教学课程资源库 更多>>

关键词： Enriched yogurt   Rheological properties   Oxidative stability   Microbial analysis   Sensory evaluation  

摘要： This study investigated the qualitative properties of fortified yogurt produced with a sweet almond and sesame oil nanoemulsion as well as an emulsifier (0.25-0.5% Span 80 and Tween 80). The pH, acidity, syneresis, rheological properties, microbial composition, fatty acid composition, oxidative stability, antioxidant activity, and sensory properties of the fortified yogurt were investigated during 15 days of storage at 4 degrees C. The results showed pH and syneresis were reduced by the incorporation of sweet almond and sesame oil nanoemulsion containing 0.5% emulsifier, while the acidity, malondialdehyde formation, and antioxidant activity were increased. The use of the oil nanoemulsions exerted no significant effect on the Lactobacillus delbrueckii subsp. bulgaricus count but decreased the amount of Streptococcus salivarius subsp. thermophiles. By the addition of sesame and sweet almond oils, the yogurt viscosity decreased but the elastic modulus and viscous modulus values increased. Among the treated samples, the highest sensory score during 15 days of storage was related to the yogurt fortified with sesame oil. Overall, sesame oil with 0.25% of the emulsifier is suggested for the production of fortified yogurt.

摘要： Lines of various forms of stimulated scattering have been revealed in the scattering spectrum excited by pulsed second-harmonic radiation of a YAG:Nd3+ laser in an initially homogeneous aqueous colloidal solution (suspension) of polystyrene nanoballs. Dynamic light scattering measurements have shown that the laser-stimulated coagulation of some nanoballs with the formation of particles with an order-of-magnitude larger size occurs in the solution. An explanation of this phenomenon has been proposed.

关键词： Synthesis   Hydrazone   Thin films   Characterization   Optical properties   Energy conversion and storage  

摘要： We synthesized a novel isatin hydrazone derivative 3-(((E)-3-ethoxy-2-hydroxybenzylidene)hydrazineylidene) indolin-2-one (IL) via condensation of isatin hydrazide with 3-ethoxy-salicylaldehyde in methanol. Then ZnO was chelated with the ligand (IL) to produce a novel ZnOIL complex. The characteristics of the IL and ZnOIL compounds were compared using various techniques, including nuclear magnetic resonance, ultraviolet-visible, infrared, and mass spectroscopy, and elemental analyses to confirm their chemical compositions. The optical properties of the IL and ZnOIL thin films were studied based on spectroscopic measurements of their absorbance, transmittance, and reflectance within the range of 300-2500 nm. The optical constants, dielectric parameters, and dispersion energies were determined and interpreted. The electronic inter-band transitions of the IL and ZnOIL films were characterized by indirect allowed transitions. The value of the optical band gap (E-g) was determined as 2.14 eV for the IL film, but chelation of IL with ZnO decreased E-g to 2.02 eV. The surface and volume energy loss functions were lower for ZnOIL compared with IL. The structural and the optical features of ZnOIL may be tuned, and thus it is a promising candidate material for applications in energy conversion and storage devices.

关键词： acceptability   active packaging   additive   Passiflora edulis Sims   respiration  

摘要： To achieve a suitable packaging configuration, it is important first to determine the physicochemical characteristics related to the packaged product. In this study, the physicochemical characterization of fresh purple passion fruits of three different ripening stages was carried out to determine key variables for the packaging, such as O-2 consumption and CO2-ethylene production rates. Subsequently, intermediate-ripe fruits were packaged for 21 days at 6 degrees C under three packaging conditions: Xtend(R) perforated bags, low-density polyethylene (LDPE) bags, and LDPE bags with a novel ethylene scavenger active additive (ESAA). It was observed that an equilibrium modified atmosphere was formed in the packages. For the Xtend(R) bags, the highest values of O-2 (yo(2) = 0.184 to 0.192) and lowest of CO2 (yco(2) = 0.033 to 0.041) were reached, whereas for the LDPE bags with ESAA these values were moderate. In the case of ethylene, the LDPE bags showed the highest levels in the headspace (26 to 31 ppm), whereas the lowest levels were obtained in the LDPE bags with additive (2 to 4 ppm). These levels resulted in a delay in the ripening of the fruits during storage, which was verified through a sensory acceptability test that was carried out on the juice extracted from the fruits. In this sensory test, panelists identified similar characteristics between the fruits packaged with ESAA and the Xtend(R) bags, regarding the control fruits. The LDPE bags with the ethylene scavenger performed satisfactorily and can considerably delay the ripening, which may result in longer shelf life and conservation of fresh purple passion fruits. Practical Application This work presents a novel packaging proposal that reduces oxygen and ethylene levels in contact with purple passion fruits. Our proposed active packaging can be used to increase the fruit shelf life by improving its conservation conditions throughout the chain of storage, transport, and distribution in the market. With this,

