Effect of seed coat microstructure and lipid composition on the hydration behavior and kinetics of two red bean (Phaseolus vulgaris L.) varieties.

Bean hydration is a crucial, yet complex process affected both by inherent bean properties (intrinsic) and properties of the soak medium (extrinsic) whose relationship with hydration kinetics are not clear. This work investigated the effect of temperature (30-80°C) on the hydration behavior and kinetics of two commonly consumed Phaseolus vulgaris L. beans-red kidney and small red beans. Both beans have similar morphology (except size), chemical composition and seed coat surface structure but, surprisingly, their hydration behaviors differed markedly. Small red hydration followed a sigmoidal shape (to 70°C) with a prominent lag phase at 30-40°C, while fast hydrating red kidney beans followed a downward concave shape, suggesting different mechanisms of water uptake. The hydration behaviors for red kidney and small red beans were modeled using Peleg (R2 ≥0.97) and sigmoidal (R2 ≥0.99) models, respectively. Water uptake rate increased, while equilibrium moisture content decreased for both bean varieties with increasing temperature. A simplified model was developed for small red beans which can predict hydration as a function of temperature and time with good accuracy ( M mod = M expt . × 1.06 - 0.56 ${M_{{\rm{mod}}}} = {M_{{\rm{expt}}{\rm{.}}}}\ \times 1.06 - 0.56$ , R2  = 0.99, RMSE = 4.5). Microscopic examination of cross sections of seed coats showed nearly double parenchyma layer thickness in small red bean and seed coat lipid analysis showed significantly higher proportion of saturated fatty acids which, together, may be responsible for slower water uptake observed in small red beans. PRACTICAL APPLICATION: Hydration is the crucial stage in dry bean processing, which precedes other processes like cooking, extraction, fermentation, sprouting, and consumption. Industrial bean processing is still slow and batch process and needs improvement. This work shows the effect of various bean properties and soaking medium temperature on the hydration behavior of two commonly consumed red beans. The work also modeled the hydration kinetics of two Phaseolus vulgaris L. beans which can be adopted by bean processors for process design and optimization.

An alternative process for cleaning knives used on meat slaughter floors.

Traditionally on slaughter floors operator knives are cleaned by rinsing in hand wash water at 20-40 degrees C followed by brief immersion in baths termed "sterilisers" which contain water no cooler than 82 degrees C. Under Australian legislation, both domestic and export, it is possible for a meat processing establishment to apply to the Controlling Authority for permission to implement an alternative procedure providing that it is at least the equivalent of that legislated. No firm evidence appears to exist for the 82 degrees C requirement and the possibility of replacing this element of the knife cleaning procedure with an alternative procedure using 60 degrees C water and a longer immersion time was investigated at an abattoir slaughtering cattle and sheep. Knives were tested at a range of work stations located along beef and mutton slaughter floors for Aerobic Plate Counts (APCs) and E. coli. For knives used on the beef chain the mean log APC/cm(2) was 2.18 by the current knife cleaning process and 1.78 by the alternate procedure (P<0.001). Using the current system E. coli was isolated from cleaned knives on 20/230 (8.7%) occasions compared with 21/230 (9.1%) occasions using the alternative system. The mean log E. coli of positive knives was 0.43/cm(2) and 0.61/cm(2) from the current and alternative systems, respectively. On the mutton chain the mean log APC/cm(2) was 1.95 using the current knife cleaning process and 1.69 by the alternative procedure (P=0.014). Using the current system E. coli was isolated from cleaned knives on 24/130 (18.5%) occasions compared with 29/130 (22.3%) occasions using the alternative system. The mean log E. coli of positive knives was 0.90/cm(2) and 0.76/cm(2) from the current and alternative systems, respectively. It is concluded that using two knives alternatively, rinsing them in hand wash water, then immersing them between uses in 60 degrees C water provides a microbiological outcome equivalent to rinsing them and momentary dipping in 82 degrees C water.