Texture Of Potatoes Research Articles

KARAKTERISTIK SIFAT-SIFAT KIMIA DAN ORGANOLEPTIK KUE KERING BERBAHAN DASAR PATI SAGU, UBI KAYU, UBI JALAR DAN KELADI

The purpose of this research was to characterize chemical and sensory properties (color, texture, taste and liking) of starch-based sago, cassava, sweet potato and cocoyam cookies. Analysis of cookies include moisture content, ash, fat, protein, crude fiber and sensory analysis including color, texture, taste and likeness). The proximate composition indicated that the water content of cookies varied between 1.48 to 2.05%, ash content of 0.65 to 0.72%, 19.23 to 21.76% of fat, crude fiber from 0.41 to 0.71% and 1.33 to 2.42% of total protein. Based on organoleptic tests, the color of cookies was yellow to brownish-yellow, with crispy texture, the taste was sweet and were mostly preferred.

Evaluation of Quality Characteristics of Potato Slices during Drying by Infrared Radiation Heating Method under Vacuum

The effect of drying behaviour on the drying rate and quality characteristics of potato slices in a vacuum- infrared drying system was studied. In this work, the effect of the infrared radiation powers (100, 150, and 200 W) and vacuum levels (20, 80, 140 mmHg and atmosphere pressure) at different slice thickness (1, 2 and 3 mm) on drying rate and shrinkage percentage and rehydration capacity were investigated. From the study, it was concluded that IR power level has a significant effect on processing time and drying rate. With increasing radiation power, time drying is reduced and consequently drying rate is increased. The drying rate curve of potato slices at initial drying time is in the ascending phase because of surface moisture evaporation and after this phase due to the start of influence of water from within of material to surface descending phase occurs. Also, shrinkage percentage increased with increase of sample thickness. In other words, shrinkage was decreased at different thickness with an increase of infrared radiation power and vacuum level. It was discovered that the long period of drying and increase of sample thickness may have contributed to a decrease in rehydration capacity. Because of porous texture of potato, as soon put in boiling water for 3 minutes, the water absorption process quickly started and before the insert damage to product tissues, to maximum amount of water absorption will reach. The results also showed that with increasing shrinkage, rehydration capacity was decreased.

Effect of Frying Parameters on Mechanical Properties and Microstructure of Potato Disks

AbstractThe effect of frying temperature and time on surface pore characteristics, oil content, moisture loss and mechanical properties of potato disks is investigated. Scanning electron microscopy is used to study the surface pore characteristics and rheological behavior is investigated using a dynamic mechanical analyzer. Both frying temperature and frying time had a significant impact on the pore area, creep behavior, moisture loss and fat uptake of potato disks. The changes in pore area and creep compliance were dynamic and, in turn, affected the oil uptake and moisture loss rates. Average open pore area and percent open pore area increased to 1.15 μm2 and 14.04%, respectively, during the middle frying stages. Higher frying temperature resulted in faster structural degradation, moisture loss and oil uptake during initial frying stages. Higher frying times tended to increase the percentage open pore area.Practical ApplicationsThe article investigates structural and mechanical changes in potato disks during frying. These are crucial to understand the transport mechanisms during frying, and to study the role played by the product microstructure on both oil uptake and texture development. The creep compliance function reported in this article is useful for predicting the texture of potatoes via mathematical models describing the frying.

Effect of Ratio Oil to Potato on Amount of Oil uptake and Quality of Potato French Fries

In deep fat fried products health should be addressed to meet consumer demand .the soft and moist interior together with crispy crust are desirable characteristics of most fried food. In this study the effect of ratio oil to potato on amount of oil uptake of potato strips at two size were investigated. Results showed that ratio oil to potato 20:1 lead to increase in potato loss of strips during frying among other ratios (33% oil uptake %). Oil to potato 10:1 had the lowest amount of fat content (24% oil uptake %). By this study, the highest and lowest loss weight percent were 44% and 34% which related to ratio 20 and 10 respectively. Significant differences in texture of several ratio were observed. Ratio 20 was the most texture of fried potato, but from view of oil uptake %, ratio of 10 was the best for two sizes of french fries potato.

