THE INFLUENCE OF FAT, ACID, AND SALT ON THE TEMPORAL PERCEPTION OF FIRMNESS, SALTINESS, AND SOURNESS OF CHEESE ANALOGS

Eight cheese analogs varying in fat (10 and 25%), sodium chloride (0.5 and 2.0%), and citric acid (0.1 and 1.2%) were evaluated utilizing a time-intensity (T-I) procedure. Raising the salt content increased all T-I parameters for saltiness and resulted in higher maximum intensity (MAX), longer total duration (DUR) and larger area under the T-I curve (AREA) for sourness and firmness. Raising the acid content increased all T-I parameters for sourness and MAX and AREA for firmness. A higher fat content resulted in softer but more sour cheese analog (by all T-I parameters). For samples with low levels of acid or salt, sourness and saltiness MAX was reached during the 20s mastication interval. In contrast, for samples with high levels of salt or acid, MAX was attained after 20 s, but before expectoration at 30 s. As fat content increased from 10 to 25%, the cheese analogs were broken down more readily, the firmness duration decreased from 24 to 18 s.     

In-vitro development of corneal epithelial cells on a new hydrogel for epikeratoplasty

This study demonstrates the adhesion and growth of bovine corneal epithelial cells on the surface of a new hydrogel. The hydrogel, containing 78% of water and 22% of AN-69 polymer (poly(acrylonitrile-sodium methallyle sulfonate)), was obtained by phase inversion of polymer–dimethylformamide solution in physiological saline (0.9% NaCl). Experiments were also carried out using hydrogel treated with arginine, human albumin and collagen IV. Covering of hydrogel samples by epithelial cells was completed within ten days, with good cell viability. The epithelial cells spread out and formed a consistent cell layer, confirmed by immunocytochemistry experiments against cytokeratins. Transmission electron micrographs showed numerous desmosomes between cells and the presence of some membrane differentiations at the cell/hydrogel interface. This study suggests therefore that the hydrogel might be suitable for the development of artificial epikeratoplasty grafts.     

THE INFLUENCE OF FAT, ACID, AND SALT ON THE PERCEPTION OF SELECTED TASTE AND TEXTURE ATTRIBUTES OF CHEESE ANALOGS: A SCALAR STUDY

Twelve cheese analogs varying in amounts of fat (10 17.5, and 25%), sodium chloride (0.5 and 2.0%), and citric acid (0.1 and 1.2%) were prepared to determine the influence of the three constituents on taste and texture perception, as well as on the rheological behavior of the analogs. Sourness, saltiness, springiness, firmness, cohesiveness, and adhesiveness were rated by trained judges on a graphic scale. The Instron Universal Testing Machine was used for the rheological studies. Increasing the salt content in the cheese analogs resulted in an increased saltiness and sourness intensity and a decreased pH. Increasing the acid or salt content caused a significant decrease in cohesiveness and springiness and an increase in firmness. A higher fat content resulted in a softer, less springy, more cohesive and adhesive cheese analog.     

KNOWLEDGE ACQUISITION TECHNIQUES AND SECOND-GENERATION EXPERT SYSTEMS

We present techniques used in ADELE, a second-generation expert system (SGES), to support the knowledge acquisition activity in the diagnostic domain. The approach has been studied inside the framework of SGES; it is based on the reunions between knowledge acquisition and explanations. When new heuristic knowledge is acquired, its justifications are looked for in domain models to support the knowledge acquisition process. ADELE is a medical diagnostic reasoning system for electromyography.     

