Pleasantness in relation to difference threshold of NaCl in mashed potato

Difference threshold values for sodium chloride were determined to investigate to what extent just noticeable differences (jnd) affect preferences. Samples were unflavored, garlic-flavored and pepper-flavored mashed potato. At the reference concentration of 0.60% NaCl, the jnd value for unflavored and garlic-flavored samples was 0.07% NaCl, and for the pepper-flavored sample, 0.08% NaCl. The pleasantness of seven samples between ±9 jnds from the reference (0.60% NaCl), was rated on a graphic scale ranging from less pleasant to more pleasant (reference at the midpoint). Forty-one subjects participated in the test. For unflavored and garlic-flavored mashed potato, concentrations below 0.36% NaCl and above 0.82% NaCl, and for pepper-flavored, below 0.31% NaCl and above 0.83% NaCl, were required to obtain statistically significant differences in hedonic responses compared to the reference concentration.     

Digestibility in vitro of dry mashed potato products

The in vitro digestibilities of potato granules and flakes were compared. The digestibility of flakes was superior to that of granules. By drum-drying mashed potatoes, as is customary in the manufacture of flakes, the digestibility was improved, whereas by repeatedly drying and wetting mashed potatoes, as in the manufacture of potato granules, digestibility was diminished. The dry matter content of mashed potatoes obtained by rehydrating potato granules was higher than that of rehydrated flakes. The influence of digestibility and dry matter content of rehydrated potato granules and flakes on digestion in humans is discussed.     

马铃薯熟泥添加量对挂面品质的影响

为简化马铃薯挂面生产工艺,研究利用马铃薯熟泥代替水制作马铃薯小麦挂面,添加马铃薯熟泥(水分含量81.11%)从65 g到85 g至200 g小麦粉中,探讨马铃薯熟泥添加量对挂面品质的影响。结果表明:随着混合面团中熟泥的增加,马铃薯面条的煮熟增重率和烹调损失率均呈上升趋势;L*值降低,a*值、b*值升高;马铃薯小麦挂面的断裂距离先升高后降低,断裂强度、坚实度和剪切功均呈下降趋势。     

Pectin changes in the pre-cooking step of dehydrated mashed potato production

Some in-vivo and in-vitro characteristics of pectin methylesterase (PME) from cell wall and whole potato tuber were determined and its role was elucidated in the pre-cooking and cooling steps of commercial dehydrated mashed potato production. The isolated cell walls contained 16.3% anhydrogalacturonic acid with a degree of esterification (DE) of 56, and 25% of tuber total PME. Cell wall pre-cooking in model systems resulted in a DE of 53.2. Native cell wall pectin solubilisation was much less than that of H-cell walls devoid of metal cations. Calcium but not Mg, supplied as Ca(Mg)-starches, retarded pectin solubilisation, while Ca-uptake by retained pectin was high when cooling followed pre-cooking. Texture measurements of potato slices pre-cooked, cooled and cooked suggested a firming effect which could be attributed to Ca-release from gelatinised starch during pre-cooking, and stabilisation of Cabridges with free COO^? groups of cell wall pectin duringcooling. The role ascribed to PME in causing firming is de-emphasised.     

4D printing of mashed potato/purple sweet potato puree with spontaneous color change

In this study, the effects of pH (2.5, 6.5 and 7.8) and potato flake content (15%, 19%, 23% and 27%) on the properties of mashed potatoes (MP) were studied in terms of moisture distribution, rheological properties, texture properties and 3D printing performances. Results showed that the potato flake content was positively correlated with apparent viscosity, storage modulus (G′), and loss modulus (G″), while negatively correlated with tanδ and relaxation time (T₂). As the content of potato chips increased, the shape fidelity of MP increased after printing. The addition of citric acid increased MP's apparent viscosity, G′, hardness and gumminess, thus increasing its capacity to be self-supportable performance after deposition, while an opposite trend was observed when sodium bicarbonate was added. A dual-extrusion printer was furtherly used to manufacture a colorful 4D ready-to-eat food in terms of spontaneous color change by using anthocyanin-rich purple sweet potato puree and MP. Results indicated that the color change of MP was significantly correlated with the pH value and the potato flake content.Industrial relevanceThis work extends the conventional 3D printing of single material to multi-material, and potentially provides a new view on how to produce colorful food products by 4D printing in terms of spontaneous color change of 3D printed multi-material products.     

