Are the Blueberries We Buy Good Quality? Comparative Study of Berries Purchased from Different Outlets.

Blueberries (Vaccinium corymbosum L.) are becoming increasingly popular for their nutritional and health benefits, and their economic value is therefore increasing. The loss of quality that can occur due to softening and fungal attack is an important consideration when marketing blueberries. Despite the added value of blueberries, no studies have been carried out on how the fruit arrives at the outlets just before purchase by the consumer in terms of firmness, physico-chemical parameters, phenolic compounds, and fungal growth. The aim of this work has been, therefore, to investigate possible differences in quality parameters between blueberries purchased from ten different outlets, regardless of the supplier. The results showed that all the samples were of acceptable quality, although they all had a low maturity index at the point of sale. None of the samples studied showed clear signs of fungal decay at the time of purchase, although we were able to grow and identify some pathogen specimens after cultivation. In terms of total phenolic and anthocyanin content, as well as antioxidant activity, all the samples showed low values, possibly due to their postharvest storage, but they were within the expected range for this fruit. On the other hand, differences in the measured parameters were observed between samples of the same cultivar while no differences were found between conventionally and organically grown blueberries. This suggests that preharvest (such as edaphoclimatic conditions, agricultural practices, and cultivars) and postharvest factors (such as treatments used, storage, and transport temperatures) could influence the berry quality when they reach the consumer.

Physical effects of dietary fibre on simulated luminal flow, studied by in vitro dynamic gastrointestinal digestion and fermentation.

During the transit through the gastrointestinal tract, fibre undergoes physical changes not usually included in in vitro digestion studies even though they influence nutrient diffusion and might play a role in gut microbiota growth. The aim of this study was to evaluate how physical fibre properties influence the physical properties of gastrointestinal fluids using a gastrointestinal model (stomach, small intestine, ascending colon, transverse colon, and descending colon) (simgi®). Analysis by rheological and particle size characterisation, microbiota composition and short-chain fatty acid (SCFA) determination allows the achievement of this goal. First, the water-holding capacity (WHC), microstructure, and viscosity of eight different fibres plus agar were tested. Based on the results, potato fibre, hydroxypropyl methylcellulose (HPMC), psyllium fibres, and agar (as a control) were selected for addition to a medium growth (GNMF) that was used to feed the stomach/small intestine and colon compartments in the simgi®. During gastrointestinal digestion, GNMF was collected at 5, 30 and 55 minutes of processing at the gastric stage and after the intestinal stage. Then, samples of GNMF with faecal slurry were collected at 0, 24 and 48 h of colonic fermentation. Results showed fibre-dependence on apparent viscosity. Although psyllium was partially broken down in the stomach (decrease in particle size), it was the most viscous at the colonic stage, opposite to the potato fibre, but both led to the highest total SFCA and acetic acid production profile. On a microbiological level, the most relevant increase of bacterial growth was observed in the faecal Lactobacillus species, especially for HPMC and potato fibre, that were not digested until reaching the colon. Besides fibre fermentability, viscosity also influenced microbial growth, and it is necessary to characterise these changes to understand fibre functionality.

Cider proteins and foam characteristics: a contribution to their characterization.

A capillary sieving electrophoretic method for protein analysis and molecular weight determination was used to characterize ciders from Asturias, northern Spain. The total protein content (Bradford method) and the foam parameters (Bikerman method) were also analyzed to complete this characterization. The polypeptide profile, based on the molecular weight, together with exploratory and classification techniques, that is, principal component analysis (PCA) or linear discriminant analysis (LDA), allowed ciders to be differentiated on the basis of their foam assessment and the apple juice extraction technology used in the cidermaking process. In addition, the application of correlation analysis, that is, canonical correlations (CCA) or partial least-squares (PLS), revealed that the proteins with higher molecular weight were more relevant with respect to cider foamability. PLS analysis also provided a mathematical equation that is able to predict the stabilization time of foam from the polypeptide profile of the cider, because this is the foam parameter most influenced by these compounds.