Generation of Soluble Advanced Glycation End Products Receptor (sRAGE)-Binding Ligands during Extensive Heat Treatment of Whey Protein/Lactose Mixtures Is Dependent on Glycation and Aggregation.

Heating of protein- and sugar-containing materials is considered the primary factor affecting the formation of advanced glycation end products (AGEs). This study aimed to investigate the influence of heating conditions, digestion, and aggregation on the binding capacity of AGEs to the soluble AGE receptor (sRAGE). Samples consisting of mixtures of whey protein and lactose were heated at 130 °C. An in vitro infant digestion model was used to study the influence of heat treatment on the digestibility of whey proteins. The amount of sRAGE-binding ligands before and after digestion was measured by an ELISA-based sRAGE-binding assay. Water activity did not significantly affect the extent of digestibility of whey proteins dry heated at pH 5 (ranging from 3.3 ± 0.2 to 3.6 ± 0.1% for gastric digestion and from 53.5 ± 1.5 to 64.7 ± 1.1% for duodenal digestion), but there were differences in cleavage patterns of peptides among the samples heated at different pH values. Formation of sRAGE-binding ligands depended on the formation of aggregates and was limited in the samples heated at pH 5. Moreover, the sRAGE-binding activity of digested sample was changed by protease degradation and correlated with the digestibility of samples. In conclusion, generation of sRAGE-binding ligands during extensive heat treatment of whey protein/lactose mixtures is limited in acidic heating condition and dependent on glycation and aggregation.

Extraction and characterisation of protein fractions from five insect species.

Tenebrio molitor, Zophobas morio, Alphitobius diaperinus, Acheta domesticus and Blaptica dubia were evaluated for their potential as a future protein source. Crude protein content ranged from 19% to 22% (Dumas analysis). Essential amino acid levels in all insect species were comparable with soybean proteins, but lower than for casein. After aqueous extraction, next to a fat fraction, a supernatant, pellet, and residue were obtained, containing 17-23%, 33-39%, 31-47% of total protein, respectively. At 3% (w/v), supernatant fractions did not form stable foams and gels at pH 3, 5, 7, and 10, except for gelation for A. domesticus at pH 7. At 30% w/v, gels at pH 7 and pH 10 were formed, but not at pH 3 and pH 5. In conclusion, the insect species studied have potential to be used in foods due to: (1) absolute protein levels; (2) protein quality; (3) ability to form gels.

Indigenous knowledge of shea processing and quality perception of shea products in Benin.

A survey among 246 people belonging to 14 ethnic groups and living in 5 different parklands in Benin revealed different practices to process shea kernels (namely boiling followed sun drying and smoking) and extract shea butter. A relation between parklands, gathering period, and sun-drying conditions was established. Moisture content and appearance of kernels were the selection criteria for users of shea kernels; color was the main characteristic to buy butter. Constraints to be solved are long processing times, lack of milling equipment and high water requirements. Best practices for smoking, sun drying, and roasting operations need to be established for further improvement.

Incorporation of chlorogenic acids in coffee brew melanoidins.

The incorporation of chlorogenic acids (CGAs) and their subunits quinic and caffeic acids (QA and CA) in coffee brew melanoidins was studied. Fractions with different molecular weights, ionic charges, and ethanol solubilities were isolated from coffee brew. Fractions were saponified, and the released QA and CA were quantified. For all melanoidin fractions, it was found that more QA than CA was released. QA levels correlated with melanoidin levels, indicating that QA is incorporated in melanoidins. The QA level was correlated with increasing ionic charge of the melanoidin populations, suggesting that QA may contribute to the negative charge and consequently is, most likely, not linked via its carboxyl group. The QA level correlated with the phenolic acid group level, as determined by Folin-Ciocalteu, indicating that QA was incorporated to a similar extent as the polyphenolic moiety from CGA. The QA and CA released from brew fractions by enzymes confirmed the incorporation of intact CGAs. Intact CGAs are proposed to be incorporated in melanoidins upon roasting via CA through mainly nonester linkages. This complex can be written as Mel=CA-QA, in which Mel represents the melanoidin backbone, =CA represents CA nonester-linked to the melanoidin backbone, and -QA represents QA ester-linked to CA. Additionally, a total of 12% of QA was identified in coffee brew, whereas only 6% was reported in the literature so far. The relevance of the additional QA on coffee brew stability is discussed.

Evaluation of the simultaneous effects of processing parameters on the iron and zinc solubility of infant sorghum porridge by response surface methodology.

The purpose of this study was to improve the micronutrient quality of indigenous African infant flour using traditional techniques available in the region. Response surface methodology was used to study the effect of duration of soaking, germination, and fermentation on phytate and phenolic compounds (PC), pH, viscosity, and the in vitro solubility (IVS) of iron and zinc in infant sorghum flour. The phytate and the PC concentrations of the flour were significantly modified as a result of the duration of germination and fermentation and their mutual interaction. These modifications were accompanied by a significant increase in % IVS Zn after 24 h of sprouting. Except for the interaction of soaking and fermentation, none of the processing parameters exerted a significant effect on the % IVS Fe. The viscosity of the porridge prepared with the flour decreased significantly with the duration of germination, making it possible to produce a porridge with high energy and nutrient density. The use of germination in combination with fermentation is recommended in the processing of cereals for infant feeding in developing countries.