Effect of Ultrasound-Assisted Osmotic Dehydration as a Pretreatment on Deep Fat Frying of Potatoes

The objective of this study was to investigate the possibility of using ultrasound-assisted osmotic dehydration (UAOD) as a pretreatment prior to frying and to study its effects on the quality of fried potatoes. The quality parameters, moisture content, oil uptake, color, texture, and microstructure of fried potatoes, were chosen. Quality of fried potatoes treated with UAOD was also compared with the ones treated with osmotic dehydration (OD). Potato slabs (40 × 40 × 7 mm) were pretreated with different osmotic solutions (15 % sodium chloride and 15 % sodium chloride/50 % sucrose solutions) at different temperatures (25, 45, and 65 °C) with and without ultrasonic waves for different treatment times. The pretreatment conditions which are OD for 90 min and UAOD for 30 min using 15 % sodium chloride/50 % sucrose solution were applied prior to frying at 170 °C for 2, 4, and 6 min. UAOD reduced the oil content of fried potatoes by 12.5 % (db) as compared to untreated fried potatoes at the end of frying. There was no significant difference between OD and UAOD in reduction of oil uptake in fried potatoes. However, UAOD was found to have the advantage of improving the color of French fries. In addition, it shortened the pretreatment time of OD by about 67 %. Cell structure of fried potato was damaged in the presence of pretreatments of OD and UAOD.

Effect of Potato Orientation on Evaporation Front Propagation and Crust Thickness Evolution during Deep‐Fat Frying

The various theoretical approaches that have been proposed for modeling heat and mass transport during deep-fat frying of potatoes do not take into account the effect of potato orientation with respect to gravity. This can be partly attributed to lack of systematic experimental information at different orientations. The objective of the present work is to experimentally study the effect of potato orientation on the evaporation front propagation and crust thickness evolution and how this effect varies with frying conditions. To achieve this goal, a special device has been constructed which, among others, permits: (a) exposure of only one surface of a potato stick to hot oil, (b) rotation of this potato surface at 0°, 90°, and 180° with respect to gravity, and (c) accurate placement of miniature thermocouples under-but very close to-the exposed potato surface. Crust thickness is determined by 2 independent methods: (a) microphotography and (b) a micrometer. It is found that the evaporation front propagation and crust thickness evolution are different among the examined surface orientations. The fastest heat penetration and thickest crust are measured at vertical (90°) surfaces. The implications of this finding regarding potato texture and energy consumption are discussed. Understanding the role of surface orientation on the crust evolution and the propagation of the evaporation front inside the food is of particular value to: • Deterministic modeling efforts of the coupled heat and mass transfer phenomena during deep-fat frying, and • food industry; the present data suggest that crispier food is produced and less energy is consumed when the food is placed at a nonhorizontal position inside the fryer.

