Peeling Loss Research Articles

Enzymatic Peeling of Potato: A Novel Processing Technology

Development of an innovative biotechnological method for potato peeling, closer to the ‘ideal’ peeling conditions of the product, was the main objective of the present research. Studies on enzymatic hydrolysis of potato peel were conducted. The efficacy of enzymatic peel hydrolysis was expressed in terms of reducing sugar content of the enzyme solution in which potato peel was incubated. Enzyme screening revealed that an enzyme solution containing a cellulase-xylanase mixture and amylase in a ratio of 1:1 showed good peel hydrolyzing efficiency of peeled peels. To further maximise the peel hydrolysis, condition parameters were optimised using response surface methodology (RSM). At the optimised conditions of 60 °C, pH 6 and 4 h, the reducing sugar yield in the solution was maximum. Characterization of the potato peel using microscopic techniques (scanning electron microscopy (SEM), atomic force microscopy (AFM)) further illustrated degradation of cell wall and reduction in the surface roughness of the peel after enzymatic treatment, which could enhance peel loosening from the intact potato. To further ascertain the efficiency of the process, studies were conducted with the selected enzyme on intact potato tubers under optimised conditions. Easy removal of peel was observed in enzyme-treated potato tubers, which showed 0.52% peel loss by abrasive peeling. The present process employing enzymes could be applied for peeling of intact potato as an alternative to conventional peeling process.

Performance evaluation of concentric screen grader

The machine main frame had dimensions 2000 mm × 1250 mm × 1000 mm, with a approximate cost of Rs. 45,000. The performance parameters such as actual capacity, grading efficiency of each grade, overall grading efficiency, damage loss and peel loss were studied in this work. The operating speed of the grader was maintained at constant speed 16 revolutions. The maximum grading efficiency of 96 and 62.3 per cent was found in onion and potato grading, respectively. The cost of the mechanical grading obtained was Rs. 30 per tonne. The ratio of cost for manual to mechanical grading worked out to be 12.45:1. During the performance test only peel loss was observed in onion grading while in case of potato grading more damage occurred. Therefore, this grading is only suitable for onion grading.

Standardizing fertility and crop geometry requirements of potato chipping variety Kufri Chipsona-4 for higher chip grade yield, quality and profitability

Field study was conducted at Central Potato Research Institute Campus, Modipuram to standardize the fertilizer and crop geometry requirements of newly released potato chipping variety Kufri Chipona-4 for higher chip grade tuber yield with good quality and higher profitability. Growth traits as well as chip grade tuber number did not influence due to different fertility levels and intra-row spacing treatments. Average tuber number/plant was higher under wider spacing. Highest chip grade, total and net tuber yield was recorded with highest fertility dose tested in the study (270 N + 80 P2O5 + 150 K2O kg/ha). Graded as well as net tuber yield was statistically similar under different crop geometry treatments. All the chipping quality parameters remained unaffected due to different fertility levels and crop geometry treatments except tuber dry matter content, which increased significantly in response to wider spacing and was maximum under 67.5 cm × 25 cm crop geometry (22.36%). Average chip grade tuber weight, which decides the peeling losses increased significantly in response to higher fertility levels and wider spacing. Maximum net returns (Rs. 95,937/ha) and B:C ratio (2.16) was recorded with fertilizer dose of 270 N + 80 P2O5 + 150 K2O kg/ha. Among crop geometry treatments the net returns was statistically similar, but the B:C ratio was statistically higher under 67.5 cm × 25 cm crop geometry (2.20). Therefore, chipping variety Kufri Chipsona-4 may be fertilized with 270 N + 80 P2O5 + 150 K2O kg/ha, along with 67.5 cm × 25 cm crop geometry (seed size 50 g) for achieving higher chipping grade tuber yield with good chipping quality and profits to the farmers.

Evaluation and Optimization of Steam and Lye Peeling Processes of Sweet Potato (Ipomea batatas) using Response Surface Methodology (RSM)

Abstract Sweet potato of uniform sizes and shape were subjected to steam peeling (temperature 80–100°C and peeling time 5–15 min) and lye peeling (sodium hydroxide concentration 8–12%, temperature 80–100°C and peeling time 3–5 min). Response surface methodology was used to analyze and optimize the process parameters in each case. For steam peeling, the peel loss and unpeeled surface area were 6.85 and 28.16%, respectively, while optimum peeling conditions where temperature and peeling time of 100°C and 5 min, respectively, for minimum peel loss and unpeeled surface area. For lye peeling, however, the peel loss and unpeeled surface area were 13.19 and 13.35%, respectively, and optimum peeling conditions were lye concentration, temperature and peeling time of 8.89%, 100°C and 4.75 min, respectively, for minimum peel loss and unpeeled surface area. The models developed in each case (R-squared of 0.9225 and 0.8428; 0.5929 and 0.8346) were adequate in producing responses as a function of the independent variables. From the optimized values and results obtained, lye peeling was more suitable for sweet potato.

