Hot Lye Research Articles

Study of the processing of dehydrated black olives from oxidized black olives

Changes in the processing of black olives, together with the dehydration of the latter, were investigated in order to develop a new product with similar physicochemical and sensory characteristics to commercial dry-salted olives. Large fruit of the Hojiblanca cultivar (160 fruit/kg), preserved in brine for eight months, were used. It was found that these olives must be elaborated with hot lye (40 °C) to reduce their strong firmness. Moreover, several changes must be introduced during the color fixation stage including the addition of a concentration of NaCl higher than 6 g/100 mL, acidification with lactic acid and a low concentration of ferrous gluconate (<0.5 g/L). In addition, the kinetic constant and activation energy during the dehydration of the olives by infrared heating were obtained. Finally, it must be noted that this new product was assessed without any negative sensation by tasters one year after packing.

Microwave-assisted infrared dry-peeling of beetroot: Peeling performance, product quality, and cell integrity

The use of low power-short time microwave (MW) treatment before infrared (IR) heating could help improve the peeling performance of beetroot. MW-assisted IR peeling (MWIR) and IR peeling of beetroot were investigated and compared with the conventional hot-lye peeling method. Also, the effects of these peeling methods on the quality and microstructure were evaluated. Hot-lye peeling at 95 °C for 40 s and 60 s was used as control. Results showed that MW-assisted IR peeling at power 640 W and heating time 7 min produced samples with the highest peelability (99.4%), lowest peel thickness (0.075 mm), and peel remaining (0.8%), lower peeling loss (4.23 g), and better peeling easiness when compared with lye peeling and IR peeling. IR peeling alone produced samples with the lowest peeling loss (2.87 g) and surface colour change, and the highest vitamin C retention (75.32%) than MW-assisted IR and lye peeling respectively. The product microstructure for the different peeling methods showed cellular distortion as a result of thermal expansion. MW pretreatment shows a promising potential to further develop the IR dry-peeling method, to replace the conventional hot lye chemical peeling.

Disposal of slime storage lyes during potash production

Processing of potash production slime storage lyes with the aim to obtain useful components with evaporation method was investigated. It was estimated that during the first and the second stages of evaporation in vacuum crystallization devise (VCD) sodium chloride was crystallized from the hot (90-95 °C) lye, and potassium chloride - when cooling down to 35 °C. Content of basic components (KCl &amp; NaCl) in the precipitate was more than 90 %. During the third stage, while cooling down to 20-25 °C, and the fourth stage from the hot (90-95 °C) lye, a mixture of sodium and potassium chlorides was crystallized. During the next evaporation and cooling up to 20-25 °C together with sodium and potassium chlorides, carnallite was obtained, the decomposition of which leads to potassium chloride formation.

A semiconductor-insulator heterojunction induced by hydroxyl groups formed on the surface of SiO2 microspheres

Photocatalyst@carrier composites have great potential for the treatment of environment-related issues due to their enhanced photocatalytic activity and increased recovery rate. The surface properties of the carrier could affect the stability and the activity of the nanoparticles and could play a crucial role in the applicability of these nanoparticles. The SiO2 microspheres (MS-SiO2) were treated with hot lye to support the UV-activated TiO2 photocatalyst and visible light-activated CdS photocatalyst. The influence of the surface characteristics of microspheres on the performance and structural peculiarities of the photocatalyst nanoparticles was investigated, with the interactions on the interface between the semiconductor and the carrier. It was found that the activity and the hydroxylation of the surface of MS-SiO2 were enhanced after alkali treatment, which increased the anchoring sites and the dispersion of the nanoparticles. Moreover, the charge separation and the interface interaction between the semiconductor and the carrier were enhanced, inducing the directional transfer of photogenic carriers. Furthermore, a semiconductor-insulator heterojunction was built between the semiconductor and the carrier, resulting in a change in the band structure of the photocatalyst. This work may provide new considerations for the design of photocatalyst/carrier composites.