Genetic and environmental impact on iron, zinc, and phytate in food sorghum grown in Benin.

Seventy-six farmers' varieties of sorghum from Benin were distinguished by amplified fragment length polymorphism (AFLP) and clustered into 45 distinct genotypes. The genotype clusters were evaluated for their Fe, Zn, and phytate concentrations to assess the impact of genetic and environmental effects on the composition of the grains and to identify farmers' varieties with high potential Fe and Zn availability. The Fe concentration of the grains ranged from 30 to 113 mg/kg with an average of 58 mg/kg. The Zn concentration ranged from 11 to 44 mg/kg with an average of 25 mg/kg. The phytate concentration of the grain ranged from 0.4 to 3.5% with a mean of 1.2%. The grain-Fe and grain-Zn did not show consistent linkage to genetic variation, but varied significantly across field locations, suggesting a predominant environmental impact. The phytate concentration of the grains appeared to be environmentally as well as genetically determined. No varieties provide adequate Zn to meet nutritional requirements of sorghum consumers. The most promising varieties for Fe supply were tokogbessenou, mahi swan, biodahu, saï maï, mare dobi, sakarabokuru, and chabicouma, as they showed a [phytate]/[Fe] ratio of <14, which is the critical value above which Fe availability is strongly impaired. These varieties could therefore be recommended for the preparation of food products such as dibou, in which processing methods have only a slight diminishing effect on phytate levels. Further research is needed to test these varieties for the stability of [phytate]/[Fe] molar ratio across various environmental conditions.

Possible mechanisms behind the differential effects of soy protein and casein feedings on colon cancer biomarkers in the rat.

In the present studies, several hypotheses were tested to explain previously reported differential effects of soy and casein on colon cancer biomarkers like cell proliferation, fecal fat, fecal bile acid, alkaline phosphatase, and magnesium excretion in rats. In Study 1, the effect of methionine, a limiting amino acid in soy protein and an amino acid that is thought to have a marked effect on colonic cell proliferation, was tested. It was concluded that methionine up to 1% in the diet had no effect on cell proliferation, using the 3H-thymidine assay. The same study revealed that fecal alkaline phosphatase excretion is a good marker for colonic epithelial damage and fecal magnesium excretion is not. In Study 2, the hypothesis was tested that soy fractions enriched with isoflavones and saponins may increase fat excretion and so influence colonic cell proliferation in rats. It was indeed shown that soy protein isolate and an ethanolic extract from soy protein isolate slightly increased fecal fat excretion (up to 1.7-fold). However, fecal water bile acid and free fatty acid concentrations were decreased after feeding soy protein-based diets compared with casein, and no difference in fecal alkaline phosphatase excretion was observed. In Study 3, the lytic potential of soy saponins and the interaction between saponins and some lytic bile acids were tested in vitro. Data suggest a protective effect from soy saponins by reducing lytic activity of cholic acid. The overall conclusion is that soy protein compared with casein influences several colon cancer risk parameters, indicating a more protective rather than a stimulating effect on colon cancer risk.

Activity and concentration of polyphenolic antioxidants in apple juice. 3. Stability during storage.

Kinetic data are reported describing the stability of various classes of polyphenolic antioxidants in an apple juice enriched in these compounds as a function of storage temperature and oxygen concentration. The most thermally sensitive compounds were the various quercetin glycosides and epicatechin, whereas phloridzin and chlorogenic acid were more stable. The quercetin glycosides showed differences in their stability: quercetin galactoside approximately quercetin rhamnoside > quercetin glucoside/rutinoside > quercetin arabinoside. The effect of the presence of oxygen on the degradation rates was clear for only quercetin and to a lesser extent for epicatechin. Accelerated shelf-life testing of enriched apple juice during 4 days at 80 degrees C showed decreases in the antioxidant activity of 20-40%. The parameters obtained were used to predict the stability at different storage conditions. Calculations showed that polyphenolic antioxidants and antioxidant activity of enriched apple juice will be quite stable at ambient or refrigerated storage conditions up to half a year.

Characterization of pea vicilin. 1. Denoting convicilin as the alpha-subunit of the Pisum vicilin family.

Vicilin, a major globulin protein of pea that has been described as "extremely heterogeneous in terms of its polypeptide composition", was extracted from pea flour under alkaline conditions and subsequently fractionated by salt under acid conditions. This procedure induced the separation of vicilin into two fractions, which, after purification, were called vicilin 1 degrees and vicilin 2 degrees. Vicilin 2 degrees was seen on SDS-PAGE to contain the third globulin protein of pea, convicilin (a band at approximately 70 kDa). Vicilin fractions were thus characterized using gel electrophoresis, differential scanning calorimetry, circular dichroism, and pH-dependent solubility in order to determine whether the convicilin should in fact be considered as a third separate globulin protein of pea. On the basis of the results obtained it was concluded that this distinct polypeptide of the Pisum vicilin gene family should be further denoted as a subunit of the salt extractable protein vicilin. The definition of vicilin heterogeneity should therefore be extended to acknowledge the possible oligomeric inclusion of the 70 kDa polypeptide that is here denoted as the alpha-subunit.