SENSORY ATTRIBUTES AND CONSUMER ACCEPTANCE OF SWEET POTATO CULTIVARS WITH VARYING FLESH COLORS

ABSTRACTThe sensory characteristics of sweet potatoes (n = 12 cultivars) with varying flesh color (orange, purple, yellow) and the impact of flesh colors on consumer acceptance were evaluated. A lexicon was developed for sweet potato flavor followed by consumer acceptance testing conducted with and without blindfold conditions to identify if color or visual cues impacted consumer acceptance. Cluster analysis was performed on overall liking scores followed by external preference mapping to identify the drivers of liking for sweet potatoes. The lexicon differentiated sweet potatoes. Appearance (visual appearance) positively impacted liking scores of products that were not well liked but had a lower impact on liking when the sweet potato was well liked suggesting that flavor and texture were the driving attributes for liking. Three consumer clusters were found for overall liking. All clusters liked smooth texture, brown sugar and dried apricot flavor and sweet taste and disliked bitter, umami, astringent mouthfeel, vanilla aroma and residual fibers. Clusters were differentiated by the liking of visual moistness and color homogeneity, white potato, canned carrot and dried apricot flavors, chalky, firmness, denseness and fibrous texture. Sweet potatoes with unfamiliar colors were accepted by all consumers but different sensory characteristics appealed to different consumer groups.PRACTICAL APPLICATIONSSweet potatoes (Ipomoea batata) are nutritious and have numerous health benefits. The orange‐fleshed cultivars are the most familiar to consumers, but other cultivars with varying flesh color have been identified. The sensory properties of these various sweet potatoes and the drivers of liking are not established. The development of a sensory lexicon for sweet potatoes allowed for characterization of sensory properties and assisted in the understanding of key consumer liking attributes for sweet potatoes. These results can assist sweet potato breeders or marketers in understanding the impact of color and the importance of flavor and texture of sweet potatoes for the consumer fresh market.

Parenchyma cell microstructure and textural characteristics of raw and cooked potatoes

► The texture of potatoes from different cultivars was found related to their microstructure. ► Raw tuber parenchyma with small cells and well integrated structure had harder and cohesive texture. ► Mealy cooked tubers with higher starch and dry matter had higher hardness and cohesiveness. ► TEM showed loosened cell wall microfibrils after cooking, showing lost cell wall integrity. Cooking, microstructural and textural characteristics from four New Zealand potato cultivars (Agria, Nadine, Moonlight, and Red Rascal) were studied. Potatoes from the waxy cultivar, Nadine, showed lowest dry matter and starch content and also had highest cooking time compared to the other cultivars. The total colour difference, Δ E , indicative of browning and darkening during storage (for 1 h) of the peeled potatoes was observed to be highest for Red Rascal, followed by Nadine and was lowest for Agria. Light (LM) and confocal scanning electron (CSLM) micrographs revealed Moonlight and Red Rascal raw potato parenchyma cellular structure to be well integrated, showing compact hexagonal cells. Raw tubers from these cultivars also exhibited higher hardness and cohesiveness, as observed using texture profile analysis (TPA). Moonlight potato parenchyma retained cell wall outline after cooking and its cells were observed to be completely filled with gelatinised starch matrix, whereas the cellular structure of Nadine potato parenchyma was completely disintegrated after cooking. TPA results of cooked potatoes agreed well with these microstructural observations, with Moonlight cooked potatoes showing highest cohesiveness and hardness. The cell wall of parenchyma cells was observed to degrade partially upon cooking of potatoes, resulting in loosening of the cell wall microfibrils, as observed using transmission electron microscopy (TEM) of a selected potato cultivar. Also, the cell wall decreased in thickness after cooking. The remains of the primary cell wall along with some electron dense granular structures were observed floating in the cytoplasmic starchy matrix in potato tuber parenchyma cells.

Potato tuber pectin structure is influenced by pectin methyl esterase activity and impacts on cooked potato texture

Although cooked potato tuber texture is an important trait that influences consumer preference, a detailed understanding of tuber textural properties at the molecular level is lacking. Previous work has identified tuber pectin methyl esterase activity (PME) as a potential factor impacting on textural properties. In this study, tuber PME isoform and gene expression profiles have been determined in potato germplasm with differing textural properties as assessed using an amended wedge fracture method and a sloughing assay, revealing major differences between the potato types. Differences in pectin structure between potato types with different textural properties were revealed using monoclonal antibodies specific for different pectic epitopes. Chemical analysis of tuber pectin clearly demonstrated that, in tubers containing a higher level of total PME activity, there was a reduced degree of methylation of cell wall pectin and consistently higher peak force and work done values during the fracture of cooked tuber samples, demonstrating the link between PME activity, the degree of methylation of cell wall pectin, and cooked tuber textural properties.