Peeling of kiwifruit using infrared heating technology: A feasibility and optimization study

Infrared (IR) technology has been studied as an alternative to conventional food processing technologies. The IR technology has attractive merits such as uniform heating, high heat transfer rate, reduced water, and energy consumption and improved product quality and safety. This research studied the feasibility of kiwifruit peeling using IR heating. The response surface methodology (RSM) was used to investigate the effects of IR radiation power (250–850 W), the distance between IR emitter and sample (10–70 mm) and heating time (45–125 s) on the peeling performance and physicochemical properties of kiwifruit. Lye-peeling was used as the control treatment to compare the efficiency of IR peeling. Heating with a power of 446 W at the distance of 70 mm for 125 s was found to be the optimum operating conditions for the IR peeling of kiwifruit. Under these conditions, the results were a peelability of 90%, weight loss of 4.5%, peel thickness of 0.4 mm, surface temperature of 64.1 °C, puncture force of 57.7 N, color difference of 2.4 and ascorbic acid content of 140 mg/100 g fresh fruit. Compared to hot lye peeling, the IR radiation heating caused significant reduction in weight loss, surface temperature, and color differences. It also maintained the firmness of fruits.

A novel two-step ultrasound post-assisted lye peeling regime for tomatoes: Reducing pollution while improving product yield and quality

In this paper, the effects and mechanisms of a novel two-step tomato peeling method, hot lye with a post-assistance of ultrasound, were investigated. The present work aims to improve the environmental friendliness of the conventional hot lye tomato peeling method (10% w/v, 97 °C, 45 s). The results showed that 4% (w/v) lye treatment at 97 °C for 30 s with a post-assistance of a 31.97 W/L ultrasound treatment at 70 °C for 50 s achieved a 100% peelability. In this scenario, the peeling yield and lycopene content in the peeled product were significantly higher than the peeling yield and lycopene content with the conventional hot lye peeling method. The present two-step peeling method was concluded with a mechanism of chemico-mechanical synergism, in which the hot lye functions mainly in a chemical way while the ultrasound is a mechanical process. Especially from the lye side, this work first demonstrated that the lye penetrated across the tomato skin via a pitting model rather than evenly. The findings reported in this paper not only provide a novel tomato peeling method with significant environmental benefits but also discover new clues to the peeling mechanism using hot lye.

OPTIMISATION OF LYE-PEELING OF CASSAVA (Manihot esculenta Crantz) USING RESPONSE SURFACE METHODOLOGY

Cassava (Manihot esculenta Crantz) is an important root crop in many tropical developing countries. Conventional peeling, done manually using knives is wasteful and unsuitable for industrial scale operation. Optimum condition for the peeling of cassava by immersion in hot lye (NaOH) solution was determined using Response Surface Methodology (RSM) for pre-determined three levels of Peeling Efficiency Index (PEI). Some cassava was peeled manually and some with hot lye solution. The effects of lye–concentration (4-12%), immersion temperature (75-100°C) and immersion time (2.5-10min.) on PEI (removal of 11-15% of root) obtained from 23 experimental points and three replication were analyzed with design expert and statistical analysis system software. Complete lye–peeling (removal of 11% of the root) was achieved at 9.7%, 86°C and 5min respectively which were within the critical optimization range (R 2 =43%, CV=44% and root mean square error 0.3935) generated by the RSM.

