The effect of homogenisation on the stability of pineapple pulp

P>Pineapple pulp was homogenised at different pressures, and its stability investigated by way of flow curves, particle size distribution, morphology, cloudiness and sedimentation. The particle size of the homogenised pulp ranged from 400 to 100 mu m for homogenisation pressures of between 0 and 700 bar. The pineapple pulp showed shear thinning behaviour with increasing flow index (n) after processing at higher pressures. In addition, the pulps with smaller particles showed less serum cloudiness, even though the sedimentation tests showed the highest stability for pulp homogenised between 200 and 300 bar. Above 400 bar, the pulp showed phase separation and higher sedimentation indexes, similar to that observed for the untreated samples, which was attributed to the formation of aggregates because of interparticle attraction.

Seasonal drought stress in the Amazon: Reconciling models and observations

The Amazon Basin is crucial to global circulatory and carbon patterns due to the large areal extent and large flux magnitude. Biogeophysical models have had difficulty reproducing the annual cycle of net ecosystem exchange (NEE) of carbon in some regions of the Amazon, generally simulating uptake during the wet season and efflux during seasonal drought. In reality, the opposite occurs. Observational and modeling studies have identified several mechanisms that explain the observed annual cycle, including: (1) deep soil columns that can store large water amount, (2) the ability of deep roots to access moisture at depth when near-surface soil dries during annual drought, (3) movement of water in the soil via hydraulic redistribution, allowing for more efficient uptake of water during the wet season, and moistening of near-surface soil during the annual drought, and (4) photosynthetic response to elevated light levels as cloudiness decreases during the dry season. We incorporate these mechanisms into the third version of the Simple Biosphere model (SiB3) both singly and collectively, and confront the results with observations. For the forest to maintain function through seasonal drought, there must be sufficient water storage in the soil to sustain transpiration through the dry season in addition to the ability of the roots to access the stored water. We find that individually, none of these mechanisms by themselves produces a simulation of the annual cycle of NEE that matches the observed. When these mechanisms are combined into the model, NEE follows the general trend of the observations, showing efflux during the wet season and uptake during seasonal drought.