Steam Peeling Research Articles

АВТОМАТИЗИРОВАННАЯ СИСТЕМА СУШКИ И ОЧИСТКИ РАСТИТЕЛЬНОГО СЫРЬЯ С ПРИМЕНЕНИЕМ ТЕПЛОВЫХ АККУМУЛЯТОРОВ И ЭЛЕКТРОНАГРЕВАТЕЛЕЙ С ЭФФЕКТОМ САМОРЕГУЛИРОВАНИЯ ТЕМПЕРАТУРЫ

The paper presents an automated system for processing fruit and vegetable products, which includes such technological operations as steam peeling (thermovacuum method), cutting, convective and vacuum drying of fruit and vegetable products. For efficient operation of the plant a control system is used, which provides full automation of the whole complex of technological elements. The plant has a high level of energy efficiency, as it uses thermal accumulators (with the effect of thermomagnetic convection) and heaters with temperature self-regulation. The parameters of the operation modes of thermal accumulators agree with the operation of the heater with adaptive energy consumption (with variable power and constant temperature) depending on the temperature of heating of plant raw materials. At the first stage, when intensive heat flow is required for drying - thermal accumulators provide inertia-free heating of horticultural products. The function of the heater is connected with controlled heating depending on the temperature of plant raw material, providing heat flow correlated with the operation of thermal accumulators. The use of combined and adaptive heating from thermal accumulators and electric heaters allows for uniform temperature distribution (temperature field), which ensures efficient processing of vegetable raw materials. Automated change of heating power from electric heaters and thermal accumulators provides the possibility of adaptation to any power electric network based on the need for the level of processed horticultural products, and the use of thermal accumulators allows to accumulate thermal energy from solar collectors.

Experimental investigation of chestnut shells gasification

Fossil fuels substitution with renewable energy sources is necessary for an effective decarbonization. Biomass can represent a valid alternative to fossil fuels, reducing greenhouse gas emissions. Furthermore, bioenergy generation avoids costs and problems related to biomass disposal. This study presents the energetic valorisation of chestnut shells, a byproduct of the chestnut transformation processes. Through a thermo-conversion system based on gasification, this material was considered not as a waste, but as a resource to be exploited to produce bioenergy and biochar. The fuel gas produced through the gasification process can partially replace the LPG currently used to meet the energy required for the brulage and steam peeling processes. Experimental gasification tests were carried out to evaluate this biomass by means of a laboratory scale micro-gasifier (Imbert downdraft type). Chestnut shells were pelletized with a pelletizer machine to avoid the bridging effect inside the gasifier and increase its energy density. The fuel gas obtained was sampled and analyzed to measure its composition and HHV. In addition, the gasification efficiency was calculated obtaining a value of 70%, a result in line with the ones obtained with higher quality biomasses.

Advances in peeling techniques for fresh produce

AbstractPeeling is a significant stage of post‐harvest processing of fruits or vegetables. The most adopted peeling methods are mechanical, steam, chemical, and manual peeling. Apart from these methods, some other methods such as enzymatic, infrared, and some methods like ohmic heating, ultrasound‐assisted lye peeling, and pulse electric field‐assisted steam peeling are also used. To concern the freshness of the product, manual peeling is the most ideal method but it consumes an inefficient amount of time and physical labor. Mechanical method consumes less time and under this process, the collected peel can be utilized in the by‐product stream. Lye peeling is an efficient method but the disposal of lye after the process is an environmental concern. Adjusting this system to include ultrasound, ohmic heating and CO2 laser drilling coupled with moderate electric fields can be used to reduce the lye requirement. Enzymatic peeling produces good quality products with low waste but can only be applied to fruits whose distinct separation of peel from the flesh is needed. PEF‐assisted steam peeling helps immensely in terms of cost‐saving by reducing the high use of steam. Infrared dry‐peeling only heats the superficial layer of fruits and possesses minimal effect in an edible inner portion of fruit. It uses less time with low peeling loss, high peelability, high peeling yields, thin skin is peeled‐off, but needs more research to justify industry implementation. In conclusion, the novel method assisted peeling can be used to save the time, environment, and quality of the fruit or vegetables.Practical applicationsPeeling is the primary post‐harvest process applies to the group of foods and it is crucial to have minimal damage to the products at this stage. For utilization of the peeling process in any processing, the knowledge of the all available and efficient peeling process for the individual fruit or vegetable is necessary. The main objective of the review is to outline the applicable current and novel peeling techniques for the commodities with their process conditions, mechanisms, advantages, and disadvantages.

