Food & Function Blog

Scientists from Massey University, New Zealand, have investigated the physicochemical and microstructural changes of sodium caseinate-stabilized emulsions during lipid digestion in simulated gastric fluid (SGF) containing pepsin.

During passage through the gastrointestinal tract a food product passes through many different and complex environments from the mouth to the stomach and then to the intestine.  During this journey food will be exposed to widely different pHs, enzymes electrolytes and mechanical environments.  Model systems are thus used to understand such complex conditions because they allow the digestion behaviour and the interactions of individual physiological components of an emulsion to be investigated separately.

The milk protein casein is known to be easily hydrolysed because of its relatively open flexible structure and during digestion it may be hydrolysed by pepsin, which in turn may lead to changes under gastric conditions in the physicochemical properties of the emulsions. The emulsions can also undergo further change when they enter the small intestine.

In this study, the average size, size distribution, microstructure, proteolysis of interfacial proteins and lipolysis of the emulsion droplets were monitored as a function of digestion time. It was found that digestion in SGF accelerated the coalescence of emulsion droplets during simulated intestinal digestion. However, the changes in the size and the microstructure of the emulsions under gastric conditions did not appear to influence the rate and the extent of lipid digestion in the subsequent intestinal environment.

To read the full article, click the link below.  Free until 15th February:

Influence of gastric digestive reaction on subsequent in vitrointestinal digestion of sodium caseinate-stabilized emulsions, Jessie Li, Aiqian Ye, Sung Je Lee and Harjinder Singh, Food Funct., 2012, DOI: 10.1039/c2fo10242k

Also of interest and free to access:

Review of in vitro digestion models for rapid screening of emulsion-based systems
David Julian McClements and Yan Li, Food Funct., 2010, 1, 32-59, DOI: 10.1039/C0FO00111B

In human supplementation studies nuts have been shown to improve the lipid profile, increase endothelial function and reduce inflammation, all without causing weight gain.  They have a favourable fatty acid profile with low saturated fats and high PUFA which provides a rationale for the some of these effects, however, the benefits seen in these trials are greater than what would be predicted based on the amount and nature of fat consumed.  This suggests other bioactive constituents are present – but what are they?

Joe Vinson and Yuxing Cai have tested the hypothesis that the mystery bioactive compounds are polyphenols.  This hypothesis is supported by a body of work showing nuts have antioxidant capacity.

The team from the University of Scranton in the USA measured polyphenol levels in nuts and found that walnuts had the highest free and total polyphenols.  Furthermore, total polyphenols in the nuts was significantly higher than free polyphenols and roasting had little effect on the polyphenol levels.  The team also investigated the efficacy of nut antioxidants and showed that walnut extracts were superior in binding lower density lipoprotein and inhibiting its oxidation than other nuts.  However, all nuts are high in polyphenol antioxidants which by binding to lipoproteins inhibit oxidative processes that lead to atheroscelrosis in vivo.

Finally, the team then used their findings on polyphenol levels in nuts and per capita consumption data to calculate the contribution of nuts to the daily antioxidant intake in the US diet.  They show that nuts represent 19% of the food and beverage polyphenols in the average US diet.

Interested in knowing more?  Read the full article for free until the end of January 2012.

Nuts, especially walnuts, have both antioxidant quantity and efficacy and exhibit significant potential health benefits
Joe A. Vinson and Yuxing Cai
Food Funct., 2012, Advance Article, DOI: 10.1039/C2FO10152A

Scientists from Canada have investigated b-carotene release from lipid nanodispersions under simulated gastrointestinal conditions. Enhancing the health benefits of food by incorporating bioactive molecules (such as b-carotene) is of increasing interest as it may help with chronic conditions. The bioactives can be incorporated into the food matrices by designing oil-in-water emulsions.

In this work, the influence of interfacial structure of solid lipid nanoparticle dispersions and oil-in-water emulsions containing encapsulated b-carotene  were examined under simulated gastrointestinal conditions. It was found that the uptake of lipolytic products and lipophilic bioactives depended on nonionic surfactant type, the extent of lipid digestion, as well as the presence of bile salts and phospholipids.

