湿热处理辅助酶法制备大米多孔淀粉及其性质研究

以大米淀粉为原料,采用湿热处理辅助酶法制备多孔淀粉,通过单因素实验优化了湿热处理淀粉的工艺条件,并测定比容积、溶解率、膨胀率和吸油率等指标;通过X-晶体射线衍射、傅里叶红外光谱、扫描电镜和粒度分析仪对淀粉的结构进行表征,结果表明:最佳湿热工艺条件为含水量30％、处理时间6h、处理温度110℃,多孔淀粉的比容积、溶解度、...     

Changes in physicochemical and organoleptic properties of traditional Iranian cheese Lighvan during ripening

Lighvan cheese was studied to determine the physicochemical and biochemical changes over 90 days of ripening in brine. Acidity, pH, dry matter, fat values, lipolysis level, water‐soluble nitrogen (WSN), total nitrogen (TN), ripening index (RI), trichloroacetic acid‐soluble nitrogen (TCA‐SN) and organoleptic assessments were analysed. Dry matter and fat values decreased during ripening. Lipolysis level, RI, TCA‐SN values and salt content increased continuously until the end of the ripening period, but total nitrogen decreased throughout a 90‐day storage period. The ripening stage was the main factor affecting the cheese’s sensory properties.     

Effects of different batter formulations on the quality of deep-fat-fried carrot slices

The effects of batter coating containing pregelatinized tapioca starch or maltodextrin at different concentrations (1, 3 or 5%) on product quality of deep-fat-fried carrot slices were evaluated. Coated slices were fried for 2, 3 and 4 min at 170 °C. Coating pickup of batter formulations and moisture and oil contents, porosity, texture and colour of fried slices were determined. Batter without pregelatinized starch or maltodextrin addition was used as the control. Addition of 5% pregelatinized tapioca starch to the batter formulation provided the crispiest product with the lowest oil content. Increasing maltodextrin concentrations enhanced the crispness and colour development of the fried product but had an adverse effect on porosity, moisture and oil contents of carrot slices.     

Effects of pulsed electric field on colloidal properties and storage stability of carrot juice

The effects of pulsed electric fields (PEF) and high‐temperature short time (HTST) on the colloidal properties of carrot juice initially after PEF processing and throughout storage period were studied. Compared with HTST treatments, PEF treatments have less effect on the colloidal properties, such as cloud stability, zeta potential, viscosity and particle size distribution (PSD). Pectin methyl esterase (PME) could influence the colloidal properties of carrot juice by de‐esterification of the pectin. In the present work, PME activity was reduced significantly as electric‐field strength (from 15 to 30 kV cm^?1) and treatment time (from 100 to 800 μs) increased. The results also showed that the emergency of a new peak in PSD of samples occurred when the electric intensity exceeded 30 kV cm^?1. Images of transmission electron microscopy showed that particles slightly gathered after PEF treatment. However, under HTST treated, these smaller particles aggregated into net‐like structures that further gathered larger particles. At the micro level, both PEF treated (30 kV cm^?1, 800μs) and HTST treated kept good stability for more than 1 month.     

Changes in the physical properties of honey powder during storage

Honey powders produced by spray drying with the addition of Arabic gum and sodium caseinate were characterised in terms of the influence of storage time on the following physical properties: particle size, moisture content, water activity, bulk density, flowability and hygroscopicity. The storage affected those properties; after 12 weeks of storage, particle size decreased (except Arabic gum powder treated as a control sample), moisture content and water activity increased, hygroscopicity decreased. Changes in bulk density, particle size and moisture content caused the rise of Hausner ratio value; however, the powders were still characterised by a very good flow properties and low cohesiveness. The colour of reconstituted powders was also affected by storage; in most of samples, the darkening, reduction in redness and yellowness were observed. Colour parameters were the most stable in powders obtained with the addition of 2% w/w of sodium caseinate.     

Effect of adding ascorbic acid and glucose on the antioxidative properties during storage of dried carrot

In this study, carrots were treated with ascorbic acid (0.1%) in a glucose (1.0%) solution (AA-Glu), and then freeze-dried and hot-air-dried to investigate the effects on their antioxidant content after 30 days of storage. The antioxidant components were extracted from the carrot samples using methanol. To assess antioxidative properties, tests measured the samples’ reducing power, α,α-diphenyl-β-picrylhydrazyl (DPPH) radical scavenging activity, and ferrous ion chelating power. The above antioxidative properties of carrot extracts were compared with α-tocopherol and butylated hydroxyanisole (BHA). The analysis of antioxidant compounds included the total amount of ascorbic acid, total amount of phenolics, total amount of flavonoids, and carotenoids. The analysis showed that the samples immersed in AA-Glu solution prior to drying exhibited a higher antioxidative property than those not immersed.     