Implementation of PEF Treatment at Real-Scale Tomatoes Processing Considering LCA Methodology as an Innovation Strategy in the Agri-Food Sector

In Europe, science and innovation are boosting the agri-food sector and, in parallel, are helping to decrease greenhouse gas emissions (GHG) and European dependency on non-renewable resources. Currently, it is well-known that this sector contributes to the consumption of energy and material resources, causing significant environmental impacts that require a complex and comprehensive environmental evaluation in order to manage them effectively. This becomes even more complicated when new technologies are reaching the level of technological maturity needed to be installed in the production lines. To address this scientific challenge, the life cycle assessment (LCA) has been used in this paper to evaluate the potential of pulsed electric fields (PEF) technology at an industrial scale to facilitate the steam peeling of tomato fruits. Considering the thermo-physical peeling stage, the LCA has shown that PEF technology is environmentally friendly, because when PEF technology is applied, all the considered environmental indicators improve between 17% and 20%.

Demonstration Tests of Infrared Peeling System with Electrical Emitters for Tomatoes

. Infrared (IR) dry-peeling is an emerging technology that could avoid the drawbacks of steam and lye peeling of tomatoes. The objectives of this research were to evaluate the performance of an IR peeling system at two tomato processing plants in California and to compare product quality, peelability, and energy consumption of IR and steam peeling. The system was continuously operated using tomatoes of different sizes and cultivars. High percentages (62% to 85%) of fully peeled tomatoes were obtained and varied depending on tomato cultivar and seasonality. IR dry-peeled tomatoes had a firmer texture than steam and lye peeled tomatoes. IR peeling achieved a peeling loss in the range of 17% to 42%, which was lower than typical loss in the industry. Small tomatoes had higher loss than large tomatoes in the late season. Thermal energy consumption of the proposed technology in full-scale production (10 ton h-1) is predicted to be 117.0 and 137.3 MJ ton-1 for indoor and outdoor operation, respectively. The estimated energy savings of IR dry-peeling should be 22% and 28% compared to lye and steam peeling, respectively. The demonstration results showed that the IR dry-peeling technology could be a viable alternative to lye and steam peeling.

Effect of ohmic heating on tomato peeling

Current industrial methods of tomato peeling are lye and steam peeling, both of which suffer from various disadvantages; caustic, high pH waste with the former, and excessive water use with the latter. In this study, ohmic peeling was attempted to potentially address these problems. Tomatoes were ohmically heated in NaCl solution under various conditions of field strength, initial temperature and number of tomatoes, resulting in peeling with greatly reduced lye concentrations. Field strength, NaCl concentration, initial temperature and fruit concentration all significantly influenced peel cracking time. Results indicated that in terms of quality of peeling, the best conditions of ohmic peeling were: 0.01 g/100 ml NaCl with 8060 and 9680 V/m, and 0.03 g/100 ml NaCl with 6450 and 8060 V/m. These conditions showed potential for processing because they required a reasonably short time (approximately 1 min). Further, the potential to preheat the media to 40 °C or more with reusable media could further shorten the peeling time.

Pectin characterisation in vegetable waste streams: A starting point for waste valorisation in the food industry

Vegetable waste streams, which are a major disposal issue in food industry, present a promising source of compounds which may be valorised because of their favourable functional features. In this context, the potential of five vegetable waste streams (rejected carrots, carrot steam peels, green beans cutting waste, leek cutting waste and celeriac steam peels) as a source for the extraction of pectin with interesting structural, and hence functional, properties was evaluated. Specifically, cell-wall components were extracted from the waste streams as alcohol-insoluble residue and subsequently fractionated into different (pectin) fractions based on their solubility. The pectic polysaccharides were characterised in terms of GalA content, neutral sugar content, linearity/branching, degree of methyl-esterification (DM), molar-mass distribution and the presence of bound protein. Pectin characterisation revealed considerable differences between the pectic polymers present in the investigated waste streams. For example, pectin in carrot steam peels showed a low DM, whereas the cutting waste of leek contained pectin with a very high DM. Furthermore, the level of protein bound to pectin was generally highest in carrot-derived waste streams. Depending on the intended pectin functionality, a deliberate choice for one of these vegetable waste streams as a source for pectin extraction can be made.