Peeling mechanism of tomato under infrared heating: Peel loosening and cracking

Critical behaviors of peeling tomatoes using infrared radiation heating are thermally induced peel loosening and subsequent cracking. Fundamental understanding of the two critical behaviors, peel loosening and cracking, remains unclear. This study aimed at investigating the mechanisms of peel separation for tomatoes subjected to a newly developed infrared dry-peeling process. Microstructural changes in tomato epidermal tissues under infrared heating were compared with those of fresh, hot lye and steam treated samples. Theoretical stress analyses coupled with the experimentally measured failure stress of tomato skin were combined to interpret the occurrence of peel cracking within a framework of elastic thin shell theory. With the use of light microscopy and scanning electron microscopy, it was observed that peel loosening due to infrared heating appeared to result from reorganization of extracellular cuticles, thermal expansion of cell walls, and collapse of several cellular layers, differing from samples heated by hot lye and steam. Crack behaviors of tomato skin were attributed to the rapid rate of infrared surface heating which caused the pressure build-up under the skin and strength decrease of the skin. In order to achieve a sufficient skin separation for effective peeling using infrared, promoting rapid and uniform heating on the tomato surface is essential. The findings gained from this study provide new insights for developing the sustainable infrared dry-peeling technology.

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.

Dry-peeling of Tomato by Infrared Radiative Heating: Part I. Model Development

Infrared (IR) dry-peeling of tomatoes has emerged as a nonchemical alternative to conventional peeling methods using hot lye or steam. Successful peel separation induced by IR radiation requires the delivery of a sufficient amount of thermal energy onto the tomato surface in a very short duration. The objective of this study was to understand the transient heat transfer phenomena during IR dry-peeling by developing a computer simulation model. Modeled tomatoes with realistic shapes and different sizes were employed to predict the temperature distributions on their surface and interior during a typical 60 s IR heating. IR radiation was postulated as a mathematically gray-diffuse radiation problem based on the enclosure theory. Radiation heat transfer model combining heat conduction and convection was solved numerically in COMSOL by using a finite element scheme. Changes of tomato thermal properties and phase change of water inside tomato tissues due to temperature increase were considered in the model to improve the prediction accuracy. The developed model can further be used to study the effects of various engineering parameters on IR heating performance relevant to tomato peeling quality and efficiency. Numerical modeling of the heat transfer mechanism provides in-depth understanding of the rapid surface heating characteristics of IR in the tomato dry-peeling process.

A comparison of dynamic mechanical properties of processing-tomato peel as affected by hot lye and infrared radiation heating for peeling

This study investigated the viscoelastic characteristics of tomato skins subjected to conventional hot lye peeling and emerging infrared-dry peeling by using dynamic mechanical analysis (DMA). Three DMA testing modes, including temperature ramp, frequency sweep, and creep behavior test, were conducted to evaluate the transition temperatures and dynamic moduli of tomato peels heated by infrared radiation and hot lye at four heating durations (30, 45, 60, and 75s). Fresh tomato peels were used as a control. Results showed that dynamic moduli of tomato peels were sensitive to temperature ramp and frequency sweep tests. Over a temperature range from 20°C to 100°C, transition temperatures of infrared treated peels (63–72°C) and lye treated peels (43–75°C) were significantly lower than those of fresh control (∼88°C). Values of both storage and loss moduli of infrared heated peels were considerably higher than those of the fresh control, whereas values of the storage and loss moduli from the lye peeled samples were lower than those of fresh peels. DMA tests effectively differentiated the viscoelastic behaviors of tomato peels and indicated mechanistic differences between the lye peeling and infrared dry-peeling.

Chemical, functional and nutritional properties of wet dehulled niger ( Guizotia abyssinica Cass.) seed flour

Niger seeds were dehulled using hot lye treatment. Dehulling of niger seeds increased the protein and fat contents from 24 to 35 and 31–53 g/100 g and decreased the crude fiber from 16.9 to 2.2 g/100 g, respectively. The defatted flour prepared from dehulled niger seeds was evaluated for chemical, functional and nutritional properties and compared to the undehulled flour. The protein content of the dehulled flour increased from 44 to 63 g/100 g. Dehulling resulted in inactivation of trypsin inhibitor activity. The dehulled flour had higher water and fat absorption capacities. However, the nitrogen solubility, emulsification capacity and foaming properties decreased. Chemical score of the dehulled flour was higher; threonine was the first limiting amino acid followed by lysine and isolecuine. The in vitro digestibility of the protein increased due to dehulling (85.5%) compared to that of undehulled flour (76%). The calculated nutritional indices, essential amino acid index, biological value, nutritional index and C-PER, were higher in dehulled flour compared to undehulled flour. The available lysine content appeared to be unchanged.