The effect of adding herbs to labneh on physicochemical and organoleptic quality during storage

The aim of this study was to investigate the influence of different herbs on physicochemical and organoleptic quality of labneh during storage. Analyses were carried out at 10‐day intervals in a storage period of 30 days. There were to significant differences in dry matter, fat and ash contents of the labneh samples. The pH and titratable acidity values were influenced by herbs and storage periods. Adding herb to labneh altered the colour: L* values in all samples decreased, whereas a* and b* values were affected differently from herbs added. Calcium content of the labneh decreased with the addition of herbs, but phosphorus, iron, copper and zinc contents increased. The sensorial scores of the labneh samples were influenced by the variety of herb added and the storage times. Addition of dill and parsley to labneh resulted in the greatest sensory scores.     

Comparative study: Thermal and non-thermal treatment on enzyme deactivation and selected quality attributes of fresh carrot juice

The combined effect of emerging electro-technology high-voltage cold plasma (HVCP) and non-thermal ultra-high hydrostatic pressure (UHP) as bioprocess technologies on the quality and stability of carrot juice has been evaluated. Carrot juice was treated with HVCP (70 kV for 3 min), UHP (300, 400, and 500 MPa) at 25 °C for 5 min, and a blanched sample of 100 °C for 5 min (BS) was also prepared. As compared to control and single treatments, the combined treatment (HVCP-UHP500) has attained better results in terms of enzyme inactivation and electroporation extraction of coloring compounds, phytochemicals, and ascorbic acid. Wherein, the maximum of 25.87 ± 0.12^a µg/100 mL of β-Carotene, 11.89 ± 0.80^a GAE (µg g⁻¹) of total phenols, and 24.07 ± 0.12^b mg/100 mL of ascorbic acid content in carrot juice were also observed in the combined treatment at 500 MPa. In addition, phytochemical enhancement might be attributed to the disintegration of phenolic dimers into simple aglycones, predominantly because of the electro-kinetic phenomenon of HVCP, which is subsequently intensified by UHP treatment. Therefore, the current study suggests that the combination of two novel techniques is a highly efficient method in terms of energy, time, and cost, with low yield efficiency and bio-safety.     

Effects of thermosonication and orange by‐products extracts on quality attributes of carrot (Daucus carota) juice during storage

Effect of thermosonication on carrot juice containing peel (CJPL) and pulp (CJPP) extracts from orange at different concentration (0.5, 2.0 and 4.0 mg GAE per g extracts) of total phenolic contents (TPC) was evaluated for quality attributes. Thermosonication of juice was done at 52 °C, 6 min for CJPL and 60 °C, 5 min for CJPP (values based on our preliminary optimisation results of ultrasound process conditions of the juice) at 40 kHz and 110W. Effect of thermosonication and addition of peel and pulp extracts at highest concentration increased the TPC and antioxidant activity of the juice (P < 0.05). Highest inactivation of microorganisms and better sensory attributes was achieved in thermosonicated CJPP for 21 days. Titratable acidity, pH, browning index and viscosity were improved by thermosonication and at highest extract concentration. °Brix and total carotenoid were not significantly affected by treatments. Therefore, thermosonication at 60 °C and 4.0 mg GAE per g extract concentration of peel and pulp may be used in formulation of functional carrot juice with improved health properties.     

Effect of hydrothermal treatment and pH on the formation of aglycones in soybean

This study aims to investigate the effect of hydrothermal treatment at different pH values on the formation of aglycones in soybean grains and flour. Thermal degradation of the aglycones was also examined after the baking of cakes at 175 and 210 °C for 35 min. The results showed that the hydrothermal treatment, when applied at pH 6.0 and 7.5, at 50 °C, favored the formation of aglycones in the soybean flour, in relation to the soybean grain. Under the baking conditions, loss of aglycones reached up to 70%.     