Peeling of tomatoes using novel infrared radiation heating technology

Abstract The effectiveness of using infrared (IR) dry-peeling as an alternative process for peeling tomatoes without lye and water was studied. Compared to conventional lye peeling, IR dry-peeling using 30 s to 75 s heating time resulted in lower peeling loss (8.3%–13.2% vs. 12.9%–15.8%), thinner thickness of peeled-off skin (0.39–0.91 mm vs. 0.38–1.06 mm), and slightly firmer texture of peeled products (10.30–19.72 N vs. 9.42–13.73 N) while achieving a similar ease of peeling. IR heating increased the Young's Modulus of tomato peels and reduced the peel adhesiveness, indicating the tomato peels to loosen, become brittle, and crack more easily. Also, IR heating resulted in melting of cuticular membrane, collapse of several cellular layers, and severe degradation of cell wall structures, which in turn caused peel separation. These findings demonstrated the effectiveness of the novel IR dry-peeling process for tomatoes. Industrial relevance Development of a sustainable and non-chemical peeling technique for food processing industry is urgent. Currently, industrialized peeling methods such as hot lye or steam peeling are water- and energy-intensive operation and result in a large amount of waste effluent. Disposal of these wastewater containing high salinity and organic solids poses negative environmental footprints. Tomato processors have long been interested in pursuing a sustainable and non7 chemical peeling alternative in order to minimize waste effluent containing high salinity and organic loads and reduce the negative environmental impacts associated with conventional hot lye peeling. The emerging infrared dry-peeling technique offers a novel approach to eliminate the usage of chemicals and water in the peeling process while maintaining high quality peeled products. The study explored several crucial and fundamental aspects of developing infrared radiation heating technology as a sustainable tomato peeling method. The findings of this research provide scientific evidence of the benefits of infrared dry-peeling in comparison to the conventional hot lye peeling and have been used for the development of a pilot scale tomato infrared dry-peeling system.

Conventional and Alternative Methods for Tomato Peeling

Peeling is one of the most important unit operations in tomato processing. Most recently, three novel tomato peeling methods were reported: infrared, ohmic heating and power ultrasound. Steam/hot water and lye peeling have been the most commercialized methods, but compared to steam peeling, lye peeling is more preferred and has gained widespread application among processors due to its association with higher product yields and better product quality. However, with the ever-tightening environmental protection laws, concerns have arisen in the recent years regarding lye usage as well as its disposal, which calls for alternative chemical-free peeling methods that can effectively peel the tomato while minimizing peeling losses and improving product quality. This review highlights the conventional methods used in tomato peeling, their efficacy and the potential applications of infrared, ohmic heating and power ultrasonics as a novel technology for tomato peeling.

Analysis of the Factors Affecting the Value-Added to Dried Pineapple Fruits Using a Simple Interactive Computer Model

In this work, the effect of peel and reject losses on the value added to the dried pineapple fruits was analyzed. The major factors include final moisture content, Xwf; peel loss rate, Rp; reject loss rate, Rrj; and the reject-to-peel ratio, Rrj/Rp. The value added was expressed as the percent increase in value (PVA) which is an indication of price of dried fruits. Material losses were expressed as percent raw material lost (PRML), and total raw material lost per kg of raw material. The PVA decreases with increasing Xwf for all levels of initial moisture content. The PVA increases faster for Rp > 0.1 kg/kg from 67% to 90%. The PVA decreased with increasing Rrj/Rp. The PRML, on the other hand, increased faster with Rp for Rp > 0.1 kg/kg. However, PRML decreased faster as Rrj/Rp was increased. The total losses decreased with increasing Rrj/Rp and also with increasing Rrj.