Changes in the Texture of Potatoes by Cooking

Changes in the Texture of Potatoes by Cooking

QUANTITATIVE DESCRIPTIVE SENSORY ANALYSIS OF FIVE DIFFERENT CULTIVARS OF SWEET POTATO TO DETERMINE SENSORY AND TEXTURAL PROFILES

ABSTRACT A trained sensory panel was used to establish terminology for describing the sensory attributes of different cultivars orange‐fleshed sweet potato (OFSP) and white‐fleshed sweet potato (WFSP). Quantitative descriptive analysis was applied to evaluate the samples in terms of the aroma, texture, flavor and aftertaste attributes. Thirteen attributes were identified. Principal component analysis (PCA) was applied to identify any factors differentiating between the sweet potato cultivars. The findings indicated that the main differences were, in PC1, the flavor and density and adhesive textural characteristics, and, in PC2, the grainy and firm textural characteristics of the different cultivars. OFSP displayed a more dense and pasty texture, which was most intense in the Resisto cultivar. W119 had a more grainy texture when compared with the other cultivars tested. WFSP was more moist and fibrous. Therefore, OFSP differed in color, was sweeter and displayed flavor characteristics of yellow vegetables (such as butternut and pumpkin) when compared with WFSP. PRACTICAL APPLICATIONSAlthough standard sensory evaluation techniques were used in this project, the materials used were sweet potatoes, which are of interest. Sweet potato is a root vegetable, and in this project, a lexicon for the textural properties, as well as a flavor profile of sweet potato, was developed. Such information can be used for sensory evaluation of other root vegetables. The shear force of the sweet potatoes was measured, and the methodology to determine shear forces and its contribution to the overall evaluation of the texture of sweet potatoes is included in the article. Furthermore, white‐fleshed sweet potatoes are commonly known, and the flavor of WFSP is compared with that of orange‐fleshed sweet potatoes.

METHODS TO ROUTINELY PREDICT THE TEXTURE QUALITY OF POTATOES BY TUBER SPECIFIC GRAVITY

ABSTRACT Information on texture of steam‐cooked potato is of increased importance for consumers of fresh potatoes. As potato texture not only depends on genetic disposition but also on growth conditions, simple and reliable methods are needed to improve characterization of single potato lots. In the present study 65 potato lots were fractionized to 192 tuber samples according to their specific gravity and used for sensory evaluations. The aim was: (1) to further clarify the role of tuber specific gravity, variety and growth condition for texture attributes; and (2) to develop statistical models to predict potato texture objectively and reliably. Texture attributes varied considerably within varieties. The attributes mealiness, dryness, graininess were closely interrelated. Within the varieties, the three attributes as well as sloughing correlated with specific gravity (r = 0.78–0.96). Thus, they were predicted by specific gravity using variety‐dependent models. Alternatively, using variety‐independent models mealiness was predicted by the two parameters specific gravity and sloughing. Softness was related to the variety, but not to specific gravity. The statistical models may be helpful in optimizing the allocation of individual potato lots to specific cooking types for the retail market and for processing.PRACTICAL APPLICATIONSInformation on texture of steam‐cooked potato is of increased importance for consumers of fresh potatoes. We were approached by the potato industry to develop simple and reliable methods for characterization of single potato lots in trade. The objective measurement of texture by instrumental methods is rarely performed for routine testing, probably because of the laborious procedures. The measurement of tuber specific gravity is very simple. However, the relationship between specific gravity and various texture attributes is still not clear. We elaborate the relationship in an extensive evaluation using a broad range of potato lots. The models presented here may be applied directly for routine testing. We also suggest adaptations for routine calibration of new varieties and for routine testing of single lots. Further, the study encourages the scale‐up of technologies which allow the grading of potatoes according to their specific gravity and thereby increase significantly texture homogeneity.