Effective use of nisin to control Bacillus and Clostridium spoilage of a pasteurized mashed potato product

Heat-resistant spore-forming bacteria such as Bacillus and Clostridium can survive and grow in cooked potato products. This situation represents both a public health problem and an economic problem. The natural food preservative nisin is used in heat-treated foods to prevent the growth of such bacteria. A cocktail of Clostridium sporogenes and Clostridium tyrobutyricum spores was inoculated into cooked mashed potatoes, which were vacuum packed, pasteurized, and incubated at 8 and 25 degrees C. The shelf life of the mashed potatoes at 25 degrees C was extended by at least 58 days with the addition 6.25 microg of nisin per g. At 8 degrees C, in control samples not containing nisin, the natural contaminant Bacillus grew, but the inoculated Clostridium strains did not until the temperature was raised to 20 degrees C after 39 days. No bacterial growth occurred in nisin-containing samples. The shelf life of the mashed potatoes was extended by at least 30 days with 6.25 microg of nisin per g. In trials involving a cocktail of Bacillus cereus and Bacillus subtilis strains, 6.25 microg of nisin per g extended the shelf life of mashed potato samples that were not vacuum packed by at least 27 days at 8 degrees C. At 25 degrees C, 25 microg of nisin per g extended shelf life by a similar period. Shelf life extension was also observed at lower nisin levels. Microbiological analysis of the mashed potato ingredients showed that a high spore level was associated with the onion powder. It is emphasized that the preservative and the ingredients must be well mixed to ensure good nisin efficacy. Nisin remained at effective levels after pasteurization, and good retention was observed throughout the shelf life of the mashed potatoes.     

Comparison of the consistencies of cooked mashed potato prepared from seven varieties of potatoes

Potato protein concentrates (PPC) were isolated from potato juice of seven studied varieties by thermal coagulation of 6.0–6.2 pH juices at 90–95 °C, followed by freeze-drying. Three levels of PPC were added to cooked mashed potato to raise the protein contents to 3, 4 and 5%, along with three levels of dry potato to obtain similar dry matter contents in mashed potatoes after the additions. The consistency of cooked mashed potato was measured objectively by a “back extrusion cell” connected to an Instron 1140 texturometer. Studied varieties differed in their consistencies of cooked mashed potato which increased with the dry matter content and increased after applying additives: (PPC and dry cooked potato). In spite of the similar dry matter contents the hardness of cooked mashed potato was higher when the PPC was used as an additive than with the dry potato addition.     

The effect of sample temperature on instrumental and sensory properties of mashed potato products

The effect of sample temperature on texture, firmness and the sensory attributes of fresh and frozen/thawed natural and commercial mashed potatoes was studied. Scanning electron microscopy was used to obtain information on the structure of potato cells and how this is affected by processing. Various parameters were measured and were found to increase at 55 °C, these changes could be related to gelatinisation of the starch remaining in the products. In natural mashed potato, texture profile analysis (TPA) and firmness parameters were lower in the processed than in the fresh samples, indicating a weakening of the structure; this was confirmed by photomicrographs. In commercial mashed potato, TPA parameters measured at 55 and 65 °C and firmness parameters measured at 25 °C were higher in the processed samples, indicating enhanced structural strength; this was confirmed by photomicrographs. Firmness per gram of product was the best instrumental parameter for measuring texture in these products. The results of the different analyses indicated that 55 °C was the preferred temperature for consumption of mashed potatoes.     

Soaking in a NaCl solution produce paler potato chips

Pairs of potato slices were blanched, soaked in a NaCl solution or water and fried. The originally adjoining faces of the chips were analysed for average L^*a^*b^* color by digital photography and image analysis.Stepwise increases in blanching temperature (60, 65, 70, 75, 80 °C/5 min) gave rise to gradually darker chips above 65 °C, by a total of 9L^* units (P=0.001). Slices soaked after blanching in a 3% NaCl solution for 5 min were consistently paler by 5L^* units (P=0.0054) than those soaked in water only.Change in the concentration range 0.6-9% NaCl was found using one-tailed paired t-test, subsequent to blanching at 70 °C/5 min (P=0.0125).     

Factors dominating adhesion of NaCl onto potato chips

ABSTRACT:  In this study, the adhesion factors examined were time between frying and coating, surface oil content, chip temperature, oil composition, NaCl size, NaCl shape, and electrostatic coating. Three different surface oil content potato chips, high, low, and no, were produced. Oils used were soybean, olive, corn, peanut, and coconut. After frying, chips were coated immediately, after 1 d, and after 1 mo. NaCl crystals of 5 different particle sizes (24.7, 123, 259, 291, and 388 μm) were coated both electrostatically and nonelectrostatically. Adhesion of cubic, dendritic, and flake crystals was examined. Chips were coated at different temperatures. Chips with high surface oil had the highest adhesion of salt, making surface oil content the most important factor. Decreasing chip temperature decreased surface oil and adhesion. Increasing time between frying and coating reduced adhesion for low surface oil chips, but did not affect high and no surface oil chips. Changing oil composition did not affect adhesion. Increasing salt size decreased adhesion. Salt size had a greater effect on chips with lower surface oil content. When there were significant differences, cubic crystals gave the best adhesion followed by flake crystals then dendritic crystals. For high and low surface oil chips, electrostatic coating did not change adhesion of small size crystals but decreased adhesion of large salts. For no surface oil content chips, electrostatic coating improved adhesion for small salt sizes but did not affect adhesion of large crystals.     

