The efficiency of ultrasonic-assisted extraction of cyanocobalamin is greater than heat extraction

Cyanocobalamin, like other water-soluble vitamins, is susceptible to degradation due to exposure to heat, UV, oxygen and pH. Built on our previous finding, this study aimed to assess the extraction efficiency of cyanocobalamin from dietary supplements. Particularly, cyanocobalamin extraction in a 100 °C water bath was compared with ultrasonic-assisted extraction, with and without the addition of 1 mg/L sorbitol, xylitol and erythritol. Ground defatted samples of supplement tablets were initially treated for 15 min, centrifuged and filtered before quantitative HPLC analysis. Addition of sorbitol and xylitol significantly minimised the thermal degradation during extraction in a 100 °C water bath, as shown in measured cyanocobalamin (~145 μg/tablet) that was higher than the control (100 μg/tablet, p < 0.05). Despite the addition of sugar alcohols, mean cyanocobalamin in ultrasonic extracted samples (~170 μg/tablet) was not significantly different from those without (p > 0.05). Overall, mean cyanocobalamin in sonicated samples was higher than heat-extracted counterparts, suggesting that extraction in a 100 °C water bath was likely to cause thermal degradation. It was possible that ultrasonic-assisted extraction had no effect on cyanocobalamin stability and would lead to a higher extraction efficiency. Therefore, 15 min extraction in an ultrasonic bath can be suggested to be adequate to release cyanocobalamin before its quantitative determination.

What is the cobalamin status among vegetarians and vegans in Australia?

Water-soluble vitamin B12 (cobalamin) plays a vital role in normal blood function and neurological functioning. Clinical and subclinical B12 deficiency has been notably reported in vegans, vegetarians, the elderly and metformin-treated diabetics. Currently, the prevalence of cobalamin deficiency among vegans and vegetarians in Australia is lacking; data on dietary intake including supplements and nutritional status are also limited. The increasing multiculturalism of Australia has seen an influx of imported foods, of which some may contain considerable vitamin B12. However, values for such foods are not included in the food composition databases. This review highlights the need to update the food composition database with culturally diverse foods containing vitamin B12. Moreover, the need for assessing dietary intakes and status using the most current best evidence and best practice on nutritional indicators (biochemical and functional biomarkers) to estimate the risk of deficiency and/or depletion is discussed.

Sorbitol enhances the physicochemical stability of B12 vitamers

The stability of B₁₂ vitamers is affected by interaction with other water-soluble vitamins, UV light, heat, and pH. This study compared the degradation losses in cyanocobalamin, hydroxocobalamin and methylcobalamin due to the physicochemical exposure before and after the addition of sorbitol. The degradation losses of cyanocobalamin in the presence of increasing concentrations of thiamin and niacin ranged between 6%-13% and added sorbitol significantly prevented the loss of cyanocobalamin (p<0.05). Hydroxocobalamin and methylcobalamin exhibited degradation losses ranging from 24%-26% and 48%-76%, respectively; added sorbitol significantly minimised the loss to 10% and 20%, respectively (p < 0.05). Methylcobalamin was the most susceptible to degradation when co-existing with ascorbic acid, followed by hydroxocobalamin and cyanocobalamin. The presence of ascorbic acid caused the greatest degradation loss in methylcobalamin (70%-76%), which was minimised to 16% with added sorbitol (p < 0.05). Heat exposure (100 °C, 60 minutes) caused a greater loss of cyanocobalamin (38%) than UV exposure (4%). However, degradation losses in hydroxocobalamin and methylcobalamin due to UV and heat exposures were comparable (>30%). At pH 3, methylcobalamin was the most unstable showing 79% degradation loss, which was down to 12% after sorbitol was added (p < 0.05). The losses of cyanocobalamin at pH 3 and pH 9 (~15%) were prevented by adding sorbitol. Addition of sorbitol to hydroxocobalamin at pH 3 and pH 9 reduced the loss by only 6%. The results showed that cyanocobalamin was the most stable, followed by hydroxocobalamin and methylcobalamin. Added sorbitol was sufficient to significantly enhance the stability of cobalamins against degradative agents and conditions.