This work was presented at the Delivery of Functionality in Complex Food Systems Symposium held in Guelph in August 2011, and is part of our themed issue on the Delivery of Functionality coming soon in 2012. The article is free to access until the end of 2011, to read it in full click the link below:

Digestibility and b-carotene release from lipid nanodispersions depend on dispersed phase crystallinity and interfacial properties, Amir Malaki Nik, Sarah Langmaid and Amanda J. Wright, Food Funct., 2012, DOI: 10.1039/c1fo10201j

Scientists in Germany have investigated the effects of encapsulating polyphenolic grape seed extract in liposomes. Grape seed extract contains polyphenols which can reduce the extent of oxidative processes in organisms, and hence may be a beneficial food for chronic diseases such as cancer, diabetes mellitus and cardiovascular disease.

Phenolic compounds are, however, difficult to incorporate into food systems because they can strongly interact with other compounds and cause aggregation. By encapsulating the polyphenols they are protected and this may prevent them from being degraded during digestion, thereby enhancing their bioactivity and bioavailability.

In this work, coated liposomes containing grape seed extract were prepared by using chitosan and citrus pectin polymers.  The amount of polyphenols that reacted in the antioxidant test was decreased, suggesting that the polyphenols were no longer exposed to the aqueous phase. This indicates that polymer coated liposomes are highly capable carrier systems for polyphenol compounds.

This work was presented at the Delivery of Functionality in Complex Food Systems Symposium held in Guelph in August 2011, and is part of our themed issue on the Delivery of Functionality coming soon in 2012. To read the full article for free, please follow the link below:

Encapsulation of polyphenolic grape seed extract in polymer-coated liposomes, Monika Gibis, Effie Vogt and Jochen Weiss, Food Funct., 2012, DOI: 10.1039/c1fo10181a

Other articles from this conference have recently been published as Advance Articles in Food & Function. Click the following links to read Potential biological fate of ingested nanoemulsions: influence of particle characteristics and Fibrillar structures in food

Scientists in Taiwan and the US have investigated the effects of garcinol and pterostilbene on cell proliferation and adipogenesis in 3T3-L1 cells. Antiadipogenic compounds are important compounds for the control of obesity as they inhibit the formation of fatty tissues. By controlling obesity this can also mediate other health problems associated with the condition, such as type 2 diabetes, cardiovascular disease and cancer.

In this study, 3T3-L1 preadipocytes, 3T3-L1 differentiation- phase adipocytes, and mature 3T3-L1 adipocytes were used to investigate antiproliferation and adipogenesis in vitro. It was found that garcinol, a benzophenone found in mangosteen, and pterostilbene commonly found in grapes, wines and berries, both inhibit cell proliferation and adipogenesis in 3T3-L1 cells. Garcinol also significantly up-regulated the gene expression of adiponectin as well as down-regulated the gene expressions of leptin and fatty acid synthase. This suggests that garcinol and pterostilbene have anti-adipogenic effects on fat cells.

To read the free article in full, click the link below:

Inhibitory effects of garcinol and pterostilbene on cell proliferation and adipogenesis in 3T3-L1 cells, Chin-Lin Hsu, Yu-Jyun Lin, Chi-Tang Ho and Gow-Chin Yen, Food Funct., 2011, DOI: 10.1039/c1fo10209e

Scientists from the US have investigated the relationship between the Taq1 A1 allele and percentage of body fat in overweight and obese subjects. Although there are many environmental factors which can reduce body fat, such as long-duration exercise, aerobic exercise and diet, it has been proposed that genetics may play a significant role in compulsive eating disorders.

In this study 122 obese/overweight Caucasian subjects and 30 non-obese Caucasian controls were genotyped and split into two independent groups; those with the Taq1 A1 allele and those without the A1 allele. It was found that the DRD2 Taq1 A1 allele was present in 67% of the obese/overweight subjects compared to 3.3% of super control group. Therefore it is proposed that, while obesity is a polygenic disorder and there are other factors involved,  the DRD2 gene plays a significant role in obesity, as measured by percent body fat.