Effect of dehulling and heat processing on nutritional value of sesame proteins.

AbstractProcessing of edible sesame flour involves use of hot lye treatment of the seed for dehulling followed by drying, screw pressing, and solvent extraction. The effect of such processing on protein quality, especially lysine availability has been studied. The enzymatic digestibility of protein is improved as a result of dehulling, and lysine present in the flour exhibits remarkable stability to heat treatment, the maximum losses being less than 15% even under drastic conditions of heat treatment of the flour (1 kg/cm2 for 60 min). Supplementation of the flour with lysine at an optimal level of 1.25 g L‐lysine HCl/100 g flour enhances the nutritive value of protein, making it comparable to that of milk powder.

Sodium Sulfamerazine in the Treatment of Paratyphoid (S. Typhimurium) Infection in Pigeons: A Case Report

Squabs from 26 pairs of purebred fantail pigeons were affected with Salmonella typhimurium infection during the spring and summer breeding season of 1946. The mortality of the young birds when the survivors were three months of age was approximately 80 percent. Satisfactory hygienic conditions were maintained consistently in the loft where these birds were housed. Three unusually thorough cleanings of the loft and the equipment were made during the breeding season because of this infection. Hot lye solutions was used to scrub the feeders, roosts, nest boxes, floor, and walls of the loft. Most of the squabs that succumbed were between the ages of three to six weeks. The characteristic symptoms were sudden weakness and varying degrees of lameness in legs and/or wings; and swelling of the joints of the affected limbs frequently were observed. Post mortem examination of four birds revealed marked swelling and congestion of the liver and .

British Food Journal Volume 44 Issue 9 1942

British Food Journal Volume 44 Issue 9 1942

The effect of pretreatment and subsequent drying on the activity of grape oxidase

Abstract does not appear. First page follows. Thompson Seedless grapes usually darken during drying in the preparation of raisins. The intensity of this darkening depends to a considerable extent on the treatment of the fresh fruit prior to drying. Raisins prepared by drying grapes in the sunlight without other treatment are characteristically of a dark color similar to the clove-brown of (Ridgway (1912)).5 Raisins produced by the cold-dip, mixed-dip, soda-dip (hot lye), sulfur-bleach, or golden-bleach procedures, on the other hand, usually have a light color ranging in hue from cinnamon-buff to sepia as judged by the color standards of Ridgway. (Hussein and Cruess (1940)) investigated the properties of grape oxidase and suggested that oxidizing enzymes are involved to a considerable extent in the darkening of grapes during the preparation of raisins, and to some extent in the darkening of wines. These authors, however, limited their investigations to the enzyme preparation obtained from fresh, untreated grapes. There is no available published information concerning the effects of the various treatments used in the production of light-colored raisins on the oxidizing enzymes occurring in grapes. A series of experiments was conducted during the 1939 season in order to determine the effects of the mixed-, soda-, and cold-dip pretreatments, and of sulfuring and drying, on the oxidase activity of raisins made from Thompson Seedless grapes. Experimental Procedure Materials Used.—Thompson Seedless grapes were used in all experiments unless otherwise indicated. The sulfur-bleach and cold-, mixed-, and soda-dip procedures employed were similar to those in commercial use as described by (Mrak and Long (1941)). The golden-bleach procedure was similar to that used in the preparation of sulfur-bleach raisins, except that the fruit was dried in a dehydrater having a relative humidity of 25 per cent at the hot end, and a dry-bulb temperature of 71.1° C (160° F).