Subcritical water extraction of bioactive compounds from plants and algae: applications in pharmaceutical and food ingredients

Plants and algae are the main sources of natural bioactive compounds used in the food and pharmaceutical industries. It is very important to achieve an efficient and safe technique to recover bioactive compounds while maintaining their quality and properties. Subcritical water extraction is the most promising engineering approach that offers an environmentally friendly technique for extracting various compounds from plants and algae. Application of pressurized water and high temperature in subcritical phase is able to modify the dielectric constant and polarity of the solvent which then contributes to a better extraction process. The technique improves the mass transfer rate and preserves the biological potency of the extracts. This article reviews current studies on the extraction of bioactive compounds from various species of plants and algae using the subcritical water technique and discusses its effects and benefits for the food and pharmaceutical industries

Optimization of protein extraction from fish waste using Response Surface Methodology

The aim of present study was to optimize protein extraction from Fish Waste (FW), sardine (Sardina pilchardus) using enzymatic method. In this study, enzymatic method involved two combinations of enzymes which were alcalase and protamex. Response Surface Methodology (RSM) was used to study the effect of independent variables, namely temperature (35-55°C), rotation speed (100-300 rpm), time (60-1440 min) and enzyme:substrate ratio (0.5-1.5) on protein extraction from FW. From RSM-generated model, the optimum conditions for extraction of protein from FW were identified to be at temperature 35°C in 1429 min reaction time, with rotation speed of 171 rpm and enzyme:substrate ratio of 1.50. At the optimum conditions, predicted protein yield in the extraction process was 80.75 mg mL-1

Optimization of protein extraction from freeze dried fish waste using response surface methodology (RSM)

The present study embarked on the objective of optimizing protein extraction from freeze dried fish waste (FD-FW), sardine (Sardina pilchardus). Introduction of freeze drying prior to extraction was aimed at reducing the risk of protein loses in fish waste (FW) during frozen storage before the extraction process. Response surface methodology (RSM) was used to study the effect of independent variables, namely time (30-60 minutes), pH (7-11), rotation speed (100-300 rpm), and NaOH: substrate ratio (1-3) on protein extraction from FD-FW. From RSM-generated model, the optimum conditions for extraction of protein from FD-FW were identified to be at pH 10.56 in 48.61 minutes reaction time, with rotation speed of 104.77 rpm and NaOH: substrate ratio of 1.54. Predicted protein yield was 85.02 mg/ml while an experimental protein yield was 83.51 mg/ml as revealed by confirmatory studies

Removal of lactose from highly goat's milk concentration through ultrafiltration membrane

Concentration of goat milk using cross-flow filtration unit with 10KDa molecular weight cut off (MCWO)-sized ultrafiltration membrane was examined under various operating conditions. The parameters to be optimized are trans-membrane pressure (TMP) and cross-flow velocity. Permeate flux is decreased with time due to fouling of the membrane. The localized membrane fouling may be reduced by increasing the feed flow rate and TMP to mitigate overall membrane fouling. By doing so, the transmission of lactose will also increase. The aim is to produce concentrated goat milk with minimal lactose content and thus high concentration of protein. Spray-drying method is used to convert the concentrated non-lactose milk obtained into milk powder. The milk powder then was characterized in terms of its surface particle, solubility, and nutritional content with the well-commercialized non-lactose milk. This project tackles understanding to minimize the deposition rates of particles on membrane by optimizing the involved parameters and be proved by comparing the yield obtained with well-commercialized non-lactose milk

Separation of lactose from raw goat's milk by cross-flow hollow fiber ultrafiltration membrane

An extensive amount of research has reported on the use of ultrafiltration (UF) membrane, particularly in the improvement of membrane performance efficiency on cow’s milk. However, a very limited number of researches reported on using UF for producing low-lactose goat’s milk due to inherently low lactose. Nonetheless, goat’s milk is still not suitable to be consumed in a large amount by people who are lactose intolerant, especially among Asians, where over 90% of the populations are suffering from lactose intolerance. Until today, fouling and concentration polarization (CP) on membrane surface in cross-flow hollow fiber UF unit are the major problems in the dairy industry. Discovery on how to overcome the problem is still in a hot debate due to the nature’s complex composition in milk. One way to overcome this problem is by evaluating the effects of processing parameters such as trans-membrane pressure (TMP) and feed-flow rate on flux (J), lactose rejection (Ri), concentration factor (CF), and accumulation rate (AR) during the fractionation of lactose. In terms of lactose fractionation for 5 KDa and 10 KDa UF membranes, the TMPs examined were 0.41, 0.55, and 0.69 bars, while feed flow-rates examined were 0.18, 0.34, 0.54, and 0.74 L/min. 5 KDa membrane shows that feed flow-rate and flux behave in a direct relationship, while an inverse relationship in 10 KDa membrane. Both membranes showed that TMP 0.55 bar exhibit the best flux value without reaching the limiting flux region, but with feed flow rate of 0.74 L/min in 5 KDa, while 0.18 L/min in 10 KDa membrane. Lactose rejection percentage (%Ri) is the lowest with 77.71% in 5 KDa membrane while 66.28% in 10 KDa membrane. This can be summarized that the best parameters for 5 KDa membrane is at TMP 0.55 bar with feed flow-rate of 0.74 L/min, while for 10 KDa membrane is at TMP 0.55 bar with feed flow-rate of 0.18 L/min. Due to higher flux value and lowest lactose rejection obtained from low feed flow-rate, 10 KDa UF membrane size was chosen over 5 KDa. As a conclusion, a high degree of lactose removal from goat’s milk could be achieved by 10 KDa UF membrane in a cross-flow hollow fiber system, which proved that different outcomes between 5 KDa and 10 KDa membranes and feed flow-rate required is closely associated to UF pore size and molecular weight of feed solute particles

