In vitro biodegradation of hepatotoxic indospicine in Indigofera spicata and its degradation derivatives by camel foregut and cattle rumen fluids

The known accumulation of the hepatotoxin indospicine in tissues of camels and cattle grazing Indigofera pasture plants is unusual in that free amino acids would normally be expected to be degraded during the fermentation processes in these foregut fermenters. In this study, in vitro experiments were carried out to examine the degradability of indospicine of Indigofera spicata by camel and cattle foregut microbiota. In the first experiment, a 48 h in vitro incubation was carried out using foregut fluid samples that were collected from 15 feral camels and also a fistulated cow. Degradability of indospicine ranged between 97 − 99% with the higher value of 99% for camels. A pooled sample of foregut fluids from three camels that were on a roughage diet was used in a second experiment to examine the time-dependent degradation of indospicine present in the plant materials. Results indicated that camels’ foregut fluids have the ability to biodegrade approximately 99% of the indospicine in I. spicata within 48 h of incubation and produced 2-aminopimelamic acid and 2-aminopimelic acid. The time-dependent degradation analysis showed rapid indospicine degradation (65 nmol/h) during the first 8−18 h of incubation followed by a slower degradation rate (12 nmol/h) between 18 h and 48 h. Indospicine degradation products were also degraded towards the end of the experiment. The results of these in vitro degradation studies suggest that dietary indospicine may undergo extensive degradation in the foregut of the camel resulting in trace levels after 48 hours. The retention time for plant material in the camel foregut varies depending on feed quality, and the results of this study together with the observed accumulation of indospicine in camel tissues suggests that although indospicine can be degraded by foregut fermentation, this degradation is not complete before the passage of the digesta into the intestine

Volatile sulfur compounds in pasteurised and UHT milk during storage

Cooked or sulfurous off-flavour caused by volatile sulfur compounds (VSCs) limits acceptance of ultra-high temperature (UHT) milk in some parts of the world. Therefore, the concentrations of VSCs in UHT milk over 16 weeks of storage were studied and compared with those in pasteurised milk. The major VSCs contributing to the cooked flavour were identified using solid-phase microextraction and gas chromatography with pulsed flame photometric detection. Nine VSCs were detected in commercial indirectly processed UHT skim and whole milk. These were hydrogen sulfide, carbonyl sulfide, methanethiol, dimethyl sulfide, carbon disulfide, dimethyl disulfide, dimethyl sulfoxide, dimethyl sulfone and dimethyl trisulfide. An additional VSC was detected but not identified. The concentrations of hydrogen sulfide, methanthiol, dimethyl sulfide and dimethyl trisulfide were initially higher than their reported threshold values indicating their importance in milk flavour, especially cooked flavour. However, they decreased slowly during storage to levels below their threshold values. This decrease corresponded to a decrease in dissolved oxygen level. Four VSCs, carbon disulfide, dimethyl sulfide, dimethyl sulfoxide and dimethyl disulfide, were detected in pasteurised milk; however, their concentrations were lower than their reported threshold values. This paper puts into perspective the significance of VSCs in the flavour of UHT and pasteurised milk, both initially and during storage, and indicates the period of storage for minimisation of cooked flavour in UHT milk

Polyphenol-cellulose interactions: effects of pH, temperature and salt

Response surface methodology was employed to investigate the effects of common food and digestive tract conditions (pH, temperature, sodium chloride) on the adsorption of polyphenols to cellulose. Major dietary polyphenols selectively bound to cellulose to different extents and exhibited different binding behaviour changes with the environment. Three factors were studied, of which pH (3–7) was found to be the most influential factor, followed by temperature (4–37 °C), while NaCl (0–100 mm) had no significant effect on polyphenol adsorption. Polyphenol adsorption was sensitive to variation in physicochemical parameters: cyanidin-3-glucoside > ferulic acid > (+/−)-catechin. Second-order polynomial equation was a significant and adequate model to express the interaction relationships between polyphenol adsorption and changes in the binding conditions, as the experimental test values agreed with predicted adsorption values under optimised binding conditions. These findings contribute to knowledge on the mechanism of polyphenol–cellulose interactions, important for both food quality and nutritional value

Phenolic contents and antioxidant activities of major Australian red wines throughout the winemaking process

Three Australian red wine types (Shiraz, Cabernet Sauvignon, and Merlot) were analyzed for antioxidant activity and a range of phenolic component contents using various spectral methods. More than half of the total phenolic compounds were tannins, whereas monomeric anthocyanins and flavonols were present in much lesser amounts

Microbial metabolites, but not other phenolics derived from grape seed phenolic extract, are transported through differentiated Caco-2 cell monolayers

Grape seed phenolic extract (GSE) is predicted to have health benefits, even though its bioavailability, including digestibility, permeability and ultimate metabolism, are still poorly understood. In vitro gastric and pancreatic digestion and in vitro ileal and faecal fermentation were combined with Caco-2 cell permeability studies for GSE samples. Qualitatively, there was no change in type/number of GSE compounds following gastric and pancreatic digestion and LC-MS analysis. However, the monomers were significantly (P < 0.05) increased after gastric digestion, along with a significant (P < 0.05) decrease in polymers. In addition, all forms of phenolic compounds decreased following pancreatic digestion. However, none of the original GSE phenolic compounds passed the Caco-2 cell monolayer, since all were recovered in the apical compartment. In contrast, the two intestinal microbiota metabolites with deprotonated molecular weights of [M-H]-165/121 and 193/175, that were found both in the ileal and faecal fermented samples, passed the Caco-2 cell monolayer

