Effect of high pressure processing on wheat dough and bread characteristics

Microbial, physical and structural changes in high pressured wheat dough were studied as a function of pressure level (50-250 MPa) and holding time (1-4 min). Thereafter, selected conditions of high hydrostatic processing (HPP) were applied to bread dough and the technological quality of the obtained breads was studied. The effect of HPP on wheat dough was investigated by determining microbial population (total aerobic mesophilic bacteria, moulds and yeasts), color and mechanical and texture surface related dough parameters (cohesiveness, adhesiveness, hardness and stickiness). HPP reduced the endogenous microbial population of wheat dough from 10⁴ colony forming units/g (CFU) to levels of 10² CFU. HPP treatment significantly (P < 0.05) increased dough hardness and adhesiveness, whereas treatment time reduced its stickiness. Scanning electron micrographs suggested that proteins were affected when subjected to pressure levels higher than 50 MPa, but starch modification required higher pressure levels. HPP treated yeasted doughs led to wheat breads with different appearance and technological characteristics; crumb acquired brownish color and heterogeneous cell gas distribution with increased hardness due to new crumb structure. This study suggests that high hydrostatic processing in the range 50-200 MPa could be an alternative technique for obtaining novel textured cereal based products.     

优质烤鸭面皮加工工艺的研究

研究了优质烤鸭面皮的加工工艺.通过对高低筋面粉比、揉面时间、烘烤时间和添加剂添加量等对烤鸭面皮品质有所影响的因素的研究,获得了最佳加工工艺与添加剂配方.最佳生产工艺条件为:高低筋面粉比1:1,揉面时间6min,烘烤时间10;正交实验确定的最佳添加剂配方为:添加荆添加量分别为0.4%单甘酯、0.5%谷朊粉、0.3%磷酸盐和0.3%海藻酸钠,且经过对比证明,其效果优于单独添加各添加剂的最优水平.本文旨在解决当前烤鸭面皮产品存在的表皮粗糙、色泽灰暗、蒸煮后复水性差、易老化等问题,为其品质的进一步改进提供参考.     

原料对酥皮面团加工品质和成品品质的影响

为研究基础原料对酥皮面团加工品质及成品品质的影响,以苏式月饼为例,用感官评定法和质构测定法评价了使用不同原料及配比所制得酥皮面团的加工品质以及成品月饼的感官品质和硬度。结果表明:原料及其配比对酥皮面团的加工品质和成品品质均具有明显影响;当水油面团中面粉湿面筋含量为27.4%时,酥皮面团的加工品质较好且成品品质较高,对于油酥面团,面粉的湿面筋含量越低,酥皮面团的加工品质和成品品质越高;当水油面团中猪油含量为33%、开酥比例为1.5时,酥皮面团的加工品质较好且成品品质最高;但酥皮面团的加工品质和成品品质之间不具有明确的相关性。。     

不同工艺条件对热烫面团质构特性的影响

热烫面团在实际加工中多凭经验,缺乏科学工艺指导实验以面团抗拉伸力、拉伸时间以及抗穿刺力3个质构参数为指标,选择水温、加水量和加盐量为考察因素,通过单因素实验和正交实验分析表明,在水温85C、加水量为54c％、含盐量为1％条件下,制备的热烫面团具有良好的质构特性,可作为热烫面团加工的参考依据.     

不同工艺条件对热烫面团质构特性的影响

热烫面团在实际加工中多凭经验,缺乏科学工艺指导。实验以面团抗拉伸力、拉伸时间以及抗穿刺力3个质构参数为指标,选择水温、加水量和加盐量为考察因素,通过单因素实验和正交实验分析表明,在水温85℃、加水量为54%、含盐量为1%条件下,制备的热烫面团具有良好的质构特性,可作为热烫面团加工的参考依据。      

Effect of high pressure processing and cooking treatment on the quality of Atlantic salmon

