A REVIEW OF TEXTURAL DEFECTS IN COOKED RECONSTITUTED LEGUMES —THE INFLUENCE OF STRUCTURE AND COMPOSITION

Legumes provide an important part of the world's protein requirements, as well as other nutrients, but they are underutilized as food. A major factor limiting expanded consumption is storage induced textural defects that prolong cooking time and demand correspondingly higher energy requirements for preparation. These defects, including the hard-to-cook phenomenon and hardshell, are initiated by structural and compositional factors but can be at least partially controlled by storage and processing conditions. Structural components implicated include seed coat, cell walls, middle lamella, starch granules and membranes while, compositionally, proteins, carbohydrates, phytate, polyphenols and lignin may also be important. Methods of texture measurement of legumes, including mechanical, physical and sensory properties are reviewed. The most commonly held hypothesis for the mechanism of the hard-to-cook defect states that beans fail to soften after exposure to high temperature and humidity storage because the increased water activity potentiates phytase which hydrolyzes phytate, rendering it no longer capable of chelating the Ca⁺⁺ and Mg⁺⁺ ions of the middle lamella and, hence, undissoluble. More recent evidence, however, provides potential roles for lignification, starch gelatinization and perhaps other mechanisms depending upon conditions. The possibility of a nonenzymatic as well as an enzymatic route is raised and thoughts presented on a course of action for future research.     

SOLAR TUNNEL DRYING OF TURMERIC (CURCUMA LONGA LINN. SYN. C. DOMESTICA VAL.) FOR QUALITY IMPROVEMENT

Turmeric is one of the most ancient medicinal spices of the world. As its homeland, India acts as the largest producer, exporter and consumer of turmeric. The value of turmeric is due to its color and flavor, which is being given by curcumin, volatile oil and oleoresin. The end quality of turmeric is very much dependent on its post-harvest methods. Traditionally, open sun drying is the chief method adopted for processing. In the present investigation, freshly harvested turmeric rhizomes were collected from 30 stations and drying experiments were conducted by adopting three methods: (1) solar tunnel drying; (2) conventional drying; and (3) commercial drying. Various pre-drying and post-drying treatments were conducted. The results proved that conventional processing could maintain the intrinsic quality up to a certain level, but extrinsic quality could not be achieved. Solar tunnel drying method is an effective alternative to traditional open sun drying, where retention of curcumin, volatile oil and oleoresin was high, with less drying time. The study also disclosed the importance of pre-drying and post-drying treatments and hygienic practices to be adopted during processing.

PRACTICAL APPLICATIONS

Solar tunnel dryer can be used to process most of the spices, vegetables, fruits and other perishable crops with maximum retention of intrinsic quality and for better shelf life. Substantial reduction of drying time and physical quality improvement with regard to international quality standards are the other advantages.     

The influence of breed on the organoleptic characteristics of Zamorano sheep’s raw milk cheese and its assessment by instrumental analysis

The aim of this study was to investigate the effects of three different somatic cell count (SCC) values on the sensory characteristics of sheep’s milk cheeses from the Castellana and Churra breeds (allowed for Protected Designation of Origin Zamorano cheese manufacture) and the Assaf breed (foreign), determined by typical consumers and instrumentally. The results show that the sensory characteristics of hardness, intensity of taste, and pungency reflect a significant influence of the SCCs of the original milk whereas breed significantly affects colour intensity and hardness (Warner‐Bratzler maximum shear force; WBSF). The instrumental parameters most closely related to the assessments of the typical consumers were WBSF and the value of a*, for hardness and colour respectively.     

Development of Food Ingredients from Navy Beans (Phaseolus vulgaris) by Roasting, Pin Milling, and Air Classification

Eight Navy bean samples, roasted between 92 and 125°C in a particle-to-particle heat exchanger, were ground to produce whole bean and hull flours. Dehulled bean flours were also separated into high protein (HPF) and high-starch fractions (HSF) by air classification. Whole bean flours contained 1.92% fat and 25.8% protein on the average. Hull flours contained between 31.2 and 50.2% dietary fiber, of which approximately 60% was crude fiber. Dehulled bean flour containing 26.8% protein was fractionated into HSF and HPF with average protein contents of 15.6 and 43.1%, respectively. Greater protein shift may be further accomplished by finer grinding and adjustment of the cut point. Residual trypsin inhibitor activity of HPF s ranged from 25–108 TIA/mg protein, down from 116 units in the raw control HPF. Hemagglutinins were inactivated from 110 HA units/mg to values ranging from 2.4–105 HA units/mg.     

Protein Quality of Selected Muscle Foods as Affected by the Exchange of Dietary Wheat Bran for Cellulose

The exchange of 8.4% neutral detergent fiber (NDF) of wheat bran for 8.3% NDF of cellulose in diets containing either beef, chicken, fish or casein as protein sources did not (P>0.05) alter feed consumption, weight gain or energy intake in the protein efficiency ratio (PER) bioassay with weanling rats. Higher (P<0.05) fecal nitrogen (N) excretions and lower (P<0.05) N digestibilities occurred for each protein source when wheat bran was exchanged for cellulose. The exchange also had no effect (P>0.05) on PER or net protein ratio (NPR) of casein or fish protein or on NPR of chicken protein. However, PER and NPR of beef and PER for chicken were reduced (P<0.05) when the dietary fiber was exchanged.     

MODELING THE EFFECT OF MICROSTRUCTURE ON FOOD EXTRACTION

Several cases of extraction of food components were analyzed applying the diffusion theory and Fick's second law to different microstructural architectures. A mathematical algorithm was developed for a two‐dimensional heterogeneous system and programmed in MATLAB. Architectures examined include: (1) structure with straight pores, (2) flake with impermeable platelets, (3) matrix with impermeable dispersed particles and, (4) cellular material. Results show that the architecture of phases in the solid matrix is more important than parameters normally used to correct the diffusivity for structural effects (tortuosity, porosity, volume fraction, etc.). Simulated extraction curves were similar to those obtained from experimental data where an empirical effective diffusivity was calculated. These results suggest a more fundamental approach to modeling of extraction in foodstuffs based on the microstructure and local architecture.