Concentration of apple juice using CO2 gas hydrate technology to higher sugar contents

Experimental Kinetic Evaluation of Carbon Dioxide Hydrate-Based Concentration for Grape, Pineapple, and Bitter Melon Juices

Hydrate-based technology has emerged as a promising approach to address the industry's energy demands and product quality challenges in the food industry. Despite reported successes in the literature where higher dehydration ratios were achieved, technological problems like slow formation rates and poor process scale-up economics need to be addressed. Moreover, with little hydrate formation data available, the major focus is on the technology's ability to remove water content, but studies on the kinetics of hydrate formation are scarce. In the present work, the effects of varying grape/pineapple/bitter melon juice water cuts (88.5 to 97.4 ± 2.53 wt %) on the formation kinetics of carbon dioxide (CO₂) hydrates were investigated. Such information can provide insight into the possibile commercialization of the hydrate-based technology. The reported experimental data were determined using the isochoric pressure-search method in a high-pressure reactor at a target initial temperature from 274.15 to 276.15 K and varying initial pressures. Kinetic parameters were calculated using the relative kinetic models proposed in the literature. Lower relative values of investigated kinetic parameters and longer induction times were obtained at lower juice water cuts and lower degrees of subcooling. Despite observed inhibition effects, the study provides useful experimental and modeled kinetic data for filling the knowledge gap in understanding the controlling mechanism of CO₂ hydrate formation. Therefore, it is believed that the reported findings may highlight some important practical aspects related to CO₂ hydrate technology as an alternative juice concentration process.

An Innovative Approach in the Baking of Bread with CO2 Gas Hydrates as Leavening Agents

Gas (guest) molecules are trapped in hydrogen-bonded water molecules to form gas hydrates (GH), non-stoichiometric solids that resemble ice. High pressure and low temperature are typical conditions for their development, with van der Waals forces joining the host and guest molecules. This article study investigates the application of CO₂ gas hydrates (CO₂ GH) as a leavening agent in baking, with particular reference to the production of wheat bread. The main intention of this study is to better understand the complex bread dough formed by CO₂ GH and its impact on product quality. This may enable the adaptation of CO₂ GH in baking applications, such as those that can specifically influence wheat bread properties, and so the final bread quality. The present research further examines the comparative evaluation of yeast bread with the GH bread's impact on bread quality parameters. The amount of GH was varied from 10 to 60%/amount of flour for the GH breads. The GH breads were compared with the standard yeast bread for different quality parameters such as volume, texture, and pore analysis. The results show that the bread with 20% and 40% GH obtained the best results in terms of volume and pore size. Moreover, this article also sheds some light on the future applications of the use of CO₂ GH as leavening agents in foods. This knowledge could help to create new procedures and criteria for improved GH selection for applications in bread making and other bakery or food products.

Experimental Hydrate Phase Equilibrium Data Relevant to Bitter Melon, Pineapple, and Grape Juice Concentration

One of the major challenges experienced by the fruit juice industry is the steady rise in energy costs. Hence, it is of industrial interest to find possible environmentally friendly measures that reduce energy consumption while cost-effectively maintaining the quality of manufactured products. Hydrate-based juice concentration technology can be used to overcome this challenge. In the present work, experimental hydrate phase equilibrium conditions of three systems involving juices (system 1, CO₂ + grape juice; system 2, CO₂ + pineapple juice; system 3, CO₂ + bitter melon juice) were measured using an isochoric pressure search method. The temperature and pressure ranges for reported experimental data were 272.6-282.3 K and 1.17-3.85 MPa, respectively. Results have shown that a decrease in water cut from 98.3 to 88.5 ± 2.53 wt % could shift the hydrate phase equilibrium conditions toward higher pressures and lower temperatures. This proved that all investigated juices exhibited inhibitory effects on gas hydrate formation. To properly assess the energy requirements for this novel technology, molar hydrate dissociation enthalpies were estimated using the Clausius-Clapeyron relations under different measurement conditions. Finally, it was established that a hydrate-based fruit juice concentration technology would be a credible alternative to existing commercial technologies, on the basis of the dehydration ratio of 57% obtained in the present study.

