Milk Plasmin Activity Influence on Cheddar Cheese Quality during Ripening

Up to six-fold increase in plasmin activity in milk did not significantly (p<0.05) affect the composition (moisture, protein, NaCl) of cheese, although a slight increase in moisture and decrease in protein content of the cheese was noted. Proteolysis in cheese increased with plasmin activity, resulting in improved flavor and overall quality of the cheese after 3 and 6 months ripening. Consistently, increasing the plasmin activity in milk about three-fold resulted in cheese of superior sensory quality.     

INFLUENCE OF ENZYMES ON THE TEXTURE OF BROWN PAN BREAD

Enzymes are commonly used to improve the textural quality of bread and to extend its shelf life. To study the effect of enzymes on the texture of brown pan bread, four types of bread were industrially manufactured using amylase, xylanase, a mixture of amylase : xylanase (1:1) and control (no enzyme). After baking, the bread samples were stored for 1, 4, 7, 10, 13, 15 and 17 days. At each storage time, bread texture was evaluated by sensory and instrumental methods, and the overall acceptability was determined. Instrumental and sensory texture data showed that the addition of amylase or amylase : xylanase decreased the staling rate of breads. Furthermore, the use of a mixture of amylase and xylanase provided better results than the addition of amylase alone. Therefore, the results suggest that the addition of a mixture of amylase and xylanase is recommended to extend the shelf life of brown pan bread. On the other hand, the addition of xylanase resulted in an increase of the staling rate. The results suggest that when xylanase is used to improve dough machinability, the addition of amylase along with it should be considered in order to prevent an increase of staling rate.     

MUSCLE AND ROE LIPID COMPOSITION IN DIPLOID AND TRIPLOID SCALLOPS

The use of triploid bivalves is now common in the market. We tested if there was a difference in lipid and long-chain highly unsaturated fatty acid (HUFA) accumulation in the muscle of diploid and triploid scallops ( Argopecten ventricosus ) during maturation, as triploids do not reproduce and lipids are not transferred to the gonad, and thus, could be accumulated in the meat (adductor muscle). Differences in triacylglycerols, phospholipids, esterified and free sterols, as well as HUFA in the reserves of gonads were found between diploid and triploid scallops. In contrast, no differences were found in the muscle for any of the lipid classes or fatty acid content in relation to ploidy, although they varied in relation to the sampling month.

PRACTICAL APPLICATIONS

The results obtained indicate that for human consumption purposes, the quality of the meat and roe of scallops follows a temporal pattern of lipid accumulation, with higher levels of total sterols in summer, but a higher proportion of arachidonic acid in winter and lower docosahexaenoic acid in autumn, and that the muscle lipid composition is not affected by the triploid condition.     

THE EFFECT OF CASEINOMACROPEPTIDE AND WHEY PROTEIN CONCENTRATE ON STREPTOCOCCUS MUTANS ADHESION TO POLYSTYRENE SURFACES AND CELL AGGREGATION

Caseinomacropeptide (CMP) from bovine, ovine and caprine milk and whey protein concentrate (WPC) were both evaluated for adhesion inhibition of Streptococcus mutans to polystyrene surface and cell aggregation. Adhesion inhibition by the CMPs and WPC at 1 mg/mL was higher than 84%. The CMPs and WPC caused aggregation of S. mutans cells at low concentrations. These findings suggest the application of these milk derived proteins as potential dental caries inhibitors and for possible food application uses.     

Cryo‐scanning x‐ray diffraction microscopy of frozen‐hydrated yeast

We developed cryo‐scanning x‐ray diffraction microscopy, utilizing hard x‐ray ptychography at cryogenic temperature, for the noninvasive, high‐resolution imaging of wet, extended biological samples and report its first frozen‐hydrated imaging. Utilizing phase contrast at hard x‐rays, cryo‐scanning x‐ray diffraction microscopy provides the penetration power suitable for thick samples while retaining sensitivity to minute density changes within unstained samples. It is dose‐efficient and further minimizes radiation damage by keeping the wet samples at cryogenic temperature. We demonstrate these capabilities in two dimensions by imaging unstained frozen‐hydrated budding yeast cells, achieving a spatial resolution of 85 nm with a phase sensitivity of 0.0053 radians. The current work presents the feasibility of cryo‐scanning x‐ray diffraction microscopy for quantitative, high‐resolution imaging of unmodified biological samples extending to tens of micrometres.     