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.

Integration of Biohydrogen Production with Heat and Power Generation from Biomass Residues

The employment of renewable sources rather than fossil fuels in the production of hydrogen is an important step to achieve a sustainable hydrogen economy in the future. Besides biomass gasification, production of hydrogen from renewable sources is also possible in a fermentative way through thermophilic (dark) fermentation and/or photo-heterotrophic fermentation. Depending on pretreatment procedure, considerable heat demand is necessary to produce hydrogen from agricultural residues and food processing. While heat demand in the pretreatment step can be reduced by heat integration measures, significant heat input is still necessary in the dark fermentation step. The paper evaluates possible contributions of utilizing process residues to cover the heat demand of the biohydrogen production. Process options for three types of feedstock for biohydrogen production have been investigated towards the potential of heat self-supply of the process. Results show that the heat demand of biohydrogen production from barley straw and potato steam peels can be covered from heat of biogas utilization obtained from process residues. For feedstock thick juice still a heat deficit of 0.29 MW is observed.

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.

Biohydrogen production from untreated and hydrolyzed potato steam peels by the extreme thermophiles Caldicellulosiruptor saccharolyticus and Thermotoga neapolitana

Production of hydrogen by the extreme thermophiles Caldicellulosiruptor saccharolyticus and Thermotoga neapolitana was studied in serum flasks and in pH-controlled bioreactors with glucose, and hydrolyzed and untreated potato steam peels (PSP) as carbon sources. Two types of PSP hydrolysates were used: one in which the starch in the PSP was liquefied with alpha-amylase, and one in which the liquefied starch was further hydrolyzed to glucose by amyloglucosidase. When the PSP hydrolysates or untreated PSP were added at circa 10–14 g/L of glucose units, both strains grew well and produced hydrogen with reasonable to high molar yields (2.4–3.8 moles H 2/mole glucose units), and no significant production of lactate. The hydrogen production rates and yields were similar with untreated PSP, hydrolyzed PSP, and pure glucose, showing that C. saccharolyticus and T. neapolitana are well equipped for the utilization of starch. When the concentrations of the substrates were increased, growth and hydrogen production of both strains were hampered. At substrate concentrations of circa 30–40 g/L of glucose units, the molar hydrogen yield of C. saccharolyticus was severely reduced due to the formation of high amounts of lactate, while T. neapolitana was unable to grow at all. The results showed that PSP and PSP hydrolysates are very suitable substrates for efficient fermentative hydrogen production at moderate substrate loadings.

Life cycle inventory analysis of biological hydrogen production by thermophilic and photo fermentation of potato steam peels (PSP)

The environmental impact of hydrogen production in a 2-step fermentation process from potato steam peels was identified. Based on the ISO 14040, ISO 14044, ecoinvent data base and SimaPro 7.1 software, a life cycle inventory analysis was performed. Reflecting the current state of process development, the LCA shows an impact of 4.3 points (pts) which is at least 5.7 times higher than the selected reference technologies regarded as state-of-the-art. Over half (53.5%) of the environmental impact is generated by the use of phosphate in the fermentation processes. A sensitivity analysis shows a potential impact reduction of 65.8% due to recirculation of sewage or reduction of buffer concentration. The analysis also demonstrates that the production of the process ingredients cause 98.3% of the environmental impact. The impact of the process itself is 0.07 pts which is up to 10 times lower than the reference technologies.

Potential use of thermophilic dark fermentation effluents in photofermentative hydrogen production by Rhodobacter capsulatus

Biological hydrogen production by a sequential operation of dark and photofermentation is a promising route to produce hydrogen. The possibility of using renewable resources, like biomass and agro-industrial wastes, provides a dual effect of sustainability in biohydrogen production and simultaneous waste removal. In this study, photofermentative hydrogen production on effluents of thermophilic dark fermentations on glucose, potato steam peels (PSP) hydrolysate and molasses was investigated in indoor, batch operated bioreactors. An extreme thermophile Caldicellulosiruptor saccharolyticus was used in the dark fermentation step, and Rhodobacter capsulatus (DSM1710) was used in the photofermentation step. Addition of buffer, Fe and Mo to dark fermentor effluents (DFEs) improved the overall efficiency of hydrogen production. The initial acetate concentration in the DFE needed to be adjusted to 30–40 mM by dilution to increase the yield of hydrogen in batch light-supported fermentations. The thermophilic DFEs are suitable for photofermentative hydrogen production, provided that they are supplemented with buffer and nutrients. The overall hydrogen yield of the two-step fermentations was higher than the yield of single step dark fermentations.