COMPRESSING BEHAVIOR AND TEXTURE EVALUATION FOR POTATOES PRETREATED BY PULSED ELECTRIC FIELD

ABSTRACT The objective of this study was to investigate the effects of pulsed electric field (PEF) treatment on compressing behavior and texture of potatoes. Textural data reveal that PEF treatment can cause enlargement of pressure for the same level of deformation. The fracture pressures Pc were approximately the same for both untreated and PEF‐treated specimens, Pc ≈ 4.5 ± 0.4 MPa. The maximal pressure Pm, at which the time of the pressure‐induced rupture of intact cells should be of the same order of magnitude as the time of fluid expression from damaged cells, was estimated as Pm ≈ 6 MPa. For a small pressure (P = 1 MPa) to obtain a similar deformation (ε = 0.15) requires pressing time t ≈ 3.5 h for untreated tissue and t ≈ 70 s for PEF‐treated tissue. Measured electrical conductivity was practically constant and exhibited no noticeable time dependence during constant pressure stage in untreated samples, while the conductivity of PEF‐treated specimens decreases in the course of pressing.PRACTICAL APPLICATIONSSolid–liquid expression is widely used in the food industry for the extraction of fruit and vegetables. Efficiency of this process can be increased by different pretreatment methods. Pulsed electric field (PEF) has been shown to be good for juice yield intensification and for improving the product quality in juice production. It is of great interest for process purposes to study texture proprieties of PEF‐treated and untreated tissues, because texture is one of the most important quality attributes of food products. This work also gives new information about the mechanism of the PEF‐induced damage and expression from tissues. The obtained results may be helpful for development of new engineering concepts based on PEF‐enhanced extraction at comparatively low pressures and moderate time of processing.

Porosity, Color, Texture, and Microscopic Structure of Russet Potatoes Dried Using Microwave Vacuum, Heated Air, and Freeze Drying

Microwave vacuum drying (MVD) provides an alternative drying method for making dried products with a puffed, porous texture. This article describes the porosity, color, texture, and microscopic analysis of potatoes dried using MVD, heated air (HAD), and freeze drying (FD). The porosity was calculated from a ratio of apparent density and true density. A mathematical model for calculating true density from moisture content and apparent density was derived. Potatoes dried using MVD had 20 times the porosity compared to HAD potatoes; but FD had the highest porosity. Puncture tests and SEM images supported indirect and direct confirmation for the experimental porosity. Texture measurements indicated that MVD potatoes were crispy and porous, HAD potatoes were hard and brittle, and FD potatoes were spongy and subject to shatter. MVD potatoes retained more fresh-like color compared to HAD and FD potatoes.

Effect of processing conditions on the water absorption and texture kinetics of potato

The effects of temperature, drying method and pre-drying treatments on water absorption and textural degradation of potatoes during soaking were examined. Samples were pre-dried in a convective oven (60 °C) or in a microwave oven (250, 440 or 600 W), and subsequently rehydrated in a water bath at temperatures between 20 and 80 °C. The texture of potatoes (firmness) was measured using a texture analyser. Fick’s Second Law of Diffusion was used to describe the rehydration kinetics (diffusion coefficient, D and equilibrium moisture content, X e). Textural degradation kinetics were estimated using the fractional conversion equation. The rehydration characteristics and textural degradation kinetics were dependent on temperature, pre-blanching, drying method (convective or microwave) and pre-soaking (ionic surfactants and NaCl).

The synergistic effect of moderate heat and pressure on the physical properties and pectic substances of potato tissue

SummaryWhen a moderate heat (75–95 °C) and pressure (100 MPa) treatment (MHPT) was applied to potato, there were changes in texture, colour and tissue sloughing. Water‐soluble pectin release was determined and related to potato tissue firmness. Potato texture, after MHPTs at 75–85 °C, was firmer than that after heat treatments (HT). However, the firmness was almost the same in the MHPTs and HTs at 90 and 95 °C, and cooking at 100 °C for 20 min. The release of pectic substances was lower in MHPTs when compared with HTs at 75–85 °C and atmospheric pressure. There were almost no differences in colour between the treatments, and tissue sloughing was slightly higher in MHPTs. These results indicate that MHPT could be an effective alternative to conventional thermal or ultra‐high‐pressure processing. It provides higher food quality when texture, colour and tissue sloughing of potato are measured.