Ascorbic Acid Effectively Improved Lutein Extraction Yield from Australian Sweet Lupin Flour

Lutein is a xanthophyll, a bioactive phytochemical that presents itself as colourful pigments in plants. Australian sweet lupin flour has been incorporated as a food ingredient in wheat bread and pasta to improve their sensory property and nutritional quality. However, the amount of lutein in lupin flour has not yet been determined. This is the first study to quantify naturally occurring lutein in Australian sweet lupin flour after the extraction efficiency was optimised. Several organic solvents (acetone, isopropyl alcohol, ethyl acetate and hexane), the use of an ultrasonic bath or a probe, the need for saponification and addition of ascorbic acid (served as antioxidant) were tested to compare the extraction yield. HPLC was employed to analyse lutein in flour. Lowest lutein (68 μg/100 g) was determined in the hexane extract. Samples extracted using an ultrasonic bath (126-132 μg/100 g) contained higher lutein than those extracted using a probe (84-109 μg/100 g). Saponified samples showed significantly less lutein (30-64 μg/100 g) than their respective non-saponified ones (122-134 μg/100 g). Without added ascorbic acid, lutein that was extracted into isopropyl alcohol was 143 μg/100 g and was higher than those released into acetone (92 μg/100 g). When ascorbic acid was added, measured lutein in the extracts of isopropyl alcohol (155 μg/100 g) and acetone (138 μg/100 g) increased by 8 and 33%, respectively. Our results suggested that the choice of extraction solvents and addition of ascorbic acid was crucial for quantitative analysis of lutein, so that the lutein content in lupin flour can be accurately reported.

Effect of Germination and Fermentation on Carbohydrate Composition of Australian Sweet Lupin and Soybean Seeds and Flours

This study investigated the effect of germination and fermentation on the composition of carbohydrates in Australian sweet lupin. Specifically, the amount of sugars (sucrose, fructose, and glucose), starch, oligosaccharides (verbascose, stachyose, and raffinose), and dietary fiber were measured in germinated lupin seeds and fermented lupin flour, and compared with those in soy. High performance liquid chromatography coupled with refractive index was employed for quantitation of sugars, starch, and oligosaccharides, and gas chromatography coupled with a flame ionization detector was used for quantitation of simple sugars in total, and soluble, and insoluble dietary fiber. The enzyme activities of α-amylase and α-glucosidase were compared before and after germination or fermentation. The α-amylase activity in germinated lupin increased to  ∼17 nmol/mL/min/0.1 g and in germinated soy∼32; in fermented lupin, the activity increased to ∼52, while in fermented soy it decreased to ∼20. In general, germination or fermentation decreased the oligosaccharide content, and increased the total sugar in samples (p < 0.05). Total oligosaccharides in lupin after uncontrolled germination were reduced by 98% to 6 mg/g, and after controlled germination reduced by 44% to 86 mg/g. Fermentation with yogurt culture lowered the content of total oligosaccharides due to 94% decrease in stachyose. Total oligosaccharides in soy flour prior to fermentation were 180 mg/g and significantly decreased to ∼124 mg/g in fermented soy. Germination did not affect the starch content. There was no significant change in the amounts of total, soluble, and insoluble dietary fiber after germination or fermentation of lupin except for galactose, which was significantly reduced in germinated lupin seeds. Soluble dietary fiber in germinated soy significantly increased. Germination and fermentation are simple and effective techniques to reduce the oligosaccharides while maintaining the composition of dietary fibers.

