The rise of the rhizosolenid diatoms

The 18S ribosomal DNA molecular phylogeny and lipid composition of over 120 marine diatoms showed that the capability to biosynthesize highly branched isoprenoid (HBI) alkenes is restricted to two specific phylogenetic clusters, which independently evolved in centric and pennate diatoms. The molecular record of C25 HBI chemical fossils in a large suite of well-dated marine sediments and petroleum revealed that the older cluster, composed of rhizosolenid diatoms, evolved 91.5 +/- 1.5 million years ago (Upper Turonian), enabling an accurate dating of the pace of diatom evolution that is unprecedented. The rapid rise of the rhizosolenid diatoms probably resulted from a major reorganization of the nutrient budget in the mid-Cretaceous oceans, triggered by plate tectonics.     

Rheological Properties of Starch‐Oil Composites with High Oil‐to‐Starch Ratios

Many applications have been developed for aqueous dispersions of jet‐cooked starch‐oil composites prepared by excess steam jet cooking. Previous formulations have typically contained 20–50% oil by weight based on the weight of starch. To expand the range of potential applications, new preparation methods were investigated to increase the oil content to as high as four times the weight of starch. High‐amylose corn starch was cooked in an excess‐steam jet cooker in the presence of oleic acid, and soybean oil was added to form the starch‐oil composites. Amylose is removed from solution by forming helical inclusion complexes with the oleic acid and, if the materials are cooled sufficiently quickly, the helical inclusion complexes only form small aggregates and shells around the oil droplets. Depending on the composition and preparation method, a wide range of stable, high‐oil materials from low‐viscosity liquids to smooth pastes can be formed. The flow, textural, and structural properties of these materials are shown. The materials can be used in a wide range of applications, including spray lubricants, lotions, and for fat delivery in cake mixes.     

Learning and Dietary Choice in Herbivores

Herbivores select diets from an array of plant species that vary in nutrients and plant secondary metabolites (PSM). The outcome is a diet higher in nutrients and lower in PSM than the average available in the environment. Food preferences in herbivores are controlled by dietary cues (i.e., flavor) associatively conditioned by the food's postingestive actions. The senses of smell, taste, and sight enable animals to discriminate among foods. Postingestive feedback calibrates sensory experiences—like or dislike—in accord with past and present experiences with a food's utility to the body. Thus, food selection can be viewed as the quest for substances in the external environment that provide a homeostatic benefit to the internal environment. Livestock form preferences for foods that supply needed nutrients and medicines and avoid foods that provide excesses of PSM and nutrients. In order to manifest this plasticity, animals need a variety of foods instead of being constrained to a single food or monoculture. Under natural conditions where diversity of plants is the rule, not the exception, eating a variety of foods is how animals meet their nutrient requirements and cope with—and likely benefit from—PSM in their diets. At certain doses, PSM may provide beneficial effects to herbivores and favor plant persistence and adaptability. If herbivores learn to utilize multiple plants, the costs of consuming PSM on animal production and well-being could be minimized and the benefits of PSM enhanced. Once individuals learn about the contextual benefits of consuming diverse foods, social models (e.g., mothers) could train new generations of herbivores by observational learning. We propose that by combining the concepts of animal learning and food diversity, it will be possible to create sustainable grazing systems with less dependence on fossil fuels and with enhanced benefits for soils, plants, herbivores, and people.     

Modeling temperature distribution in freshwater ponds

A model for predicting the vertical temperature profile of turbid freshwater ponds is described. High resolution in space and time and a reduction in the number of meteorological inputs usually required by such models is achieved by using pond surface temperature as a model input. A method to estimate hourly surface temperature is proposed and demonstrated.     

Determination of Rapid Visco Analyser Parameters in Rice by Near‐Infrared Spectroscopy

The objective of these studies was to find alternative Rapid Visco Analyser (RVA) viscoelastic parameters that are predictable by near‐infrared spectroscopy (NIRS). Currently, RVA instruments are widely used in assessing cooking and processing characteristics in rice. The ability to predict RVA parameters by NIRS would be useful in rapidly determining rice pasting qualities, but NIRS does not correlate with the traditional parameters (peak viscosity, final viscosity, breakdown, consistency, and setback). Alternative RVA parameters were sought by collecting RVA and NIRS data for a total of 86 short, medium, and long grain rice cultivars. The amylose contents were 0.41–24.90% (w/w) and protein concentrations were 8.47–11.35% (w/w). Partial least squares (PLS) regression models generated for the entire NIR spectrum against the RVA curve showed viscosity at 212–228 sec (80°C ± 1) varied linearly with NIR spectra (1,100 to ‐2,500 nm). Regression coefficient values were R = 0.961 for 212 sec and R = 0.903 for 228 sec. The PLS correlation coefficient for the prediction of amylose at 212–228 sec decreases along with the NIRS correlation to the same time frame. An opposite trend was observed for the correlation with protein at 212–228 sec. This comparison suggests the importance of amylose and protein in water absorption during this time frame.     

Use of Enzymes for the Separation of Protein from Rice Flour

When rice flour was treated with heat stable α-amylases, the effectiveness of protein separation increased with increased temperature. Depending on the enzyme, treatment at 90°C for 45 min resulted in protein contents of 47–65% for the insoluble fraction. Prior gelatinization enhanced the effectiveness of the enzyme reaction but was undesirable because the increased viscosity and gelation could cause difficulties in the processing operation. Follow-up treatment with other carbohydratehydrolyzing enzymes, such as glucoamylase, cellulase, and hemicellulase further increased the protein content up to 76% for the insoluble fraction. The subunit structure of the isolated proteins, based on electrophoretic analysis, remained practically unchanged after the treatment. The limited solubility and emulsion activity of rice protein were also unchanged.     

Light-Scattering Molecular Weights and Intrinsic Viscosities of Processed Waxy Maize Starches in 90% Dimethyl Sulfoxide and H2O

Waxy maize starch was treated by a variety of gentle and severe methods: direct dispersion-solubilization into 90% dimethyl sulfoxide (DMSO) and H₂O solvent, extrusion followed by dispersion-solubilization of the ground exudate into solvent, or jet-cooking or stirred autoclaving of an aqueous starch slurry followed by transfer into solvent. Intrinsic viscosities [η] and multiangle light-scattering measurements were made in 90% DMSO-H₂O. A Mark-Houwink relation, [η] = (0.28–1.2) M_w^{0.29 ± 0.04}, was obtained over a molecular weight range of ≈30–700 million. However, there was a large amount of scatter in the data when [η] were >140 mL/g. The power law relationship R_g ∝ M_w^0.41±0.04 was noted between radii of gyration and molecular weights. We infer from our data that over the entire range of M_w distributions, the amylopectin existed in solution as relatively compact molecules or aggregates and that in the higher molecular weight region, the size and possibly the shape of the “dissolved” amylopectin was highly sensitive to the method of dispersal and treatment.