EFFECT OF MANNITOL TREATMENT ON ULTRASOUND EMISSION DURING TEXTURE PROFILE ANALYSIS OF POTATO AND APPLE TISSUE

ABSTRACT An ultrasound acoustic emission (AE) signal was recorded during texture profile analysis (TPA) of potato and apple tissue with different texture. The acoustic sensor was in contact with the sample through solid medium. Texture of the tissue was controlled by soaking it in different mannitol solutions. Both TPA and AE parameters change with the texture of potato and apple samples. However, correlation coefficients of linear regression of acoustic parameters are higher than TPA parameters and all of them are significant at a higher confidence level. Critical stress and strain indicate micro‐cracking of the material and they increase with decreasing tissue turgor. The ratio of the critical stress to hardness allows an analysis of sound duration. The sound lasts longer when the tissue is more turgid as a result of the decrease of critical stress to hardness ratio. Counts of AE recorded in the whole TPA test decreased logarithmically with tissue osmolality. The article showed that contact AE can be used for texture evaluation of potato and apple tissue.

RELATIONSHIP BETWEEN TEXTURE OF RAW AND COOKED POTATOES

ABSTRACT The relationship between texture of raw and cooked potatoes was studied. Tangent modulus of elasticity (E) using axial compression test and elasticity and viscosity parameters (E 1 , E 2 ,η1 andη2) from creep tests were used as measures of texture on cylindrical test specimens. Raw potatoes were stored at 5, 15, 25C and variable temperature for 16 or 26 weeks and subjected to textural evaluation periodically in the raw state or after cooking at 90C for 25 min. The values of E decreased by about 50.0–74.0% and 42.0–68.0% for raw and cooked potatoes, respectively. The elasticity and viscosity parameters decreased by about 30.0–55.0% and 25.0–70.0% for raw and cooked potatoes, respectively. The changes in the texture of raw potatoes followed a systematic trend with storage temperature. However, such a trend in relation to storage temperature was not observed for textural changes in cooked potatoes. There was an apparent correlation between the textural parameters of raw and cooked potatoes irrespective of storage conditions (P < 0.05). Such relationships led to the estimation of textural parameters of cooked potatoes directly from textural measurements of raw potatoes regardless of the storage history with R2ranging from 0.70 to 0.87.

Structural changes of potato tissue during French fries production

The purpose of the study was to determine some changes in the structure of potato tissue and the contents of non-starch polysaccharides and lignin in potatoes at particular stages of French fries production. The samples for laboratory studies were taken from potato tubers, strips and French fries collected from six locations of the technological line. Immediately after the samples were collected from the processing line, the texture of potatoes was determined using an Instron 5544. Structural changes in the tissue were determined using a Leo-435VP scanning electron microscope. Dry matter and non-starch polysaccharide contents were determined in the samples of processed potatoes. It was found that the texture of potato was changing during the technological process due to water losses and damages of potato tissue and consequent changes in non-starch polysaccharides and lignin. The greatest changes in potato tissue resulted from thermal processes: blanching, pre-drying and frying. Increases of non-starch polysaccharide and lignin contents were observed during these processes, owing to water losses in potato strips. The ultimate texture of French fries was developed during frying, by penetration of fat primarily into the external layer of strips.

Changes of polysaccharide content and texture of potato during French fries production

The purpose of the present study was to determine the changes in non-starch polysaccharide and lignin contents of potato during French fries production and also the relationship between the texture of the finished product and half-products, as a result of processing at each stage under investigation. The samples for laboratory studies were taken from potato tubers, strips and French fries collected from nine locations of a technological line. The greatest changes in non-starch polysaccharide content and texture of potatoes resulted from blanching and frying. The texture of French fries was mainly affected by pectin and cellulose. The texture of French fries can be predicted from the measurements of the texture of potato strips after blanching.