The effect of high pressure treatment (HPP) (150 MPa and 300 MPa for 15 min) and cooking on quality of Atlantic salmon based on microbial activity, lipid oxidation, fatty acid profile, colour and texture during 6 days of storage was studied. High pressure and cooking significantly (p < 0.05) reduced microbial growth. The 300 MPa treatment and cooking showed higher L∗ and b∗ values but lower a∗ values for dark muscle compared to control and samples treated at 150 MPa. An increase in pressure resulted in an increase in hardness, gumminess and chewiness parameters, and a decrease in adhesiveness compared to control and cooked samples. Whereas cooking and 150 MPa led to similar oxidation development as control in dark muscle, the 300 MPa treatment effectively reduced the samples susceptibility to oxidation. Fatty acid profile of cooked Atlantic salmon dark muscle showed significantly (p < 0.05) lower amounts of total saturated, n−3 Polyunsaturated fatty acids (PUFA) and n−6 PUFA and significantly (p < 0.05) higher amounts of monoenes than HPP treated samples during the entire storage period. However, the most important finding of this study was that there was no significant (p > 0.05) difference between control and HPP treated samples in terms of total saturated, monoenes, n−3 PUFA and n−6 PUFA fatty acid profile. This demonstrates that HPP is a very mild process in terms of its effect on fatty acids.     

超高压技术在虾类保鲜与加工中的应用

本文通过对国内外利用超高压技术在虾类杀菌、钝化多酚氧化酶、消除过敏原、脱壳、提取虾青素以及对肌肉色泽、p H、水分含量、蛋白质、风味、质构和组织结构的影响等方面的研究进行阐述,深入分析其作用机制和应用前景,并提出今后研究的关键技术与发展方向,为超高压技术在虾类保鲜与加工中的产业化应用提供理论参考。      

超高压技术在虾类保鲜与加工中的应用

本文通过对国内外利用超高压技术在虾类杀菌、钝化多酚氧化酶、消除过敏原、脱壳、提取虾青素以及对肌肉色泽、p H、水分含量、蛋白质、风味、质构和组织结构的影响等方面的研究进行阐述,深入分析其作用机制和应用前景,并提出今后研究的关键技术与发展方向,为超高压技术在虾类保鲜与加工中的产业化应用提供理论参考。     

Effect of the addition of soluble (nutriose,inulin and polydextrose) and insoluble (bamboo,potato and pea) fibres on the quality of sugar‐snap cookies

Dietary fibre intake can help to improve the health of the population. Cookies are one of the most consumed bakery products. The aim of this study was to investigate the influence of different fibres on cookie quality. Soluble fibres (nutriose, inulin and polydextrose) decreased dough consistency favoured cookie spread during baking and produced wider and thinner cookies. In contrast, insoluble fibres (elongated and rounded) showed an opposite trend increasing dough consistency and giving rise to cookies with higher moisture, lower spread factor and higher hardness. Long insoluble fibres gave rise to harder cookies and with lower spread factor. Cookies made with soluble fibres were darker than the control cookie and cookies containing insoluble fibres. Therefore, solubility and shape of insoluble fibres play an important role in cookie quality. Fibre selection will be key to enriched cookies development.     

Effect of high hydrostatic pressure to sweet potato flour on dough properties and characteristics of sweet potato‐wheat bread

The effect of high hydrostatic pressure (HHP, 100–400 MPa) for 20 min at 25 °C to sweet potato flour (SPF) on dough properties and characteristics of sweet potato‐wheat bread was investigated. The particle size of SPF after HHP was decreased significantly. The obvious rupture was observed in granules of SPF after HHP at 300 and 400 MPa by scanning electron microscopy (SEM). After HHP, significant differences on endothermic peak temperatures (T_P) of SPF were observed by differential scanning calorimetric (DSC), of which the enthalpy change (ΔH) had a slight increase, expect that at 200 MPa. Gas retention of dough with SPF after HHP increased markedly from 1199 (0.1 MPa) to 1246 ml (100 MPa). Specific loaf volume of bread with SPF at 400 MPa was increased significantly, while the hardness and chewiness were reduced. Thus, SPF treated with HHP at 400 MPa could be potentially used in wheat bread production.     