To read the article in full for free, click the link below.

Correlation of the Taq1 dopamine D2 receptor gene and percent body fat in obese and screened control subjects: A preliminary report, Amanda L. C. Chen, Kenneth Blum, Thomas J. H. Chen, John Giordano, B. William Downs, David Han, Debmalya Barh and Eric R. Braverman, Food Funct., 2011, DOI: 10.1039/c1fo10089k

Scientists from Ehime, Japan, have investigated the effects of (–)-secoisolariciresinol on obese rats. (–)-Secoisolariciresinol [(–)-SECO] is a pure stereoisomer of a lignan primarily found in flaxseed. It has previously been found to suppress triglyceride accumulation and therefore could be useful to decrease obesity by reducing fat accumulation.

In this study, male mice were fed a high fat diet for 28 days and different groups were administered with (–)-SECO at different concentrations. It was shown that oral administration of (–)-SECO stimulates adiponectin production in the mice and significantly suppressed weight gain in a dose dependant manner. When (–)-SECO is metabolised, it is converted into other compounds which were also tested by subcutaneous injections, however (–)-SECO still showed the highest activity amongst them.

Follow the link below to read the article for free:

(–)-Secoisolariciresinol attenuates high-fat diet-induced obesity in C57BL/6 mice, Shiori Tominaga, Kosuke Nishi, Sogo Nishimoto, Koichi Akiyama, Satoshi Yamauchiad and Takuya Sugahara, Food Funct., 2011, DOI: 10.1039/c1fo10166h

There is increasing evidence to show that dietary fatty acids play an important role in modulating hypertriglyceridemia in the postprandial state, which contributes to the pathogenesis of type 2 diabetes, atherosclerosis, coronary heart disease and stroke. In this review, by Francisco Muriana and colleagues, the potential of dietary monounsaturated fatty acids (MUFA), polyunsaturated fatty acids (PUFA), and saturated fatty acids (SFA) to postprandially affect metabolic abnormalities related to chronic diseases is discussed.

It is highlighted that consuming a high fat diet rich in SFA could increase the risk of developing chronic diseases such as obesity, diabetes, hypertension and cardiovascular disease. Consuming MUFA, primarily found in olive oil, leads to improved lipid tolerance and insulin action, whereas PUFA offers no additional benefits over MUFA.

To read the article in full for free, click the link below:

Dietary fatty acids linking postprandial metabolic response and chronic diseases, Almudena Ortega, Lourdes M. Varela, Beatriz Bermudez, Sergio Lopez, Rocio Abia and Francisco J. G. Muriana, Food Funct., 2011, DOI: 10.1039/c1fo10085h

Scientists in Australia have investigated the intestinal passage of fish oil using radio labelling to track free or microencapsulated fish oil . Fish oil is of great interest due to its many beneficial health effects, which have been attributed to its high level of long chain n-3 polyunsaturated fatty acids.  The bioavailability of oils depends on many factors including their state of emulsification and whether they are delivered in the presence of food.

In this work, Mary Ann Augustin and co-workers compare the oral delivery of free (oil-water mixture) or microencapsulated (oil-in-water emulsion formulation) fish oil to rats, which were then either fed or were not fed after dosing. This was to establish whether access to food after dosing affects the release of the oil. It was observed that feeding after administration of oils increases the rate of progress of oil through the lumen and that microencapsulation delays the lumenal progression of oil in fed rats. Delivery via microencapsulated oil also resulted in increase in the level of radiolabel in the liver and blood which is consistent with an increased bioavailability of microencapsulated oil.

To read the article in full for free, click the link below:

Intestinal passage of microencapsulated fish oil in rats following oral administration, Mary Ann Augustin, Glen Patten, Anthony De Luca, Mahinda Abeywardena, Trevor Lockett, Richard Head and Luz Sanguansri, Food Funct., 2011, DOI: 10.1039/c1fo10149h