Techno‐economic evaluation of a two‐step biological process for hydrogen production

An integrated biological process for the production of hydrogen based on thermophilic and photo-heterotrophic fermentation was evaluated from a technical and economic standpoint. Besides the two fermentation steps the process also includes pretreatment of the raw material (potato steam peels) and purification of hydrogen using amine absorption. The study aimed neither at determining the absolute cost of biohydrogen nor at an economic optimization of the production process, but rather at studying the effects of different parameters on the production costs of biohydrogen as a guideline for future improvements. The effect of the key parameters, hydrogen productivity and yield and substrate concentration in the two fermentations on the cost of the hydrogen produced was studied. The selection of the process conditions was based mainly on laboratory data. The process was simulated by use of the software Aspen Plus and the capital costs were estimated using the program Aspen Icarus Process Evaluator. The study shows that the photo-fermentation is the main contributor to the hydrogen production cost mainly because of the cost of plastic tubing, for the photo-fermentors, which represents 40.5% of the hydrogen production cost. The costs of the capital investment and chemicals were also notable contributors to the hydrogen production cost. Major economic improvements could be achieved by increasing the productivity of the two fermentation steps on a medium-term to long-term scale.

A SIMPLE CHESTNUT PEELING PROCESS AND PROPERTIES OF THE PEELED KERNELS

We developed a simple, fan-driven process to peel chestnuts that utilizes impact to remove shells and pellicle. A working prototype has peeled over 10 tons of Chinese chestnuts at a maximum peeling rate of 150 kg/h output. Capital costs and operating costs of the process are a fraction of the cost of steam or flame peeling technologies. The device peels partially dried, fresh chestnuts or completely dried chestnuts, removing both the shell and pellicle. The peeled chestnut kernels emerge in a fresh, uncooked condition. Fresh peeled kernels are perishable, but have a minimum 3-week shelf life under refrigeration. Alternatively, dried kernels and chestnut flour are shelf-stable products that can be derived from this process. Optimum peeling performance depends on proper temperature and moisture preconditioning. Color, texture, flavor, and shelf-life of peeled kernels depend on internal moisture content and storage temperature and humidity. Protocols for best peeling performance and subsequent marketing are based on 15 years' experience with this process. Kernel moisture content, sugar content, and microbiological risks are all interrelated factors that need to be controlled for successful commercial use of this process.

Composition of Phenolic Compounds and Glycoalkaloids α-Solanine and α-Chaconine during Commercial Potato Processing

The influence of a commercial production process for dehydrated potato flakes on the content of free phenolic compounds, total phenolics, and glycoalkaloids in potatoes during the subsequent processing steps was determined. Processing byproducts, such as potato peel (steam peeling), mashed potato residues, and side streams (blanching and cooking waters), have also been investigated. A high-performance liquid chromatography (HPLC) method was developed to separate and quantify caffeic acid, gallic acid, ferulic acid, p-coumaric acid, p-hydoxybenzoic acid, protocatechuic acid, vanillic acid, catechin, and three isomers of caffeoylquinic acid: chlorogenic, neochlorogenic and cryptochlorogenic acid. Determination of the glycoalkaloids alpha-solanine and alpha-chaconine was performed by using a high-performance thin-layer chromatography (HPTLC) method. The deliverables reveal that processing potatoes to potato flakes remarkably diminishes the content of the analyzed compounds, mainly due to peeling and leaching. The influence of thermal exposure is less significant. About 43% of the initial phenolic acids and 10% of the glycoalkaloids remain after processing. The results of the total phenolic content assay by Folin-Ciocalteu reagent are proportional to the content of phenolic compounds determined by HPLC. Steam peeling has a higher influence on glycoalkaloid losses compared to that on phenolics. The highest amounts of phenolic compounds and glycoalkaloids were found in peeling byproduct. During processing, the amount of chlorogenic acid decreased, whereas the concentration of neochlorogenic acid increased due to isomerization. The impact of the results on potato processing technology is discussed.