The rheological properties of calcium-induced milk gels

The study investigated the calcium-induced gelation of milk during heat treatment. Rheological measurements showed that the addition of 10-20 mM calcium chloride caused thickening or gelation of milk on heating at 70 C. Thickening was observed with 10 mM addition, while gelation was evident with ≥12.5 mM additions, as indicated by an increase in the storage modulus (G′) of the calcium-added milk. The final G′ and breaking stress of milk gels made from ≥12.5 mM added calcium increased with calcium addition. Pre-heat treatment significantly affected the strength of calcium-induced milk gels. Strong milk gels were obtained by the addition of 20 mM calcium chloride to pre-heated milk and holding at 70 C for 60 min followed by cooling to 20 C. The technology of making calcium-induced milk gels can be exploited commercially to make non-fermented dairy gels

Stale flavour volatiles in Australian commercial UHT milk during storage

Methyl ketones, aldehydes and free saturated fatty acids were measured in the headspace of samples of two indirectly processed and two directly processed Australian commercial UHT milks during room temperature storage for 16 weeks. The analytes were isolated using headspace solid phase microextraction and analysed by gas chromatography coupled with flame ionisation detection. All methyl ketones and aldehydes increased during storage, With free saturated fatty acids exhibiting little change. On average, the total methyl ketone and aldehyde concentrations in the indirectly processed UHT milks were higher than those in the directly processed samples. A strong correlation was found between the concentration of methyl ketones and various heat indices (furosine, lactulose and undenatured whey proteins) in the milk samples

ERP assessment of functional status in the temporal lobe: examining spatiotemporal correlates of object recognition

NRC publication: Ye

Application of labelled magnitude satiety scale in a linguistically-diverse population

The labelled magnitude scale (LMS) has been found to provide better discrimination of satiety sensations compared to a visual analogue scale (VAS). The perception of satiety in a linguistically-diverse population may produce differences in the numerical ratios due to language acquisition and diversity. The objective of this study was to investigate whether LMS based on perceived intensities of satiety is an appropriate methodology for a linguistically-diverse population. A total of forty three subjects (28 female, 15 male) were asked to quantify the semantic meaning of 47 English words denoting hunger/fullness at various intensities. Forty four percent of the subjects had English as their first language (EFL sub-group) with the remainder having a first language other than English (EOL sub-group). Words with ambiguous evaluation scores were removed and geometric means (GM) were calculated for each remaining words. Eleven final anchoring words were chosen for the bi-polar linear scale and the scale was constructed by setting the GM to +100 and -100 for each extreme. The types of words removed due to ambiguity differed between the two sub-groups as some words had no equivalent in some of the first languages of the EOL sub-group e.g. ravenous and voracious. The scale constructed was asymmetrical with phrases such as extremely full/hungry and very full/hungry located near to negative/positive ends of the linear scale. Phrases such as moderately full/hungry and slightly full/hungry were located within the central zone of the scale. Quantification of the semantic meaning of hunger/fullness words was not significantly different between sub-groups for the eleven phrases chosen as anchor. We conclude that, provided ambiguous words are avoided, labelled magnitude scales in English can be utilised to assess the perception of perceived satiety in a diverse population differing in their first language. (c) 2008 Elsevier Ltd. All rights reserved

Level of natural hepatotoxin (indospicine) contamination in Australian camel meat

Camel meat production for human consumption and pet food manufacture accounts for a relatively small part of overall red meat production in Australia. Reliable statistical data for the Australian production and consumption of camel meat are not available; however, it is estimated that 300,000 feral camels roam within the desert of central Australia, with an annual usage of more than 3000 camels for human consumption, 2000 for pet food manufacture and a smaller number for live export. Despite a small Australian camel meat production level, the usage of camel meat for pet food has been restricted in recent years due to reports of serious liver disease and death in dogs consuming camel meat. This camel meat was found to contain residues of indospicine, a non-proteinogenic amino acid found in certain Indigofera spp., and associated with mild to severe liver disease in diverse animals after dietary exposure to this hepatotoxin. The extent of indospicine-contaminated Australian camel meat was previously unknown, and this study ascertains the prevalence of such residue in Australian camel meat. In this study, indospicine levels in ex situ (95 samples collected from an abattoir in Queensland) and in situ (197 samples collected from camels after field culling in central Australia) camel meat samples were quantitated using a validated ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The quantitation results showed 46.7% of the in situ- and 20.0% of the ex situ-collected camel meat samples were contaminated by indospicine (more than the limit of detection (LOD) of 0.05 mg\ua0kg fresh weight). The overall indospicine concentration was higher (p < 0.05) in the in situ-collected samples. Indospicine levels detected in the present study are considered to be low; however, a degree of caution must still be exercised, since the tolerable daily intake for indospicine is currently not available for risk estimation