关键词： Moisture  

摘要： In this study, the antioxidant and antimicrobial effects of carboxymethyl cellulose (CMC) enriched with Thymus vulgaris L. extract (TE) on physicochemical, microbial, and sensorial properties of fresh hazelnut were investigated. Hazelnuts treated with CMC coating solution (0.0, 0.5, and 1.5% wt/vol) containing TE (0.0, 0.5, and 1.0% vol/vol) and stored at ambient temperature for 147 days. The results showed that the uncoated sample had the highest mean moisture content (4.03%), yeast and mold count (2.63 Log cfu/g), and development of Aspergillus spp. (36.25%). The oxidation rate of coated hazelnut with 1.5% CMC and 1.0% TE was lower (PV = 0.47 meq ***(-1), TBA = 0.02 mg ***(-1), and FFA = 0.40%) than that of uncoated sample (PV = 1.07 meq ***(-1), TBA = 0.04 mg ***(-1), and FFA = 0.76%). According to the results of an instrumental mechanical and sensory evaluation, 0.5% CMC and 0.5% TE is an optimal coating to extend shelf life and promote the nutritional value of hazelnut. Practical applications The enhancement of characteristics of fresh hazelnut during storage should be a major concern for the industry and market. It could be admirable to have hazelnut that is well preserved for as long as possible. Consequently, to convince long shelf life and to expand protection from rancidity processes and microbial growth, the nuts have to be preserved, instantly after harvest. Carboxymethyl cellulose (CMC) is a natural, abundant, unexpansive biodegradable biopolymer, and is a possible material for edible coating applications. In this study, the use of TE as a natural preservative adds nutritional value to the hazelnut and contributed to a shelf life extension of fresh hazelnut. Furthermore, CMC containing TE with its barrier properties vis-a-vis moisture, and oxygen, allows less expensive synthetic materials to be used, prevents loss of flavor, and serves as a suitable carrier for various additives.

关键词： Dates   Physico-chemical properties   Thin-layer solar drying  

摘要： Determination of the drying curves characteristics of date fruits at tamar (fully ripe) stage of Khalas and Ruzeiz varieties by using two constructed solar dryers namely;direct solar dryer (DSD) and indirect solar dryer (ISD), Modelling of drying curves data of date fruits for both varieties and solar dryers, and the effect of solar drying process on four physico-chemical properties of the date fruits for both varieties and solar dryers were investigated. The four physico-chemical properties included linear dimensions of length and width, mass, colour L, a, and b values and pH. The two solar dryers were constructed from local materials and were used in the date fruits drying. Study experiments were carried out at The Research and Training Station of King Faisal University, AlAhsa, KSA. Results for both varieties and solar dryers showed that Khalas date fruits dried more than Ruzeiz ones and date fruits drying took place predominantly in the falling rate period i.e. diffusion was the main physical mechanism governing moisture movement in date fruits. Page model was more accurate in predicting the measured drying curve data. Generally, under the present study solar drying conditions, some physico-chemical properties of mass and pH of date fruits were affected, while properties of linear dimensions (length and width) and colour L, a, and b values were not. This concluded that under similar drying conditions of the study some unit operations of date fruits processing such packaging, sorting and grading they will not be affected.