Assessment of tomato pericarp mechanical damage using multivariate analysis of magnetic resonance images

During steam peeling, severely bruised tomatoes will disintegrate, leading to loss of product. The overall purpose of this study was to develop an in-line method to detect damaged pericarp tissue in processing tomatoes. Magnetic resonance (MR) imaging methods characterize the environment of water protons in plant tissue, resulting in contrast between image pixels corresponding to bruised and sound tissue. Many types of MR imaging protocols are available; in this study, the multivariate image analysis (MIA) method of partial least squares (PLS) was used to determine the optimal MR pulse sequences for tomato pericarp damage assessment. A set of 13 congruent MR images of each of 112 processing tomatoes was used for prediction. The images were created by varying key parameters in 4 different MR pulse sequences. These multivariate images were used to predict the pixel intensities in regions of interest (ROIs) corresponding to the pericarp of the tomato. The pixels in the ROIs for each tomato sample were assigned a value between 0 (no damage) and 1 (extensive damage), corresponding to the conductivity score for that sample, measured after imaging. PLS models of 1–13 latent variables were generated, and cross validation was performed. The root mean square error of cross validation (RMSECV) of the PLS models leveled off after 8 latent variables, so this model was used for conductivity score prediction. The 8 latent variable model captured 97% of the variance in the independent variable (the MR images) and 54% of the variance in the dependent variable (the conductivity scores). The Variable Importance in Projection scores for the 13 MR image sequence types in the chosen model indicated that the Fast Spin Echo sequence with receiver gain of 10 and Turbo Fast Low-Angle Shot sequences with inversion times of 400 ms, 800 ms, 1000 ms, and 1200 ms had the strongest influence on the model. The root mean square error of calibration (RMSEC) and RMSECV of a final model including only these five sequences were low: 0.16 and 0.17, respectively. Thus, MIA of MR images of tomato proved to be effective for predicting the conductivity score of pericarp tissue in tomatoes.

Life cycle assessment of hydrogen produced from potato steam peels

Hydrogen from renewable energy is considered a promising alternative to traditional petroleum-based transportation fuels. Potato steam peels can be used as feedstock to produce hydrogen through fermentation processes. Life cycle assessment is used as an analytical tool to evaluate the main environmental benefits and burdens of using potato steam peals to produce hydrogen rather than to feed animals. Inventory data are derived from the literature and ecoinvent. Impacts are evaluated using IMPACT 2002+. The results show that producing hydrogen from potato steam peels offers clear advantages over a direct use of peels to feed animals. A factor of two to three is observed in the reduction of greenhouse gas emissions, in the savings of non-renewable resources and in the reduction of human health impacts. The two-stage bioreactor is observed to consume around 25MJ and to emit between 1000 and 1500g of CO2 per kilogram of hydrogen produced.

Effects of thermal processing and fruit matrix on β-carotene stability and enzyme inactivation during transformation of mangoes into purée and nectar

Effects of thermal mango processing on β-carotene stability and inactivation of peroxidase (POD) and polyphenol oxidase (PPO) were systematically evaluated on a laboratory scale, mimicking typical operations in continuous and small-size batch production of mango purée. Treatments comprised pasteurisation between 85 and 93 °C up to 16 min of holding time, with pasteurisation values ( P T ref = 93.3 ° C z = 8.9 ° C ) of 0.34–14.91 min, and thermal routines usually applied in enzymatic maceration for pectin degradation to standardise mango pulp viscosity. Although significant trans– cis-isomerisation of β-carotene ( P < 0.05) was shown by the formation of 13- cis-β-carotene, maximum vitamin A loss during pasteurisation of mango purée did not exceed 15.4%, owing to a total β-carotene retention of 93%. PPO was readily inactivated after 1 min, whereas residual POD activities of 4.0–6.3% were detected, even after 16 min, at all pasteurisation temperatures. To study the influence of the fruit matrix during pasteurisation, β-carotene stability was additionally evaluated at modified physical states in aqueous and in oil-in-water (o/w) emulsified model preparations. After disintegration of the mango matrix, trans– cis-isomerisation was higher than in model preparations, indicating a non-crystalline state of β-carotene in the mango mesocarp. In semi-continuous production of mango nectar on a pilot-plant scale, evaluated by stepwise process control, four heating treatments used for steam peeling, thermal inactivation of endogenous enzymes prior to enzymatic pulp liquefaction, and pasteurisation of purée and nectar, respectively, consistently resulted in a final retention of 83% of the vitamin A value of the fruit dry matter.