Influence of variety,site and storage on physical,sensory and compositional aspects of mashed potato

Over two seasons, eight potato varieties were grown locally and the three principal UK maincrop varieties at different sites. After periods of storage domestically prepared mashed potato was made from this material and assessed for back extrusion, adhesion, particle and cell size and distribution, ‘free’ starch, dry matter and cell wall polysaccharides in conjunction with sensory textural assessments for mealiness, moisture and structure. The results indicate that there are strong correlations between the physical measurements of work done during back extrusion (EWD) and the deformation to peak adhesion force (ADP) with both dry matter (DM) and the mean sensory scores for mealiness, moisture and structure. The sensory characteristics were also highly interdependent. The r value of these relationships declines after prolonged storage. No significant correlations were found between particle size or cell size and distribution and any of the physical, sensory or compositional data at any storage time. With the three principal UK maincrop varieties, site influenced DM and hence physical and sensory texture more strongly than variety.     

Physicochemical properties of potato and cassava starches and their mutants in relation to their structural properties

Physicochemical properties [swelling power (SP), pasting behaviour and retrogradation] of five wild type (wt), five amylose free (amf), four high-amylose (ha) potato starches (ps) and one wt and amf cassava starch (cs) were investigated. While swelling of wtps occurred in two phases, amfps showed a very fast swelling and no gel of swollen granules was observed at higher temperatures (>90 °C). Haps underwent only restricted swelling. SP of cassava starches were lower than those of potato starches. Wtps leached mainly amylose (AM) during heating at low temperatures. Molecules of higher molecular weight (MW) leached out at higher temperatures. Longer amylopectin (AP) chains [degree of polymerisation (DP) > 18] inhibited swelling while short chains (DP < 14) favoured swelling. Starch pasting behaviour of 5.0 and 8.0% starch suspensions was studied using Rapid Visco Analyser (RVA). For 5.0% suspensions, increased levels of high-MW AP and decreased levels of AM molecules led to higher peak viscosity. Longer AP chains (DP > 18) depressed peak viscosity, while short chains (DP < 14) increased peak viscosity for both concentrations. At 8.0%, peak viscosity increased with starch granule size. After 1 day of storage of gelatinised starch suspensions, wtps and especially amfps showed only limited AP retrogradation. In contrast, the high enthalpies of retrograded AP (ΔH_retro) and peak and conclusion temperatures of retrogradation (T_p,retro and T_c,retro) of haps suggested partial cocrystallisation between AM and AP. Chains with DP 18–25 seemed to be more liable to AP retrogradation. Wtcs and amfcs did not retrograde at room temperature.     

Determination of absolute threshold and just noticeable difference in the sensory perception of pungency

Absolute threshold and just noticeable difference (JND) were determined for the perception of pungency using chili pepper in aqueous solutions. Absolute threshold and JND were determined using 2 alternative forced-choice sensory tests tests. High-performance liquid chromatography technique was used to determine capsaicinoids concentration in samples used for sensory analysis. Sensory absolute threshold was 0.050 mg capsaicinoids/kg sample. Five JND values were determined using 5 reference solutions with different capsaicinoids concentration. JND values changed proportionally as capsaicinoids concentration of the reference sample solutions changed. Weber fraction remained stable for the first 4 reference capsaicinoid solutions (0.05, 0.11, 0.13, and 0.17 mg/kg) but changed when the most concentrated reference capsaicinoids solution was used (0.23 mg/kg). Quantification limit for instrumental analysis was 1.512 mg/kg capsaicinoids. Sensory methods employed in this study proved to be more sensitive than instrumental methods. Practical Application: A better understanding of the process involved in the sensory perception of pungency is currently required because "hot" foods are becoming more popular in western cuisine. Absolute thresholds and differential thresholds are useful tools in the formulation and development of new food products. These parameters may help in defining how much chili pepper is required in a formulated product to ensure a perceptible level of pungency, as well as in deciding how much more chili pepper is required in a product to produce a perceptible increase in its pungency.     

Textural character of sweet potato root of Korean cultivars in relation to chemical constituents and their properties

A relationship between chemical constituents and physicochemical and textural properties of different Korean sweet potato (SP) cultivars were investigated in terms of the hardness of raw and cooked root, alcohol insoluble solid (AIS), starch and amylose content, amylase activities, and pasting properties. Correlation coefficients were analyzed and principal component analysis was performed. The hardness of cooked root was found to correlate with the hardness ratio of cooked/raw SP, AIS content (0.75**), starch content (0.64**), and peak viscosity of SP powder (0.56*). It was discovered that SP cultivars could be classified into mealy (Sincheonmi, Daeyumi, Sinyulmi), intermediate (Dahomi, Sinjami, Geonhwangmi, Yeonjami, Pungwonmi), and waxy (Juhwangmi, Sinhwangmi) types depending on the first principal component (PC1, 68%). Therefore, it was found that the texture types of SP cultivars could be predicted from hardness of cooked root and are in relation to AIS and starch contents, and peak viscosity of raw powder.     