Xylitol biological production: a review of recent studies

Xylitol is an alternative sweetener that is recommended for use in food and pharmaceutical products, as it has some health benefits. It is currently produced on a large scale using a chemical reduction that requires high energy and is costly. Biological conversion of xylitol using microorganisms is an alternative process that is environmentally friendly and cost-effective. This process has been studied in an effort to provide one that is high yielding and competitive with chemical processes. This article reviews recent studies in the development of biological conversion processes for the production of xylitol, including biomass conversion, fermenting microorganisms, and new technology for full-scale process development

Overliming effects on xylitol production from sago trunk hydrolysate

Xylitol can be obtained from lignocellulosic materials containing xylose. However, the fraction of lignocellulose converted through dilute acid hydrolysis contains compounds that inhibit the fermenting micro-organisms. These inhibitors can be removed from the hydrolysate by detoxification method, prior to fermentation. This study describes effectiveness of overliming process to reduce the toxicity of hydrolysates generated from pre-treatment of sago trunk for xylitol production. The overliming pH 9 and 10 was studied and the results showed that pH 9 was showed 20% of sugar loss, which is low compared to pH 10. Candida tropicalis strain was used to evaluate the fermentability of overlimed sago trunk hydrolysate at pH 9 and non-overlimed hydrolysate medium. Meanwhile, Xylitol accumulation and productivity in the overlimed medium was found to be higher than the non-treated medium. The maximum production of xylitol was increased up to 74% and converted within 76 h. The results obtained improved the fermentation process when compared with the non-treated medium

Evaluation of Fermentation Conditions by Candidatropicalis for Xylitol Production from Sago Trunk Cortex.

Xylitol production from sago trunk cortex hydrolysate using Candida tropicalis was evaluated in shake flasks and a bioreactor. The fermentation and kinetic behaviours of this microorganism were investigated using sago trunk cortex hydrolysate and commercial xylose as substrate. Results obtained for sago trunk hydrolysate were close to the commercial xylose with xylitol yield of 0.82 gg-1 and productivity of 0.39 gL-1h-1. The maximum specific growth rate, µmax for sago trunk cortex was higher (0.24 h-1) compared to commercial xylose (0.17 h-1). The bioreactor study showed an increase of about 6% (w/v) of xylitol concentration and 10% (v/v) of volumetric productivity when compared to the results obtained under the shake flasks, keeping xylitol yield above 0.8 g g-1

Optimization of xylose production from sago trunk cortex by acid hydrolysis

Sago trunk cortex is a renewable source for the production of many useful products, such as xylose and xylitol. The potential of bioconversion xylose to xylitol from sago trunk cortex is justifiable as these materials are cheap and widespread sugar sources. Lignocellulose type of residue such as sago trunk cortex structure can break to their monomeric sugars with hydrolysis process. Various hydrolysis temperature and acid concentration at constant temperature were investigated to evaluate the potential maximum xylose concentration in the sago trunk hydrolysate. The objectives of this study were to determine the composition of sago trunk cortex and the effects of sulphuric acid (H2SO4) concentration and hydrolysis time on the production of xylose from sago cortex waste. Response surface methodology (RSM) based on central composite design (CCD) was used to optimize the hydrolysis conditions in maximizing the xylose concentration. The optimum hydrolysis time and acid concentration found were 60 min and 8%, respectively. Under these conditions, the xylose concentration achieve was 22.78 g/l. The study provides efficient analysis on optimizing xylose concentration, in order to obtain higher productivity and yield of xylitol

Development of an integrated grating and slicing machine for starchy vegetables

Processed foods usually undergo one or several unit food processing operations before becoming the final products. Many food processing equipments were developed to perform more than one operation in food processing by providing practical purposes that further enhance their performance. However, conventional processes of grating and slicing that produce grated and sliced food products normally involved two units of independent operation machines. Therefore in this study, grating and slicing processes have been combined into a single operation through an integrated machine for simultaneous grating and slicing operations. The purpose of integrating both grating and slicing processes is to increase productivity through the reduction of cost, time and the number of unit operations, which are involved in the processing system of grating and slicing production. The machine’s design specifications were identified to ensure that simultaneous grating and slicing operations in an integrated machine are capable to process the raw materials (starchy vegetables) simultaneously for grated and sliced outputs. A final machine design was generated by following a product development process as the research method. The design process steps starts from planning, concept development, detail design and machine fabrication, testing and refinement. The final design of the machine (at present) shows that it is suitable for use in industrial processing level which the output rate is powered at 750 W with variable speed of 0 – 180 rpm, grated and sliced production range of 750 – 1200 kg/h and 250– 400 kg/h, respectively. This newly designed machine is easy to setup, handle, store, clean, service and maintain. The design of an integrated grating and slicing machine will express a better understanding on the machine capability to reduce cost and energy for simultaneous grating and slicing processes with increased productivity