula.

Relating rice milling quality changes during adsorption to individual kernel moisture content distribution

ABSTRACT Several varieties of rough rice that were either stored for an extended period of time or freshly harvested were conditioned to initial moisture contents ranging from 10 to 17%. After the individual kernel moisture content distributions were measured, the samples were soaked in water at temperatures ranging from 10 to 40°C. The samples were then dried and milled. The bulk critical moisture content, at which head rice yield began to decline due to moisture adsorption, ranged from 12.5 to 14.9%, depending on the variety, harvest moisture content, and storage conditions. The kernel critical moisture content, determined from each sample from the cumulative kernel moisture content frequency distribution, increased with increasing sample initial moisture content.

Prediction of Texture of Cooked White Rice by Near-Infrared Reflectance Analysis of Whole-Grain Milled Samples

ABSTRACT Although much work has been done using near-infrared (NIR) spectroscopy with rice, little is currently known about the effectiveness of NIR to predict functional attributes of rice such as cooked rice texture, especially as they are influenced by postharvest parameters. In this study, NIR spectroscopy was used for predicting cooked rice texture as affected by postharvest history. Cooked rice texture attributes were evaluated by a nine-member trained descriptive panel, and milled white rice was scanned using a near-infrared (NIR) spectrophotometer. Sensory attribute models were developed using partial least squares regression in combination with jack-knife, a model optimization method, using NIR reflectance spectra (400–2,500 nm) and 1st and 2nd derivatives. Cooked rice adhesion to lips (R2 = 0.88), hardness (R2 = 0.79), cohesiveness of mass (three chews) (R2 = 0.79), and toothpack (R2 = 0.85) were satisfactorily fitted (n = 201–202) using the 2nd derivative spectra. Other attributes evaluated, su...