ROLE OF WATER IN THE KINETIC MODELING OF METHANOL TRANSFORMATION INTO HYDROCARBONS ON HZSM-5 ZEOLITE

The attenuating effect of reaction-medium water (feed and/or reaction product) on the kinetics of the steps of methanol transformation into hydrocarbons on a HZSM-5 zeolite catalyst was studied by means of a kinetic model. In this model, the effect of water was quantified in all the steps of the kinetic scheme by means of a kinetic parameter, which is constant with temperature under the conditions of the MTG process. At low temperature, under conditions in which only methanol dehydration occurs, the kinetics of this reaction is attenuated by the presence of water, and the coefficient that quantifies the attenuation decreases as temperature is increased. In addition to considering the effect of water content in the reaction medium, another innovation of the kinetic model proposed, compared to those proposed in the literature consisting of lumps, is the fact that the higher reactivity of dimethyl ether over methanol is taken into account. A step of cracking of gasoline lump hydrocarbons to produce light olefins (ethene and propene) was also taken into account. The kinetic model proposed was verified by using the results obtained in an integral isothermal fixed bed reactor, in the 573–723 K range, for an ample range of space time values. The results revealed that the effect of water is due to its adsorption on the active sites by competition with the intermediate compounds of the kinetic scheme.     

EFFECT OF CHEMICAL INTERESTERIFICATION ON PHYSICOCHEMICAL PROPERTIES AND INDUSTRIAL APPLICATIONS OF CANOLA OIL AND FULLY HYDROGENATED COTTONSEED OIL BLENDS

Blends of canola oil (CO) and fully hydrogenated cottonseed oil (FHCSO), with 20, 25, 30, 35 and 40% FHCSO (w/w) were interesterified under the following conditions: 0.4% sodium methoxide, 500 rpm stirring, 100C, 20 min. The original and interesterified blends were examined for triacylglycerol composition, melting point, solid fat content (SFC) and consistency. Interesterification caused considerable rearrangement of triacylglycerol species, reduction of trisaturated triacylglycerol content and increase in disaturated-monounsaturated and monosaturated-diunsaturated triacylglycerols in all blends, resulting in lowering of respective melting points. The interesterified blends showed reduced SFC at all temperatures and more linear melting profiles if compared with the original blends. Consistency, expressed as yield value, significantly decreased after the reaction. Iso-solid curves indicated eutectic interactions for the original blends, which were eliminated after randomization. The 80:20, 75:25, 70:30 and 65:35 (w/w) CO: FHCSO interesterified blends showed characteristics which are appropriate for their application as soft margarines, spreads, fat for bakery/all-purpose shortenings, and icing shortenings, respectively.

PRACTICAL APPLICATIONS

Recently, a number of studies have suggested a direct relationship between trans isomers and increased risk of vascular disease. In response, many health organizations have recommended reducing consumption of foods containing trans fatty acids. In this connection, chemical interesterification has proven the main alternative for obtaining plastic fats that have low trans isomer content or are even trans isomer free. This work proposes to evaluate the chemical interesterification of binary blends of canola oil and fully hydrogenated cottonseed oil and the specific potential application of these interesterified blends in food products.     

An assessment of the texture of acidified sodium caseinate gels with added inulin using response surface methodology

This work evaluated the effect of inulin concentration (0–6.0% w/w) on the mechanical properties and microstructure of gels composed of sodium caseinate (CN) (1.5–6.5% w/w) at pH 4.6. Inulin did not statistically affect the elastic modulus and rupture properties of the studied gels but affected the nonlinear mechanical behaviour. Samples with higher inulin concentrations (6% w/w) presented strain‐weakening deformation behaviour, whilst gels with lower inulin concentrations were strain hardening. The presence of inulin resulted in a more closed‐pores network. Gel deformability increased as CN concentration was enhanced, reaching a maximum of 0.60 at 5.58% (w/w) CN, but was not affected by inulin concentration.