`Assessment of Hybrid White Yam (Discorea Rotundata) Genotypes For The Preparation of Amala

Five hybrid white yam (D. rotundata) genotypes bred in Nigeria for high yield, cylindrical (rotund) tuber shape and resistance to diseases and pests were compared with an identified local best white yam landrace for their suitability in the preparation of amala (a darkish popular Nigerian ethnic food). The tubers of these experimental genotypes (TDr 89/02665, TDr 89/02677, TDr 95/19158, TDr 95/19177 and Nwopoko) were assessed for desirable processing characteristics before being processed into elubo. The elubo from these genotypes and that made from a national check (Ako – Isu cultivar) were reconstituted into amala for an organoleptic evaluation, with an ethnic Yoruba test panel. Results showed that the dry matter contents of the experimental fresh yam tubers ranged from 31.20% (TDr 95/19177) to 48.37% (TDr 89/02665) while the tuber peel loss (during processing) varied from 18.59% (TDr 95/19177) to 21.13% (TDr 95/19158). The amala prepared with elubo made from TDr 95/19158, TDr 95/1977 and Ako-Isu had black colour while the remaining amala samples had varying shades of grey colouration. Though all the elubo samples from the experimental yam genotypes were found to be usable in amala preparation, only the amala sample made from TDr 89/02677 compared favourably (especially in the handfeel sensory parameter) with that of the highly rated Ako-Isu cultivar.

Technical Note: Development of Infrared Radiation Heating Method for Sustainable Tomato Peeling

Although lye peeling is the widely industrialized method for producing high quality peeled fruit and vegetable products, the peeling method has resulted in negative impacts by significantly exerting both environmental and economic pressure on the tomato processing industry due to its associated salinity issues and wastewater disposal problems. The objective of this research was to develop alternative peeling methods with reduced or no caustic usage to produce high quality peeled tomatoes. The feasibility of using infrared radiation (IR) peeling and lye-IR peeling as alternative technologies was evaluated against control treatment which used regular lye peeling alone. Peeling performance and peeled tomato quality of three tomato cultivars were determined. The metrics for peeling performance were peelability, peeling easiness, and peeling weight loss. The color and texture of peeled tomatoes were measured as quality indicators. The study showed that IR peeling resulted in a similar peeling easiness but yielded lower peeling loss and firmer peeled product for the same or slightly longer peeling time when compared to regular lye peeling method. Pretreatment with low concentration of lye solution prior to IR treatment did not show any advantages over IR peeling alone. Because IR dry-peeling produced high quality product without using water and salts, it is concluded that it has a good potential as an alternative peeling method to the regular lye peeling method.

Mechanical peeling of pumpkins. Part 2: Modeling of peeling process

A novel mechanical peeling process using an abrasive-cutter brush which applies both abrasive and cutting forces was modeled. An energy consumption model of the peeling process is required to optimize the main influential factors as well as to limit peeling waste and consumed energy. The input and output variables which could be industrially applicable were used. Three variables, namely rotational velocity of the abrasive-cutter brush ( ω p), the degree of unevenness of produce surface ( φ), and the type of the abrasive-cutter brush ( λ), were chosen as independent variables and the “peeling losses” per unit time was selected as the output of the model. The developed model was verified using the experimental results of peeling by an abrasive-cutter brush for two varieties of pumpkin, as the case studies, named Jarrahdale and Jap. The results showed correlation coefficients between predicted and experimental values of the Jap (0.98) and Jarrahdale (0.96) were statistically significant.

Mechanical peeling of pumpkins. Part 1: Using an abrasive-cutter brush

Combining the functional basis of current peeling methods led to the development of a new innovative peeling method named the “abrasive-cutter brush”. It could utilize the benefits of the current peeling methods. The flexibility of brushes could provide easy access of the brush’s protrusions to different areas of the produce. Each protrusion on the brush, as a small cutting unit, cut and removed abrasively the peel pieces. The cutting action caused effective peeling while the abrasive action showed higher production rate compared with the existing methods. The optimized results revealed peeling effects of 18.60%/min and 20%/min for concave and convex areas, respectively at 0.18%/min peel losses. The optimum conditions of independent variables were 550 rpm for rotational velocity of brushes, 5 rpm for rotational velocity of vegetable holder, 20 mm lower than the middle horizontal plane of produce for the position of brushes, and medium for brush coarseness.

Sensory evaluation of amala from improved water yam (Dioscorea alata) genotypes in Nigeria

Production of improved water yam (Dioscorea alata) genotypes that are suitable for the preparation of amala (a popular darkish Nigerian food) would likely enhance the economic importance of the crop in Nigeria. Fermented flour (oven dried and sun dried) made from tubers of eight improved D. alata genotypes (TDa 00/00364, TDa 00/00194, TDa 00/00103, TDa 00/00104, TDa 99/00240, TDa 99/01176, TDa 98/01166, Um 680) and two landraces (TDa 92-2, Ominelu) were reconstituted into amala, and organoleptically evaluated. Relevant characteristics of the experimental yam tubers, and their intermediate products (chips and flour), were also evaluated for desirable qualities. Results showed that the tubers shape could affect the percentage peel loss of the tubers during processing. The dry matter content of the experimental fresh tubers varied from 20.05 to 45.63%, while the moisture content of the oven dried fermented (pH 5 - 6) yam flour (elubo) samples (used for the amala preparation) ranged from 8.30 to 9.80%. The colour observed in the amala samples varied from light brown to black. Though most of the experimental genotypes could be used in preparing amala, only TDa 00/00194 and TDa 00/0364 were highly rated (in relevant sensory parameters) for the preparation of the foodstuff (which is traditionally made from processed tubers of some Diosocrea rotundata cultivars).

