Marleny D.A. Saldaña

Chemical Reactions in Food Systems at High Hydrostatic Pressure

The combination of high hydrostatic pressure and temperature has become a valuable alternative to produce superior quality products in cases where the traditional thermal treatments have failed to deliver high-quality products. Unfortunately, the impact of pressure on chemical reactions in food systems is often overlooked. This review summarizes studies on chemical reactions in various food systems that have been qualitatively and quantitatively evaluated under high pressure at either ambient, moderate, or elevated temperatures. In addition, a critical discussion on the current approaches was used to evaluate the reaction rates, and therefore, the reaction mechanisms of some food systems are provided. Activation volume and activation energy of various food systems treated by high hydrostatic pressure are also provided. Finally, the need of kinetic studies in food systems is highlighted.

Hydrolysis of sweet blue lupin hull using subcritical water technology

Hydrolysis of sweet blue lupin hulls was conducted in this study using subcritical water technology. Effects of process parameters, such as pressure (50-200 bar), temperature (160-220°C), flow rate (2-10 mL/min), and pH (2-12), were studied to optimize maximum hemicellulose sugars recovery in the extracts. Extracts were analyzed for total hemicellulose sugars, phenolics and organic carbon contents and solid residues left after treatments were also characterized. Temperature, flow rate, and pH had a significant effect on hemicellulose sugar removal; however, the effect of pressure was not significant. The highest yield of hemicellulose sugars in the extracts (85.5%) was found at 180°C, 50 bar, 5 mL/min and pH 6.2. The thermal stability of the solid residue obtained at optimum conditions improved after treatment and the crystallinity index increased from 11.5% to 58.6%. The results suggest that subcritical water treatment is a promising technology for hemicellulose sugars removal from biomass.

Pressurized aqueous ethanol extraction of β-glucans and phenolic compounds from waxy barley

Beta-glucans and phenolics were extracted from waxy barley using pressurized aqueous ethanol in a stirred batch reactor at 25bar and 500rpm. The effect of temperature (135-175°C), extraction time (15-55min) and ethanol content (5-20%) was evaluated. Temperature had an opposite effect on the extraction of both compounds. The higher the temperature, the lower the β-glucan extraction yield due to fragmentation, but a significant increase on the phenolic recovery was observed. Long extraction times favored the extraction of β-glucans at low temperatures and phenolics at any temperature. The ethanol content was not statistically significant on the β-glucan extraction, but helped to maintain the molecular weight of the extracted β-glucan. To obtain liquid extracts rich in high molecular weight β-glucans and phenolics, mild conditions of 151°C, 21min and 16% ethanol are needed, leading to 51% β-glucan extraction yield with a molecular weight of 500-600kDa and 5mgGAE/g barley.

Sulfated polysaccharide heparin used as carrier to load hydrophobic lappaconitine.

One-step self-assembly was used to prepare pH-sensitive lappaconitine-loaded low-molecular-weight heparin (LMWH-LA) and to demonstrate that the sulfur group promotes dissolution and has synergistic effect on the analgesic property of lappaconitine (LA). The LMWH-LA was characterized in terms of releasing behavior, pH-sensitivity, analgesic activity and anticoagulation property. The drug loading level of LA in low-molecular-weight heparin (LMWH) reached 24.3% (w/w). The LA, self-assembled in LMWH, released faster in an acidic environment than that in neutral or alkaline environments. Analgesic experiments showed that the LMWH-LA had earlier onset time and longer duration than the LA. Compared with LMWH, the LMWH-LA can reduce clotting time more effectively. These results suggest that the LMWH is a good template and has great potential to achieve synergistic effect of LA. In addition, similar macromolecular structure can be used as a new natural polymeric carrier for loading hydrophobic alkaloids.