Comparative study of physical and sensory properties of pre-treated potato slices during vacuum and atmospheric frying

The objective of this research was to study the effect of different processing conditions on physical and sensory properties of potato chips. Potato slices of Desirée and Panda varieties (diameter: 30 mm; thickness: 3 mm) were pre-treated in the following ways: (i) control or unblanched slices without pre-drying; (ii) blanched slices in hot water at 85 °C for 3.5 min and air-dried at 60 °C until a final moisture content of ∼0.6 kg water/kg dry solid; (iii) control slices soaked in a 3.5 kg/m³ sodium metabisulphite solution at 20 °C for 3 min and pH adjusted to 3. Pre-treated slices were fried at 120 and 140 °C under vacuum conditions (5.37 kPa, absolute pressure) and under atmospheric pressure until they reached a final moisture content of ∼1.8 kg water/100 kg (wet basis). An experimental design (3 × 2³) was used to analyze the effect of pre-treatment, potato variety, type of frying and frying temperature over the following responses: oil content, instrumental color and texture and sensory evaluation. Vacuum frying increased significantly (p < 0.05) oil content and decreased instrumental color and textural parameters. Sensory attributes, flavor quality and overall quality, were significantly improved using vacuum frying. The higher frying temperature (140 °C) increased ΔE, maximum breaking force, hardness and crispness and decreased L^* and b^* values. On the other hand, Panda potato variety improved the color of the product. A great improvement on color parameters was obtained using sulphited potato slices instead of the other pre-treatments. Although, the better flavor was obtained for control potato chips, no significant differences were found for overall quality between control and sulphited potato chips. Significant correlations (p < 0.01) between sensory and instrumental responses were found.     

A mathematical model to describe the change in moisture distribution in maize starch during hydrothermal treatment

Instantaneous Controlled Pressure Drop, ' Détente Instantanée Contrôlée ' (DIC) was performed on standard maize starch at residual moisture content (∼12%). Changes in moisture distribution were observed during the treatment and modelled through a phenomenological model based on gravimetric data. The model proposes an exponential variation in the moisture content with processing time at various pressures. The predicted data were found to be in good agreement with experimental data. The values of water activity coefficient ( γ ) obtained from the model decrease, when processing pressure increases; 5.86, 3.71 and 3.36 (dry basis)⁻¹ for 1, 2 and 3 bar, respectively. The mass transfer coefficient decreases, when the pressure increases. Its value ranged from 5.89 × 10⁻⁵ m s⁻¹ for 1 bar down to 0.92 × 10⁻⁵ m s⁻¹ for 2 bar and 0.77 × 10⁻⁵ m s⁻¹ for 3 bar. This coefficient is not only controlled by a simple resistance to the mass transfer, but also by gelatinisation phenomenon that progresses when temperature increases.     

Impact of polylactic acid packaging on the organoleptic and physicochemical properties of tvarog during storage

The influence of polylactic acid (PLA) relative to polyamide/polyethylene (PA/PE) packing material on selected physicochemical attributes of acid curd cheese (ACC) (tvarog) packed in modified atmosphere (90% N₂/10% CO₂) and stored for 3 weeks at 5 ± 1°C was analysed. Three variants of tvarog were produced: (i) one packed in PLA film, (ii) one stored in metalised PLA film and (iii) tvarog packed in PA/PE film. The cheeses were assessed organoleptically. Changes in water and fat contents, titratable acidity, pH, water activity and fat oxidation were measured. Moreover, cheese hardness was determined by means of a double compression test (TPA). ACCs had the appropriate organoleptic attributes and the proper chemical compositions. The type of wrapping film highly significantly differentiated the samples regarding chemical composition, titratable acidity, pH and hardness. The films inhibited fat oxidation, but they did not inhibit transformation of fatty acids into conjugated diene and triene structures. Moreover, the samples differed in the course of changes in lipid extractability and in water activity.     

Barrier and optical properties of edible hydroxypropyl methylcellulose coatings containing surfactants applied to fresh cut carrot slices

Coatings made from hydroxypropyl methylcellulose (HPMC) containing surfactant mixtures of sorbitan monostearate (SPAN 60) and sucrose palmitate (sucrose ester P-1570) in aqueous and hydroalcoholic media were developed to analyse the effect of the hydrocolloid/surfactant ratio (H/S), the hydrophilic–lipophilic balance (HLB) of the surfactant mixtures and the solvent type used as dispersing media on the water vapour barrier properties of the films and their optical effect when applied to carrot slices. The results showed that the solvent type, H/S ratio and HLB significantly affected viscosity, surface tension, and stability (particle size and flocculation rate) of the film-forming dispersions, which in turn had a great influence on the extensibility and final film structure of the coating on the carrot surface. All these aspects affected the water vapour barrier properties of the film. The best water vapour barrier properties were found in the coating made from hydroalcoholic dispersions with intermediate values of the surfactant's HLB. The colour of coated carrot slices was mainly affected by the solvent dispersion media, the induced changes being greater for aqueous dispersions.     