Physical properties of pistachio nut and its kernel as a function of moisture content and variety. Part II. Gravimetrical properties

Several gravimetrical properties of five varieties of pistachio and its kernel (Akbari, Badami, Kalle-Ghuchi, Momtaz and O’hadi, which are major commercial Iranian pistachio varieties) were investigated and compared in terms of unit mass, shell ratio, peeling loss, true volume, true density, bulk density, porosity, at five moisture contents levels in the range from initial moisture content at harvesting to completely industrial dried condition. Peeling loss percentage of all varieties was between 38.26% and 43.39%, whereas shell ratio percent obtained between 43.54% and 47.10%. The unit mass of Akbari, Badami, Kalle-Ghuchi, Momtaz and O’hadi pistachio nuts were 1.334–1.696, 1.014–1.250, 1.599–2.234, 1.081–1.403, 1.105–1.680 g, respectively. However, the range of unit mass for Akbari, Badami, Kalle-Ghuchi, Momtaz and O’hadi pistachio kernels were 0.723–0.873, 0.553–0.743, 0.832–1.277, 0.524–0.759, 0.547–0.873 g, respectively. The true volume of Akbari, Badami, Kalle-Ghuchi, Momtaz and O’hadi pistachio nuts obtained between 1.602 and 2.206, 1.175 and 1.422, 1.857 and 2.589, 1.256 and 1.628, 1.291 and 1.873 cm 3. However, the range of true volume for Akbari, Badami, Kalle-Ghuchi, Momtaz and O’hadi pistachio kernels were 0.838–1.116, 0.642–0.854, 0.965–1.474, 0.609–0.874, 0.634–1.013 cm 3, respectively. The effect of moisture content on unit mass, volume, true density, and bulk density of pistachio nuts and their kernels showed a linear increase with increasing moisture content. However, the porosity decreased linearly with the increasing moisture content in pistachio nuts and their kernels.

Abrasive peeling of pumpkin

This paper presents new abrasive peeling methods for the pumpkin. The design of two innovative peeling devices, called abrasive pads and abrasive disks, are aimed at evenly peeling the varieties of pumpkin with uneven surfaces (i.e. Jarrahdale and Jap). The performance of the peeling process was evaluated for each method by using the Taguchi method and compared. High and equal peeling effect in convex and concave areas, and low peel losses, were the criteria of experiments. Optimization of the results of abrasive pads indicated the possibility of the peeling effect in concave and convex areas as 4.5 and 3.83 %/min respectively with peel losses of 0.14 %/min. These results were obtained in optimum conditions of independent variables involving 0° flap angle, overlap of 26.5 mm, 140 rpm of peeler head speed, and 10 rpm of vegetable speed. Higher peeling productivity compared to abrasive pads was achieved by using abrasive disks. Optimized results showed the peeling effect can approach 71.85 and 79.01 %/min in concave and convex areas, respectively with 1.02 %/min peel losses. The results were obtained in optimum conditions of independent variables of abrasive disks including abrasion grade of 24, vegetable speed of 5 rpm, peeler head speed of 1000 rpm, pushing force of 1.65 N, and with the specially shaped foams (shape A).

銅箔とプリント樹脂基板の密着性におけるエージング処理の影響

It would be expected that the corrosion phenomenon may also be altered among the planes, since the zinc is deposited in preferred orientation. In the present study, we investigated the effect on adhesion between the orientation of zinc plating on copper foils and peel loss after HCl immersion, after the electro-galvanized copper foils were exposed to the aging atmosphere (313 K, 90%RH, 7 days). The experimental results indicated that the foils plating (0002) oriented zinc basal plane had a lower peel loss after HCl immersion than the other orientations.The XPS (X-ray Photoelectron Spectroscopy) and rf-GDOES (rf-Glow Discharge Optical Emission Spectroscopy) studies were performed to support the mechanism of the peel loss after HCl immersion. It was found that it was difficult to oxidate the zinc layer of the (0002) oriented specimen, rather than the other orientations, after the aging test. It is considered that the oxidation of zinc results in a change of the layer structure on the surface of the foils, and hence the peel loss took place after HCl immersion.