Hydrophobic lappaconitine loaded into iota-carrageenan by one step self-assembly

New data on the loading of pH-sensitive lappaconitine loaded into iota-carrageenan (LA-ICG) is provided. This LA-ICG ionic biopolymer was prepared by one step self-assembly. The LA-ICG was characterized in terms of the loading capacity, lappaconitine (LA) releasing behavior, pH-sensitivity, and analgesic properties. Iota-carrageenan (ICG) high loading capacity reached up to 26.18% (w/w). Also, the LA, loaded with ICG, was released faster in an acidic environment than that in neutral or alkaline environments. Animal analgesic experiments showed that the LA-ICG of low molecular weight had earlier onset time and longer duration than the LA. These results suggest that the ICG of low molecular weight has great potential to achieve the synergistic effect of LA. In addition, the ICG can be used as a novel natural polymeric carrier for loading a hydrophobic alkaloid.

Combined effect of pressure-assisted thermal processing and antioxidants on the retention of conjugated linoleic acid in milk

The effect of pressure-assisted thermal processing (PATP) in combination with seven synthetic antioxidants was evaluated on the retention of conjugated linoleic acid (CLA) in enriched milk. Milk rich in CLA was first saturated with oxygen, followed by the addition of either catechin, cysteine, ascorbic acid, tannic acid, gallic acid, caffeic acid or p-coumaric acid (500 mg kg−1 untreated milk). Samples were treated at 600 MPa and 120 °C up to 15 min of holding time. During PATP, CLA not only oxidized at a slower rate, but also less oxygen was consumed compared to the control (0.1 MPa and 120 °C). In addition, phenolic antioxidants were able to quench dissolved oxygen in samples treated with PATP. For those samples added with gallic acid and catechin, 85% and 75% of the CLA was retained after 15 min of holding time at 600 MPa and 120 °C, respectively. The retention of CLA was enhanced by the application of PATP in combination with gallic acid.

Optimization of artemisinin extraction from Artemisia annua L. with supercritical carbon dioxide + ethanol using response surface methodology

Malaria is a high priority life‐threatening public health concern in developing countries, and therefore there is a growing interest to obtain artemisinin for the production of artemisinin‐based combination therapy products. In this study, artemisinin was extracted from the Artemisia annua L. plant using supercritical carbon dioxide (SC‐CO2) modified with ethanol. Response surface methodology based on central composite rotatable design was employed to investigate and optimize the extraction conditions of pressure (9.9–30 MPa), temperature (33–67°C), and co‐solvent (ethanol, 0–12.6 wt.%). Optimum SC‐CO2 extraction conditions were found to be 30 MPa and 33°C without ethanol. Under optimized conditions, the predicted artemisinin yield was 1.09% whereas the experimental value was 0.71 ± 0.07%. Soxhlet extraction with hexane resulted in higher artemisinin yields and there was no significant difference in the purity of the extracts obtained with SC‐CO2 and Soxhlet extractions. Results indicated that SC‐CO2 and SC‐CO2+ethanol extraction is a promising alternative for the extraction of artemisinin to eliminate the use of organic solvents, such as hexane, and produce extracts that can be used for the production of antimalarial products.

4.18 – Application of Supercritical Fluid Extraction in Food Processing

Over the past three decades, there has been an incredible amount of research and commercialization activity for the supercritical carbon dioxide (SC-CO 2 ) extraction of lipids, lipid-soluble components, as well as nutraceuticals from various matrices worldwide to generate ingredients for the functional food and nutraceutical product applications. This chapter provides an overview of the basic principles of supercritical fluid extraction and extraction equipment and operation at laboratory and industrial scales. In addition, a summary of the recent extraction studies is provided as well as current industrial applications worldwide. Indeed, thousands of studies have reported the extraction of various plant materials at the laboratory scale while few studies present data at the industrial scale. In addition to extraction, supercritical fluid technology offers numerous other possibilities in the inactivation of microorganisms in the food and beverage industry as well as delivery of bioactive components in the form of nano/micro-particles, which can be coupled with an extraction step.