Antioxidant activity of carrot juice in gamma irradiated beef sausage during refrigerated and frozen storage

The antioxidant activity of carrot juice in gamma irradiated beef sausage was studied. Four batches of beef sausage were prepared, in which the first batch was formulated with water as the control. The other batches were formulated with unconcentrated carrot juice, carrot juice concentrated by 35% and 60%, respectively. Samples were irradiated at doses of 0, 3 and 4.5 kGy. Then the extent of oxidation in raw sausages was determined during refrigerated and frozen storage through the determination of peroxide value (PV) and thiobarbituric acid reactive substances (TBARS) for lipid oxidation and carbonyl content for protein oxidation. The raw sausages were sensory evaluated during storage for colour, appearance and odour, while the grilled samples were sensory evaluated for their colour, odour, taste, texture and juiciness post-treatment only. Irradiation and storage significantly increased the PV, TBARS and carbonyl content in the samples formulated with water. The carrot juice significantly decreased the oxidative processes in the samples proportionally to the juice’s concentration. Furthermore, the sausages that were formulated with carrot juice had a high acceptable sensory scores as compared with the control samples.     

盐酸处理对谷朊粉理化性质改良的研究

利用盐酸处理改善谷朊粉的溶解度、乳化性、起泡性等理化性质,研究盐酸与谷朊粉的相对浓度、反应温度、反应时间、盐酸浓度对谷朊粉理化性质的影响。结果表明,盐酸处理改良谷朊粉理化性质的最佳条件:谷朊粉质量百分比为8%,盐酸∶谷朊粉为3.5∶100(质量比),反应温度65℃。试验证明,盐酸处理对谷朊粉的溶解度、乳化性及其稳定性、起泡性及其稳定性都有显著作用。     

蒸汽热处理对奥克榄物理力学性能的影响

对奥克榄进行120℃蒸汽热处理,比较了物理力学性能。结果表明：蒸汽热处理后奥克榄材色无明显变化,含水率、密度降低。干缩率和湿胀率明显下降,木材尺寸稳定性明显提高,抗胀（缩）率（ASE）达22%。木材主要力学性能略有升高。这说明蒸汽热处理在提高奥克榄尺寸稳定性的同时,不会降低木材的材色美观度及力学性能。     

油炸过程中淡水小龙虾理化性质与品质变化

研究分析油炸工艺（油炸温度（140、160、180、200 ℃）和油炸时间（15、30、45、60 s））对淡水小龙虾（虾壳、虾肉、虾黄）理化性质及品质的影响。测定淡水小龙虾中心温度、油炸损失率、色泽、质构特性、挥发性盐基氮（total volatile basic nitrogen,TVB-N）含量、硫代巴比妥酸反应物（thiobarbituric acid reactive substances,TBARs）值以及菌落总数（total plate count,TPC）的变化。结果表明：油炸温度对虾肉中心温度影响不显著,而油炸时间对虾肉中心温度影响显著（P＜0.05）;油炸温度180 ℃、油炸45 s时,虾肉中心温度可达到肌肉熟制标准温度;随着油炸温度升高及油炸时间延长,小龙虾油炸损失率显著上升（P＜0.05）;虾壳、虾肉、虾黄亮度值、红度值均呈上升趋势,而黄度值呈下降趋势;虾肉硬度、回复性、弹性、黏性、咀嚼性均显著增加（P＜0.05）;油炸过程中,虾肉TVB-N含量显著增加（P＜0.05）,但均低于10 mg/100 g,表明虾肉油炸后保持较好的新鲜度;虾肉TBARs值随油炸温度升高、油炸时间延长而增加,其中油炸时间对TBARs值影响较明显;新鲜虾肉初始带菌量非常高,油炸处理后虾肉TPC显著降低（P＜0.05）,油炸时间对虾肉TPC影响不明显。