The Potential Use of Fermented Chickpea and Faba Bean Flour as Food Ingredients

Apart from being a rich and inexpensive protein source, legumes provide essential vitamins, minerals and dietary fibre. Considering the nutritional benefits, legumes flour can potentially be incorporated in the development of new products. The aim of this study was to investigate whether fermentation affects the protein content, in vitro protein digestibility, trypsin inhibitor activity and the functionality of proteins in faba bean, desi and kabuli chickpea. Australian grown chickpea and faba bean were selected and initially soaked, de-hulled, dried and milled into flour. This was fermented with lyophilised yoghurt cultures in a 30 °C orbital shaker for 16 h. While protein contents in fermented desi and kabuli flour were lower than their raw counterparts (p > 0.05), it was significantly higher in fermented faba bean. A significant increase (9.5%) in in vitro protein digestibility was found in fermented desi. Trypsin inhibitor activity in fermented desi, kabuli and faba bean reduced by 2.7, 1.1 and 4.7%, respectively (p > 0.05). Overall, the in vitro protein digestibility in flour samples increased, while simultaneously reducing the trypsin inhibitor activity. The water absorption capacity of the fermented kabuli flour significantly increased by 11.3%. All fermented flour samples had significantly higher oil absorption capacity than their corresponding raw flour that was likely due to increased insoluble hydrophobic protein. Although, the foaming capacity in all fermented flour samples was significantly lower than their respective raw samples, only fermented desi and faba bean flour showed lower foaming stability (p > 0.05). The present study suggests that fermented legume flour could fulfill the demand for innovative products of higher nutritional value.

Voluntary fortification of breakfast cereals with folic acid: contribution to dietary intake in Australia

Ready-to-eat breakfast cereals have been voluntarily fortified with folic acid since 1995, with the purpose of reducing the prevalence of neural tube defects in utero. Using data from the recent Australian Health Survey, this study aimed to estimate folate intake from one serving of breakfast cereals (median amount). Various commercial brands were purchased in 2002 (n = 19) and in 2014 (n = 14); folate was determined by microbiological assay and high-pressure liquid chromatography (HPLC). Total folate (μg/100 g) in 2002 and 2014 selections were 144-633 and 147-564, respectively, and mostly comparable to nutrition labels. Folic acid (2014 selection) using HPLC, ranged from 85 to 411 μg/100 g. Intake of 51 g cereals/serving by individuals ≥ 2 years could contribute 75-288 μg dietary folate equivalent. It seems that folic acid intake among children (2-3 years) exceeds the recommended dietary intake, when certain brands of breakfast cereals are consumed. Accordingly, the benefits and potential detrimental effects of the voluntary fortification need to be further explored.

Folate analysis in foods by UPLC-MS/MS: development and validation of a novel, high throughput quantitative assay; folate levels determined in Australian fortified breads

An ultra-performance liquid chromatography-tandem mass spectrometry method was developed, optimised and validated for the quantification of synthetic folic acid (FA), also called pteroyl-L: -glutamic acid or vitamin B9 and naturally occurring 5-methyltetrahydrofolate (5-MTHF) found in folate-fortified breads. Optimised sample preparation prior to analysis involved addition of (13)C(5) labelled internal standards, treatments with α-amylase and rat serum, solid-phase extraction using aromatic-selective cartridges and ultra-filtration. Analytes were separated on a Waters ACQUITY HSS T3 column during a 6-min run and analysed by positive ion electrospray selected reaction monitoring MS/MS. Standard calibration curves for the two analytes were linear over the range of 0.018-14 μg FA/g of fresh bread (r(2) = 0.997) and 9.3-900 ng 5-MTHF/g of fresh bread (r(2) = 0.999). The absolute recoveries were 90% and 76% for FA and 5-MTHF, respectively. Intra-day coefficients of variation were 3% for FA and 18% for 5-MTHF. The limit of detection was 9.0 ng/g for FA and 4.3 ng/g for 5-MTHF, determined using pre-extracted tapioca starch as the blank matrix. The assay is rugged, fast, accurate and sensitive, applicable to a variety of food matrices and is capable of the detection and quantification of the naturally occurring low levels of 5-MTHF in wheat breads. The findings of this study revealed that the FA range in Australian fortified breads was 79-110 μg/100 g of fresh bread and suggest that the flour may not have the mandated FA fortification level (200-300 μg/100 g of flour), though this cannot be determined conclusively from experimental bread data alone, as variable baking losses have been documented by other authors.