Food & Function Blog

Jianshe Chen and co-workers from the University of Leeds, UK, have developed a simple model device for routine investigation of in vitro gastric digestion.  Knowledge of food disintegration in the human stomach is essential for assessing the bioavailability of nutrients.  Studies in medicine, pharmacy and clinical nutrition have demonstrated that disintegration of food and drugs inside the stomach is a highly complicated process.  Food is broken down into small particulates and molecules as a result of both physical forces and chemical reactions; it is extremely difficult to mimic stomach conditions in vitro.

Although some very sophisticated in vitro digestion devices have been developed they are not suitable for routine use due to their complexity.  In this study, the UK Food Scientists describe a simple in vitro digestion device.  The device is housed in a water-jacketed glass vessel which has a constant flow around it to maintain body temperature.  A spherical Teflon probe of variable diameter can be inserted which is controlled by a texture analyser and moved up and down to simulate the kinetics of a food digestion process.  A schematic of the device is shown in the image to the right.

Under well controlled hydrodynamic flow and biochemical conditions this device can be used to determine key digestion parameters such as pH, food particle size, protein release, lipid release, cloudiness etc. Feasibility tests of the model device were conducted using roasted and non-roasted peanut particles; after digestion significant differences of surface microstructure were observed (see figure to left).  The study also showed that parameters such as food to gastric juice ratio, probe speed and pepsin concentration all influenced the kinetic process of gastric digestion and need to be well regulated in any in vitro digestion investigation.

This device has the advantages of easy control and operation and can be an ideal tool for routine in vitro gastric digestion studies.

Interested in knowing more?  Read the full text here.

Development of a simple model device for in vitro gastric digestion investigation
Jianshe Chen, Vishwajeet Gaikwad, Melvin Holmes, Brent Murray, Malcolm Povey, Ye Wang and Ying Zhang
Food Funct., 2011, Advance Article
DOI: 10.1039/C0FO00159G

A team from India has shown that an edible blue-green algae Spirulina laxissima can protect the liver against CCl₄ induced oxidative damage in rats.

Spirulina species have been used as food for thousands of years and many medicinal properties have been attributed to them such as weight and cholesterol reduction and radical-scavenging action.  Spirulina is also an important source of the blue photosynthetic pigment phycocyanin (PC), which has been described as a strong antioxidant and anti-inflammatory natural compound.  Carbon tetrachloride (CCl₄) is a well-known hepatotoxic agent. The changes associated with CCl₄-induced liver damage are similar to those of acute viral hepatitis and CCl₄-induced liver damage is a classic model used for the screening of hepatoprotective drugs.

The ethanol extract of Spirulina laxissima (EESL) was used in experiments as it was demonstrated to have the greatest antioxidant properties compared to methanol and water extracts.  In this study EESL was dosed an hour before CCl₄ and the treatments were administered to rats 3 times a week for 5 weeks.  A variety of markers were used to assess liver function after this period; protein and antioxidant levels in the liver as well as liver function marker enzymes. Treatment with CCl₄ resulted in liver damage in all parameters tested, but treatment with EESL before CCL₄ treatment reduced the hepatotoxic effects of CCl₄.

This study, by Gini C. Kuriakose and Muraleedhara G. Kurup, demonstrates the hepatoprotective and antioxidant properties of the ethanol extract of S. laxissima (EESL). The authors suggest that the hepatoprotective effect of EESL may be due to the presence of phycocyanin pigment however further studies are needed to identify and isolate the active principles of EESL.

Interested in knowing more?  Read the full article here!

Antioxidant and antihepatotoxic effect of Spirulina laxissima against carbon tetrachloride induced hepatotoxicity in rats
Gini C. Kuriakose and Muraleedhara G. Kurup
Food Funct., 2011, Advance Article
DOI: 10.1039/C0FO00163E

All articles in Food & Function are free for the duration of 2011!

A team from the Central Food Technological Research Institute in India has identified the expression pattern of carotenoid biosynthetic pathway genes during tomato ripening.  Their results may provide insight into devising gene-based strategies for enhancing carotenoid accumulation in tomato fruits.  This has significance because consumption of fruit and vegetables, especially tomatoes, has been linked with a reduced risk of cancer in epidemiological studies: evidence increasingly suggests that this is due to the antioxidant effect of carotenoids. 

The ripening of tomato fruit is a highly regulated process during which co-ordinated genetic and biochemical events take place leading to changes in fruit texture, aroma, colour and flavour.  One of the most important and noticeable changes during ripening is the change in pigmentation due to a massive accumulation of the bright red carotenoid lycopene.

In this study, Singh Negi and co-workers investigated the expression of carotenoid biosynthetic pathway genes and the lycopene content at different stages of maturity in tomato fruit.  The results revealed that there was an increase in the levels of upstream genes of the carotenoid biosynthetic pathway 5 days before lycopene content peaked.  Lycopene accumulation also coincided with the colour values at different stages of maturity. This complete gene expression analysis could inform strategies for enhancing the accumulation of lycopene in tomatoes, thus increasing their potential health benefits.

Interested in knowing more? Read the full article here!

Expression of carotenoid biosynthetic pathway genes and changes in carotenoids during ripening in tomato (Lycopersicon esculentum)
Kanakapura Krishnamurthy Namitha, Surya Narayana Archana and Pradeep Singh Negi
Food Funct., 2011, Advance Article
DOI: 10.1039/C0FO00169D