Manufacturing of par-fried French-fries: Part 2: Modelling yield efficiency of peeling

The paper outlines the yield efficiency of steam peeling. It was proven that peeling potatoes manually with sandpaper results in the lowest possible peel losses. These losses were desired or wanted losses. However, in practice steam peeling results not only in wanted losses but also in substantial unwanted losses of about 7.9%. A model was developed to predict peel losses and heat ring (HR) development during steam peeling. Based on this model it was shown that creating a homogeneous peel removal effect with minimum HR development should be the main approach to decrease unwanted losses during steam peeling in the future.

Manufacturing of par-fried French-fries: Part 1: Production yield as a function of number of tubers per kilogram

Mass losses during peeling and size sorting of cut strips in French-fries production are heavily influenced by potato size and shape. In this study the number of tubers per kilogram ( N) is used as a raw material parameter to estimate the average principal dimensions, volume, surface area and specific surface area of potato tubers. A method called ‘numerical shell’ was developed to estimate the surface area of ellipsoid bodies. This method can be used for other three-dimensional objects as well when the analytical surface area equation is not applicable. The study is focused on Solanum tuberosum L. cv.: Agria, Asterix and Bintje. The paper outlines also the relationship between production yield and number of tubers per kilogram. It was shown that the peel losses and specific surface area increase proportional by N 1/3. Mass losses due to sliver removal increase linearly proportional with N.

Abrasive peeling of potatoes

For the processing of potatoes in any form, removal of peel is an important unit operation. Hence, a power operated batch type potato peeler was developed and its performance was evaluated. The main parts of the machine are a peeling drum and a water spraying unit. The peeling drum with protrusions on the inside surface rotates and detaches peel from potatoes by abrasion. The water spraying unit washes the potatoes and simultaneously peel is removed from the drum through the perforation along with the flow of water. The capacity of the machine is 100 kg/h with a peeling efficiency and peel losses of 78% and 6%, respectively. The machine costs around Rs 6500.00 ($250) along with an electric motor and is suitable for a small scale processor of potato chips and other products. The estimated cost of peeling of 1 ton potatoes is only Rs 100.00 ($3.85).

Crisp quality of two potato varieties: Effects of dehydration and rehydration

AbstractCrisps adversely made from stored whole potatoes turn brown, whereas texture is adversely affected when crisps are made from dehydrated slices. Rehydration as a step prior to crisp‐making has been investigated in two commercially grown potato varieties in Mauritius. The raw material was analysed for physical, chemical and processing characteristics including peeling losses, blanching time, drying rates and yield. Rehydration rates and ratios were determined. The sensory characteristics of the crisps were evaluated. Potatoes of the Exodus variety were smaller with more eyes and had higher peeling loss than those of the Spunta variety. The former had higher specific gravity and better drying characteristics. There were no significant differences between the varieties in respect of blanching time, chemical composition and crisp quality, and the drying curves were similar. Slight differences were observed in the rehydration characteristics. Crisps made from dehydrated slices were inferior in texture and taste to those of the control. However, crisps made from rehydrated slices were comparable to control crisps.

Peeling Sugarbeets by Use of High Pressure Steam

ABSTRACf A high pressure steam peeling technique was used successfully to peel uncrowned and crowned sugar­ beets. Treatments of 40-60 seconds with 1825 kPa (250 psig) steam followed by mechanical brushing with a stiff nylon brush produced uncrowned peeled beets with only minor amounts of skin or peel still intact. For these treatments, peeling weight losses of 3.5­ 5.8% were obtained resulting in losses of 1.8-2.8% of the sugar in the original beets to the peel fraction. Crowned beets could be peeled after a shorter steam treatment time (20-30 sec). For crowned beets, peel and sugar losses were 2.9-3.9% and 1.3-1.7%, respec­ tively. The peeled beets were lower than the peel fraction by factors of 3 or more in ash, nitrogen, sodium, potassium, calcium, and magnesium con­ tent. Brei juice and thin juice purities from peeled uncrowned and peeled crowned beets were up to 1.6% (relative) higher than extracts from the unpeeled control beets. Color values of thin juice from the peeled beets were not significantly different than those obtained from the control beets. All peel frae­ tions were low in sugar (28-41 %, dry basis) and pro­ duced thin juice with low purities (53.2-75.5%) and high color values (2000-7500 ICUMSA).