ANTIOXIDANT ACTIVITY OF FERMENTED BERRY JUICES AND THEIR EFFECTS ON NITRIC OXIDE AND TUMOR NECROSIS FACTOR-ALPHA PRODUCTION IN MACROPHAGES 264.7 GAMMA NO(–) CELL LINE

Serratia vaccinii, a novel bacterium isolated from blueberry microflora, increased the phenolic content of berry juices, and thus increased antioxidant activities. The fermentation capacity of Serratia was investigated with Saskatoon berries, cranberries, strawberries and grapes in both aerobic and anaerobic conditions. It was shown to be compatible with wine yeast in anaerobic fermentations, producing wine with high antioxidant activity. The effects of fermented berry juices were tested on lipopolysaccharide/inferon‐gamma‐activated macrophages 264.7 NO(–). Data indicated that fermented berry juices strongly inhibited activated‐macrophage NO production but induced tumor necrosis factor‐alpha production.     

The Sequence of a 54·7 kb Fragment of Yeast Chromosome XV Reveals the Presence of Two tRNAs and 24 New Open Reading Frames

A 54 719 bp fragment from the right arm of Saccharomyces cerevisiae chromosome XV has been sequenced from the inserts of two cosmids (pEOA213 and pEOA217). The computer analysis of this sequence has revealed the presence of eight known genes (CKA2, CYC1, ALG8, TCM1, TMP1, UFE1, RTS2 and ASE1) and four open reading frames (ORFs) with strong homologies with known yeast genes (MLP1, SIS2 and HBS1 and the allantoin permease). The characteristics of the other ORFs and of the corresponding proteins do not allow postulation of a precise function. Several have features reminiscent of cytoskeleton or motor elements (keratin-like, myosin-like) and several others have characteristics of proteins which interact with DNA (extremely basic, b-Zip structure and/or acidic domains). Two tRNAs (tRNA^Lys and tRNA^Pro) have also been identified on this fragment. Many of these ORFs present similarities with ORFs located on chromosome XI, indicating some information reshuffling between the two chromosomal fragments. The sequence has been deposited in the EMBL library data bank under Accession Number Z70678. © 1997 John Wiley & Sons, Ltd.     

当今世界，工程师拥有相似的薪酬与关切

"这是最美好的时代,这是最糟糕的时代."查尔斯·狄更斯的经典语录用来形容去年工程师的职业境遇是再贴切不过的了.     

CHARACTERIZATION AND INACTIVATION BY THERMAL AND PRESSURE PROCESSING OF STRAWBERRY (FRAGARIA ANANASSA) POLYPHENOL OXIDASE: A KINETIC STUDY

Polyphenol oxidase (PPO) was isolated from strawberries (Fragaria ananassa) and some of its biochemical characteristics were studied. The optimum pH for strawberry PPO activity was pH = 5.0. K_mand V_maxvalues were 5.95 mm and 133.8 A_420nm/min using a 50 mm catechol substrate solution. Kinetic studies showed that the thermal inactivation of strawberry PPO followed biphasic kinetics, resulting in an activation energy of 314.1 kJ/mol for the labile fraction and 321.3 kJ/mol for the stable fraction. Pressure/temperature inactivation of the stable fraction of strawberry PPO can be adequately described by a first‐order model. Pressure and temperature were found to act synergistically, except in the high temperature–low pressure region where an antagonistic effect was observed. A second‐degree polynomial model was successfully applied to describe the temperature/pressure dependence of the inactivation rate constants of the stable strawberry PPO fraction.     

THERMAL AND HIGH PRESSURE INACTIVATION KINETICS OF VICTORIA GRAPE POLYPHENOL OXIDASE: FROM MODEL SYSTEMS TO GRAPE MUST

Polyphenol oxidase (PPO) was extracted from white grapes (var. Victoria, South Africa) and partially purified by ammonium sulfate precipitation. Detailed kinetic studies on thermal and high‐pressure inactivation of grape PPO were preformed in McIlvaine buffer (pH = 4.0), in reconstituted grape must and in grape must. Thermal inactivation of PPO in McIlvaine buffer followed a first‐order model while in reconstituted grape must and grape must a biphasic inactivation behavior has been observed. Under all conditions investigated, a first‐order kinetic model could describe the pressure inactivation data. It was found that PPO is more thermostable and pressure‐stable in must than in reconstituted grape must and McIlvaine buffer at the same pH = 4.0.