关键词： degree of polymerization   degree of substitution   photoirradiation   silver nanoparticles   sodium carboxymethylcellulose  

摘要： Silver nanoparticles (AgNPs) stabilized by sodium carboxymethylcellulose (Na-CMC) with degree of substitution (DS) 0.65-0.90 and degree of polymerization (DP) 200-600 were synthesized by photochemical method. The structural, physico-chemical, and physico-mechanical properties as well as antimicrobial activity of polymer films containing the Na-CMC and AgNPs were studied. The shape, quantity, and size of the AgNPs embedded into the Na-CMC films were determined by UV-Vis spectroscopy, ZETASIZER Nano ZS, atomic force microscopy and transmission electron microscopy. It was found that the increase of silver nitrate concentration in solution of Na-CMC followed by photoirradiation leads to the change of size and shape of AgNPs. The AgNPs in the range of size from 5 to 35 nm were found to enhance the microbicidal activities of the Na-CMC films.

关键词： Moisture  

摘要： The objectives of this research were to study the effect of concentration of egg white and air temperature on physicochemical properties and the effect of packaging on the moisture during storage of foam mat dried chili sauce powder. Results demonstrated that 6% (wt/wt chili sauce basis) egg white as foaming agent and drying temperature at 80 degrees C to produce chili sauce powder were the optimum condition that led to higher foam expansion, yield percentage, and water solubility, and lower moisture content, A(w), and bulk density. For microbiology test, total viable count, yeast and mold, coliform, and E. coli followed a Thai community product standard of seasoning powder. Plots of moisture content of product in all types of packaging versus time were linear model. The best packaging that could protect moisture permeability was aluminum foil laminate. According to the shelf life prediction, the product in packaging could be stored for 13 months. Practical applications Chili sauce (hot sauce) is one of the most famous products processed from chili and can be added to many kinds of foods. Application of foam mat drying for this product can extend its shelf life and increase product variety for consumers. The optimum condition for production of chili sauce powder is 6% egg white as foaming agent and drying temperature at 80 degrees C. The kinetic modeling can be applied for tracking moisture changes of products. The best packaging that could protect moisture permeability was aluminum foil laminate that can be used to store the product for 13 months. This research can be benefit the industrial sauce production for better distribution of the products.

关键词： Bacillus coagulans   physicochemical   rheological properties   volatile compounds  

摘要： Bacillus coagulans 13002 (13002) as a new potential starter was incorporated into the yoghurts for fermentation in this study. We compared three groups of yoghurt, including Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus (SL), 13002 (BCS), and 13002 and SL (BCS + SL). Compared with the combination of SL and BCS, the group of BCS + SL exhibited better flavour, higher titratable acidity, cohesiveness and richer volatile compounds, suggesting that the combination of BCS and SL was more efficient to produce the best sensory properties of yoghurt (P < 0.05). The production of volatile compounds in fermentation with and without the addition of BCS was mainly affected by aldehydes, ketones, esters and hydrocarbons, respectively. Furthermore, BCS additions into traditional starters resulted in increasing organic acids and speeding up the usage of sucrose and lactose during the fermentation period of yoghurt. Our study suggested that BCS is a favourable starter supplement for improving the quality of probiotic yoghurts.

关键词： Pyridone   Chromenopyridone   Anti-inflammatory   Antipyretic   Ulcerogenic   And physicochemical studies  

摘要： Throughout this study, we present the victorious synthesis of a novel class of 2(1H)-pyridone molecules, bearing a 4-hydroxyphenyl moiety through a one-pot reaction of 2-cyano-N-(4-hydroxyphenyl)acetamide with cyanoacetamide, acetylacetone or ethyl acetoacetate, and their corresponding aldehydes. In addition, the chromene moiety was introduced into the pyridine skeleton through the cyclization of the cyanoacetamide 2 with salicylaldehyde, followed by treatment with malononitrile, ethyl cyanoacetate, and cyanoacetamide, in order to improve their biological behaviour. Due to their anti-inflammatory, ulcerogenic, and antipyretic characters, the target molecules have undergone in-vitro and in-vivo examination, that display promising results. Moreover, in order to predict the physicochemical and ADME traits of all synthesized compounds and standard reference drugs, paracetamol and phenylbutazone, the in-silico prediction methodology was provided.