Electric field distribution in relation to cell membrane electroporation in potato tuber tissue studied by magnetic resonance techniques

Magnetic resonance electrical impedance tomography (MREIT) enables determination of electric field distribution during electroporation in which cell membrane permeability is increased by application of an external high electric field. In this study, MREIT was performed for the first time to predict electroporated areas in a pulsed electric field (PEF) treated vegetable tissue. The study was performed on potato tubers using different amplitudes of electric pulses and results were evaluated also by means of multiparametric MRI. MREIT determined regions of electric field distribution corresponded to visible darkened areas of the treated potatoes, as well to the results of multiparametric MRI. Results of this study suggest that MREIT could be used as an efficient tool for improving the effectiveness of PEF treatment applications.Industrial relevanceThis study presents a method capable of determining electric field distribution during PEF treatment using magnetic resonance electrical impedance tomography. The method has a practical value as it can potentially enable monitoring of the outcome of PEF applications which strongly depends on local electric field. Measurement of electric field distribution would enable detection of insufficient electric field coverage before the end of the PEF treatment, thus increasing and assuring its effectiveness.     

Lipids of potato tubers. II. Lipid-degrading enzymes in different varieties of potato tuber

The levels of two lipid-degrading enzymes, namely a hydrolytic enzyme (lipolytic acyl hydrolase) and an oxidising enzyme (lipoxygenase) were measured in tubers from 23 varieties of potato at harvest. Twenty-two varieties had very high levels of the hydrolytic enzyme, ranging from 5 to 50 jumol of substrate hydrolysed/ min/g of fresh weight of tuber. One variety, Desiree, contained a much lower level of this enzyme (0.06 to 0.2 units/g fresh weight). All varieties contained high levels of lipoxygenase activity in the range of 1 to 25 μmol of 0₂ consumed/min/g fresh weight of tuber, with linoleic acid as substrate. The combined action of these enzymes in the degradation of potato tuber lipids is discussed.     

层状氢氧化镁铝对碘离子的吸附性能

研究了层状氢氧化镁铝对水溶液中碘离子的吸附性能,考察了吸附时间、吸附剂加入量、碘离子初始浓度及pH值对吸附性能的影响,发现当吸附时间为7h,吸附剂加量大于2.4g/L,pH值在6.0～9.0之间时,吸附效果最好.     

Yield and quality of early potato cultivars in relation to the use of glufosinate‐ammonium as desiccant

BACKGROUND: Glufosinate‐ammonium (GA) is used for chemical vine killing of potato crop before harvest. Over two years we tested the effect of GA, applied at 0.48 kg ha^?1 of active ingredient, on desiccation of haulms, yield and some qualitative traits of tubers of three cultivars of early potatoes, a typical crop of southern Italy and large areas of the Mediterranean countries. RESULTS: Seven days after treatment desiccation reached 90% of leaves for all cultivars. At harvest, the highest desiccation percentage of haulms was 85% in Spunta. The desiccant did not affect yield in either year during which the analysis was carried out, but it increased the percentage of tubers in the range of 35–70 mm in diameter. In the first year, the treatment decreased dry matter and vitamin C content and increased free sugar concentration in tubers. In the second year, no negative effects on the nutritional traits were observed. Strong differences were found on yield and quality between the two years as a result of the different climatic conditions. CONCLUSION: In the two experiments GA had no influence on yield, but increased the percentage of potato tubers in the 35–70 mm range. From a qualitative standpoint in 2004 the chemical vine‐killing treatment had some negative effects (decreased dry matter and vitamin C content, increased free sugar concentrations), whereas no such negative effects were observed in 2005. Copyright © 2009 Society of Chemical Industry     

甜菜种质资源耐盐性筛选

利用0、100mM、200mM、300mM、400mM浓度的NaCl处理两份血缘关系较远的甜菜二倍体材料,结果表明:068(代号1)材料芽期耐盐性较强,自300mM始对甜菜种子发芽具有明显的抑制作用;抗1(代号2)材料耐盐性较弱,自200mM始对甜菜种子发芽具有明显的抑制作用,且用400mM处理的病芽率也达极显著水平.利用甜菜对盐敏感临界浓度300 mM对14份二倍体材料进行抗盐筛选,其中,代号1、3、8、12四份材料为抗盐胁迫种质,其它材料为盐胁迫敏感型种质.