In vitro evaluation of the prebiotic activity of a pectic oligosaccharide-rich extract enzymatically derived from bergamot peel

The prebiotic effect of a pectic oligosaccharide-rich extract enzymatically derived from bergamot peel was studied using pure and mixed cultures of human faecal bacteria. This was compared to the prebiotic effect of fructo-oligosaccharides (FOS). Individual species of bifidobacteria and lactobacilli responded positively to the addition of the bergamot extract, which contained oligosaccharides in the range of three to seven. Fermentation studies were also carried out in controlled pH batch mixed human faecal cultures and changes in gut bacterial groups were monitored over 24 h by fluorescent in situ hybridisation, a culture-independent microbial assessment. Addition of the bergamot oligosaccharides (BOS) resulted in a high increase in the number of bifidobacteria and lactobacilli, whereas the clostridial population decreased. A prebiotic index (PI) was calculated for both FOS and BOS after 10 and 24 h incubation. Generally, higher PI scores were obtained after 10 h incubation, with BOS showing a greater value (6.90) than FOS (6.12).

In vitro determination of prebiotic properties of oligosaccharides derived from an orange juice manufacturing by-product stream

Fermentation properties of oligosaccharides derived from orange peel pectin were assessed in mixed fecal bacterial culture. The orange peel oligosaccharide fraction contained glucose in addition to rhamnogalacturonan and xylogalacturonan pectic oligosaccharides. Twenty-four-hour, temperature- and pH-controlled, stirred anaerobic fecal batch cultures were used to determine the effects that oligosaccharides derived from orange products had on the composition of the fecal microbiota. The effects were measured through fluorescent in situ hybridization to determine changes in bacterial populations, fermentation end products were analyzed by high-performance liquid chromatography to assess short-chain fatty acid concentrations, and subsequently, a prebiotic index (PI) was determined. Pectic oligosaccharides (POS) were able to increase the bifidobacterial and Eubacterium rectale numbers, albeit resulting in a lower prebiotic index than that from fructo-oligosaccharide metabolism. Orange albedo maintained the growth of most bacterial populations and gave a PI similar to that of soluble starch. Fermentation of POS resulted in an increase in the Eubacterium rectale numbers and concomitantly increased butyrate production. In conclusion, this study has shown that POS can have a beneficial effect on the fecal microflora; however, a classical prebiotic effect was not found. An increase in the Eubacterium rectale population was found, and butyrate levels increased, which is of potential benefit to the host.

Pectic oligosaccharides as prebiotics

Pectic oligosaccharides were observed to have bifidogenic prebiotic properties. Pectic oligosaccharides were also found to possess anti-adhesive properties for food pathogen toxins and they stimulated apoptosis of colon cancer cells. Orange peel albedo (white part) was a good source of pectic oligosaccharides with prebiotic properties. Microwave and autoclave extraction produced pectic oligosaccharides with higher degrees of polymerization than those produced with an ultrafiltration dead-end membrane enzyme reactor. We propose that these larger orange albedo pectic oligosaccharides may have greater persistence through the colon, making them excellent candidates for second generation prebiotic product development.

Polyunsaturated fatty acids of the n-6 and n-3 series: effects on postprandial lipid and apolipoprotein levels in healthy men

OBJECTIVE: The present study was carried out to determine effects of test meals of different fatty acid compositions on postprandial lipoprotein and apolipoprotein metabolism. DESIGN: The study was a randomized, single blind design. SETTING: The study was carried out in the Clinical Investigation Unit of the Royal Surrey County Hospital. SUBJECTS: Twelve male normal subjects with an average age of 22.4 +/- 1.4 years (mean +/- SD) were selected from the student population of the University of Surrey; one subject dropped out of the study because he found the test meal unpalatable. INTERVENTIONS: The subjects were given three evening test meals on three separate occasions, in which the oils used were either a mixed oil (rich in saturated fatty acids and approximated the fatty acid intake of the current UK diet), corn oil (rich in n-6 fatty acids), or fish oil (rich in n-3 fatty acids) 40 g of the oil under investigation were incorporated into a rice-based test meal. Triacylglycerol-rich lipoproteins-triacylglycerol (TRL-TAG), TRL-cholesterol (TRL-cholesterol), plasma-TAG, plasma cholesterol (T-C), and serum apolipoprotein A-I and B (apo A-I and B) responses were measured. Postprandial responses were followed for 11 h. RESULTS: Postprandial plasma-TAG responses, calculated as incremental areas under the response curves (IAUC) were significantly reduced following the fish oil meal [365.5 +/- 145.4 mmol/l x min (mean +/- SD)[ compared with the mixed oil meal (552.0 +/- 141.7 mmol/l x min) (P < 0.05) and there was a strong trend towards the same direction in the TRL-TAG responses. In all instances, plasma-and TRL-TAG showed a biphasic response with increased concentrations occurring at 1h and between 3 and 7h postprandially. TRL-cholesterol, T-C, and serum apo A-I and B responses to the three meals were similar. CONCLUSIONS: The findings support the view that fish oils decrease postprandial lipaemia and this may be an important aspect of their beneficial effects in reducing risk of coronary heart disease (CHD). Further work is required to determine the mechanisms responsible for this effect.

A novel antiserum specific to apolipoprotein B-48: application in the investigation of postprandial lipidaemia in humans

1. Apolipoprotein B-48, the transport protein for chylomicrons, is identical with apolipoprotein B-100 for the first 48% of its sequence. No antiserum has yet been reported that can recognize apolipoprotein B-48, but not apolipoprotein B-100. 2. In the present study an antiserum was raised to the C-terminal sequence of apolipoprotein B-48, using specific chemical reactions to ensure that the charged carboxyl group of the C-terminal isoleucine residue was free. In a Western blot the antiserum was shown to bind to a protein band having the characteristics of apolipoprotein B-48, but not to apolipoprotein B-100. 3. In the early evening 11 subjects were given a test meal which contained 40 g of mixed oil and retinyl palmitate. Blood samples were collected over 9 h. Chylomicron-enriched fractions were prepared and analysed for triacylglycerol, retinyl palmitate and apolipoprotein B-48, the latter after separation using SDS/PAGE and visualization by chemiluminescence on a Western blot. Both triacylglycerol and apolipoprotein B-48 showed an early peak at 1 h, which was not seen with retinyl palmitate. All three substances gave a broader peak between 5 and 6 h postprandially. Retinyl palmitate concentrations declined rapidly during the late (6-9 h) postprandial period, but apolipoprotein B-48 concentrations remained elevated. 4. This study has shown that an antiserum has been produced which is specific for apolipoprotein B-48. This has enabled measurement of postprandial concentrations of the protein that revealed features of chylomicron metabolism which have not been reported previously.