Susceptibility of 5-methyltetrahydrofolic acid to heat and microencapsulation to enhance its stability during extrusion processing

Folic acid is a common form of folate used for food fortification to prevent the incidence of neural birth defects among others. However, 5-methyltetrahydrofolic acid (5-MTHF) is considered, a better alternative to folic acid and is less likely to mask the symptoms of B₁₂ deficiency in older populations. Also it is less bioavailable, and present in very low amount in foods. Fortification of foods with 5-MTHF is considered problematic, because it is highly sensitive to normal food processing operations. A comparative study on the thermal stability of folic acid and 5-MTHF in various liquid model food matrices such as milk, soymilk, starch–water and water during boiling and autoclaving at various time intervals was performed. Thermal degradation of 5-MTHF was more severe than folic acid in all food matrices e.g., almost 70% loss of 5-MTHF vs 17% loss of folic acid. Microencapsulation of 5-MTHF is considered to improve the stability of 5-MTHF during processing. A combination of pectin (P) and sodium alginate (A) at three different proportions (P60:A40, P70:A30, P80:A20) were employed for encapsulating 5-MTHF by spray drying. Microcapsules with the highest loading efficiency of 60% of vitamin (from P80:A20) and unencapsulated 5-MTHF powder was incorporated into starch and extruded at six different temperatures (100, 110, 120, 130, 140, 150 °C). The 5-MTHF had better stability (84–94.5% retention) compared to the free form (65.3–83.2%) in all extruded products. The effectiveness of encapsulation was more evident at higher extrusion temperatures.     

Coconut water as a potential resource for cellulose acetate membrane preparation

BACKGROUND: Cellulose acetate membranes are frequently used for pressure‐driven membrane processes. The aim of this work was to prepare cellulose acetate membranes from nata‐de‐coco using coconut water as starting material. The use of this lignin‐free material will certainly minimize the use of chemicals usually needed in the traditional pulps and substitute for the use of wood, which helps prevent global warming and preserves nature as well. RESULTS: Coconut water was fermented by Acetobacter xylinum for 6 days to produce nata‐de‐coco, which was then acetylated to produce cellulose diacetate with an acetyl content of 39.6%. Fourier transform infrared analysis showed characteristic peaks for the acetyl group at 1748 and 1236 cm^?1. The resulting membranes made from the hydrolysis product showed a water flux of 210.5 L m^?2 h^?1 under an applied pressure of 2 kg cm^?2 while the rejection coefficients of dextran T‐500 and T‐2000 solutions were 78 and 93.7%, respectively. CONCLUSION: Coconut water has a potential to be used in the fabrication of membranes by converting it to nata‐de‐coco and then to cellulose diacetate which gives an added value to its original nature. It is also highly competitive compared to the traditional pulps, by which acetylation decreases the degree of crystallinity of nata‐de‐coco resulting in higher membrane permeability. Copyright © 2007 Society of Chemical Industry     

Extraction,transesterification and process control in biodiesel production from Jatropha curcas

Biodiesel has gained worldwide popularity as an alternative energy source due to its renewable, non‐toxic, biodegradable and non‐flammable properties. It also has low emission profiles and is environmentally beneficial. Biodiesel can be used either in pure form or blended with conventional petrodiesel in automobiles without any major engine modifications. Various non‐edible and edible oils can be used for the preparation of biodiesel. With no competition with food uses, the use of non‐edible oils as alternative source for engine fuel will be important. Among the non‐edible oils, such as Pongamia, Argemone and Castor, Jatropha curcas has tremendous potential for biodiesel production. J. curcas, growing mainly in tropical and sub‐tropical climates across the developing world, is a multipurpose species with many attributes and considerable potentials. In this article, we review the oil extraction and characterization, the role of different catalysts on transesterification, the current state‐of‐the‐art in biodiesel production, the process control and future potential improvement of biodiesel production from J. curcas.     

Physical and Processing Characteristics of Extrudates Made from Starch and d-Limonene Mixtures

In this study we examined the effect of d-limonene level of addition (0–0.5 g/100 g mixture) on the properties of starch processed through a twin screw extruder operated at different barrel temperatures (125–145°C). Limonene retention increased with increasing levels of addition, but was low overall (average recovery of 8.0%). The limonene level affected extruder torque and extrudate expansion ratio. Both decreased to a minimum at 3% d-limonene addition, but increased at higher levels of addition. The effect on extruder operation and extrudate properties was attributed to interaction between d-limonene and starch through the formation of inclusion complexes.     

Application of Microencapsulated Flavor to Extrusion Product

Flavoring is still a difficult problem in the snack food industry because of the high volatility of flavors and their instability under extrusion condition. Although postextrusion added flavor is commonly used, it suffers from numerous drawbacks. Flavor losses at the exit die because flash distillation is a critical issue and can only be minimized by controlling the pressure difference at the end of the barrel and the exit die, which, however, affects other desirable product characteristics. Residence time distribution (RTD), as an important intermediate process variable that among others controls the extent of reactions, can also be a major determinant on flavor retention during extrusion. Encapsulation of flavors is a promising alternative to enhance the retention of preextrusion added flavor during extrusion. The capsules should withstand high temperature and shear conditions in the extruder barrel. Various encapsulation techniques and their encapsulated flavor characteristics are illustrated.