Effects of high protease-activity flours and commercial proteases on cookie quality

The effects of high-protease activity flour (HPAF) on cookie quality were investigated comparing two proteases (Protease 1 and Protease 2). The commercial proteases and HPAF were added to wheat flours (cvs. Gerek and Gün) with different gluten quality at levels of comparable protease activity. Electrophoresis was used to determine the hydrolyzing effects of the proteases on gluten proteins. Cookies were prepared with wire-cut formulation and quality parameters (spread ratio and color values) were determined. Electrophoresis results showed that degradative effects of Protease 1 and Protease 2 were more evident on gliadins and glutenins, respectively. Protease 2, added to cookie formulations for both wheat samples, gave the highest spread ratios. For the strong wheat cultivar (Gün) spread ratio values of the cookies supplemented with HPAF were comparable to those supplemented with Protease 2.     

Effect of high pressure processing on yield,quality and storage stability of peanut paneer

Paneer was prepared from peanuts by soaking the nuts for 8 h followed by removal of skin, grinding, extraction of milk and coagulation using calcium sulphate (1% solution). In another method the peanut milk was high pressure processed at 600 MPa for 5 min before coagulation. The obtained paneer samples were vacuum packed and kept at refrigerated temperature (6 ± 1 °C) for storage and evaluated for physico‐chemical, sensory and microbial attributes. High pressure processing of milk before coagulation resulted in increase in paneer yield significantly (P < 0.05) as well as maintained the quality of the paneer to a better extent as compared to control during refrigerated storage for a period of 45 days.     

Effect of high pressure processing on the quality of acidified Granny Smith apple purée product

The aim of the present study was the evaluation of the physicochemical, nutritional and microbial quality of acidified Granny Smith (GS) apple purée processed on industrial-scale high pressure system during 3 weeks of refrigerated storage (5 °C ± 1 °C). Two commercially feasible pressure treatments (400 and 600 MPa/5 min/20 °C) and a mild conventional pasteurization at 75 °C/10 min, with pasteurization values of P_70°C^7.5 = 8.15 min, were conducted and their effect on total vitamin C (total Vit C), ascorbic acid (AA) and total phenolic content (TPP), and on instrumental quality parameters (color, viscosity, soluble solids, titratable acidity and pH) were comparatively studied. Inactivation of indigenous microorganisms (total aerobic mesophilic and psychrotrophic counts and moulds and yeasts) of the apple product was also studied and monitored during storage. Total Vit C and AA contents were unaffected by the 400 MPa and the mild pasteurization treatment. TPP content was not changed during processing at 400 MPa, but was affected by the 600 MPa and also slightly by the pasteurization treatment. Experimental data on the loss of total Vit C during storage were described with a first-order reaction kinetic and times of half loss between 9.3 to 10.3 days could be estimated for the three studied processes. Storage provoked loss of TPP content and color deterioration of pressurized GS puree samples, which was attributed to enzymatic browning reactions. Microbial counts were reduced by the different preservation techniques below the detection limit (50 cfu g^?1) and storage revealed no further growth.Industrial relevanceThis is one of the first studies applying commercial industrial-scale high pressure equipment for the pasteurization of an acidified apple purée product. The pressures of 400 and 600 MPa with 5 min holding time at ambient temperature render economically feasible processes with high throughput and productivity. In the European Union the most important fruits in terms of production are apples. Apple purée is a largely consumed preserve in many households and beside apple juice or cider is one of the most important apple products in the market. In contrast to traditional apple purée preparation, high pressure processing or mild thermal treatments could imply new opportunities for the apple processing industry in developing more fresh-like, value-added apple products with reasonable shelf life.     

Effect of cold pre‐treatment duration before freezing on frozen bread dough quality

The effect of cold pre‐treatment (CT) duration prior to freezing on the quality of a standard bread dough was investigated. Doughs held at 0 °C or 10 °C for 1 h or 3 h before air‐blast freezing were compared with standard dough frozen after 0.5 h at 0 °C (0 °C/0.5 h) and fresh (unfrozen) dough. Cumulative gas production measured in a risograph was used to quantify the dough quality after storage at ?18 ± 0.1 °C for 1, 7 or 17 days. Relative to fresh dough, gas production significantly reduced after freezing for all treatments. The doughs with CT at 0 °C for 1 or 3 h or 10 °C for 1 h had significantly higher gas production after freezing and less rapid decline in gas production during frozen storage than the doughs with the 0 °C/0.5 h CT. The 10 °C/3 h CT gave no gas production benefit after freezing and had the most rapid decline in gas production during frozen storage.