Experimental investigation of CO2 uptake in CO2 hydrates formation with amino acids as kinetic promoters and its dissociation at high temperature

The dissociation of CO₂ gas hydrates (GH) with amino acid kinetic promoters and without promoters was studied at a high temperature of 90 °C for a period of 20 min to understand the percentage of CO₂ gas and to select the best promoter that aids CO₂ gas entrapment along with stability at a high temperature. The possibility of using four hydrophobic food grade amino acids, namely cysteine, valine, leucine, and methionine, and one surfactant, lecithin, as kinetic promoters for CO₂ GH has been studied. The amino acids were added 0.5 g (wt%), and lecithin was added 5 g for the GH production. Furthermore, the amino acids leucine and methionine gave some positive results, therefore, these amino acids were carried further for the experimentation purpose in the production of CO₂ GH. Also, a combinational use of these amino acids was studied to investigate the effect on % CO₂ retention in comparison to the normal GH. From the results, it was observed that the stability of GH decreases with an increase in temperature, but the addition of promoters, especially leucine + methionine + lecithin increased the CO₂ uptake during GH formation.

A Future Road Map for Carbon Dioxide (CO2) Gas Hydrate as an Emerging Technology in Food Research

Gas hydrates constitute of gas as a guest molecule in hydrogen-bonded water lattices. This review covers ongoing hydrate research in food technology with a spotlight on carbon dioxide (CO2) application as a hydrate. The application of gas hydrates in the concentration of juices, desalination, carbonation, and food preservation has been covered in the review. One of the applications of CO2 hydrate technology was in the concentration of orange juice which gave a dehydration ratio (DR) of 57.2% at a pressure of 4.1 MPa. Similarly, one study applied it for the tomato juice concentration and had a DR of 65.2%. The CO2 hydrate rate constants recorded were 0.94 × 10−8 and 1.65 × 10−8 J−1 mol2 s−1 at a feed pressure of 1.81 and 3.1 MPa respectively. Hence, CO2 hydrate can be used effectively for the juice concentration as well as for other applications too. The review will cater insights on the generic trends of hydrates in food research with respect to their kinetics properties and their role in food applications. Despite the fact that there are no technology stoppers to exploit CO2 hydrates, a downright technological quantum leap is the need of the future in this riveting field. Thus, the perspectives and key challenges in food research are also discussed. The food applications of CO2 gas hydrates are still very scarce so there is an urge to carry through more theoretical and experimental analysis to elucidate various applications of hydrates in food and to positively validate its sustainability.

Concentrating Model Solutions and Fruit Juices Using CO2 Hydrate Technology and Its Quantitative Effect on Phenols, Carotenoids, Vitamin C and Betanin

Fruits have an important economic impact in the context of plant-based food production. The consumption of fruit juices, mostly produced from concentrates, is particularly noteworthy. Conventional concentration methods do not always enable a sustainable and gentle concentration. The innovative gas hydrate technology addresses this point with its energy-saving, gentle character, and high concentration potential. In this study, the concentration of fruit juices and model solutions using CO2 hydrate technology was investigated. To find a suitable operating point for hydrate formation in the used bubble column, the hydrate formation in a water–sucrose model solution was evaluated at different pressure and temperature combinations (1, 3, 5 °C and 32.5, 37.5, 40 bar). The degrees of concentration indicate that the bubble column reactor operates best at 37.5 bar and 3 °C. To investigate the gentle processing character of the hydrate technology, its quantitative effects on vitamin C, betanin, polyphenols, and carotenoids were analyzed in the produced concentrates and hydrates via HPLC and UV/VIS spectrophotometry. The results for fruit juices and model solutions imply that all examined substances are accumulated in the concentrate, while only small amounts remain in the hydrate. These amounts can be related to an inefficient separation process.