Band 1, Heft 4

Capsicum annuum samples were dried at different air-drying temperatures, ranging from 30 to 90ºC. Modelling of the drying curves was satisfactory when the Page model (average percentage of explained variance was 99.0 ± 0.2%) was used, whereas the Peleg model provided a less accurate simulation (average percentage of explained variance was 91± 14%). Both k and n parameters of the Page’s model exhibited a clear temperature dependence. In fact, n parameter varied linearly with the temperature (r2=0.92), whereas k parameter followed an Arrhenius relationship (r2= 0.96). An activation energy value of ca 27 kJ/mol was estimated using the Page equation. Air-drying temperature influenced the final quality of the dried red pepper (paprika). According to the results, drying within the range of 50 to 75ºC, would be the optimum conditions to achieve a final product with the best colour characteristics (highest ASTA and chroma values) and also, with the highest antioxidant capacity.

The influence of five different emulsifying salts on casein peptization (dissociation) and apparent viscosity of processed Gouda cheese was studied. Casein peptization was evaluated as peptization coefficient in the final product, while apparent viscosity was determined as flow behavior and consistency indices in the product during processing before cooling. Increasing moisture content and pH of processed cheese samples generally increases peptization coefficient, however the type of emulsifying salt showed to play an important role also. On the contrary, independently of the type of emulsifying salt, predictive regression models were suggested in order to express flow behavior index and consistency index versus chemical composition and pH. Increasing moisture content or reducing pH increases the flow behavior index. Consistency index, and thus the apparent viscosity, of processed cheese samples was increased when the moisture content was reduced, and when pH and the soluble casein content were increased.

The effects of high-pressure (33, 400 and 700 MPa for 3 min at 24 and 55°C) and irradiation (2 and 5 kGy) pre-treatments on hydration behavior of navy beans were studied by soaking the treated beans in water (1:2, w/w) at 24 and 55°C. Beans hydrated at 55°C and allowed to cool by natural convection served as the control. Treating beans under moderate pressure (33 MPa) resulted in high initial moisture uptake (0.59 to 1.02 kg/kg dry mass) and reduced loss of soluble materials. The final moisture content after three hours of soaking was the highest in irradiated beans (5 kGy) followed by HPP (33 MPa; 3 min; 55°C). Within the experimental range of the study, Peleg’s model was found to satisfactorily describe the rate of water absorption of navy beans. Peleg's constant K1 had an inverse correlation with soaking temperature whereas K2 increased with increases in temperature and pressure.

There has been recent interest in developing small-scale smoking technologies that respect French sanitary recommendations concerning benzo(a)pyrene deposition on food. The conceptual and embodiment phases of design, and the sizing of a smoker in which this deposition phenomenon is limited are reviewed in this paper. The conceptual phase of design has lead to a process based on the operations of smoking, heating and drying units, using cooled smoke, radiant plates and supplying flows of this cooled smoke directly to the product. For marketing reasons, the power supply is exclusively derived from the combustion of small logs and the smoke comes from sawdust pyrolysis, this smoke being cooled by flowing through a heat exchanger using ice as a cold source. The embodiment phase of design has lead to a versatile system in terms of smoking, heating and drying functionalities. The sizing of this system is based on knowing the drying kinetic of the product in a traditional smoke house (“boucan”); it was performed by estimating heat and mass transfer phenomena occurring between the product and its surroundings. It leads to a kiln having a thermodynamic efficiency close to 13%.

In the developing countries animal proteins are very expensive and cannot meet with the protein requirement of the current explosive population trend hence, supplementing with plant protein is pertinent. Soybean, which is widely consumed when processed to flour and flour products, is one of the best substitutes if properly processed. This study, therefore, aimed at establishing the best thermal treatment among the commonly used methods that will conserve the protein content of soy flour maximally, result in high flour yield and acceptability. Four different methods: Roasting (ROA), Extrusion (EXT), Boil and Sun Dry (BSD) and Boil and Oven Dry (BOD), were used to prepare samples from Tax 1448 soybean variety obtained from International Institute for Tropical Agriculture (IITA) and mixed variety obtained from market. The samples were milled in an attrition mill and the flours obtained were subjected to proximate, sieve and organoleptic evaluations. The results of the experiment, showed a protein content of 40.5, 40.7, 40.1 and 40.3%, flour yields of 32.0, 3.7, 29.7 and 37.9%, and acceptability of 58.0, 61.0, 36.0, and 48.0% and protein content of 33.7, 34.4, 32.7 and 32.7%, flour yields of 17.0, 5.0, 14.1 and 12.3%, and acceptability of 64.0, 68.0, 48.0 and 60.0% for BOD, EXT, ROA and BSD respectively for Tax 1448 and mixed variety. These results indicated that BOD is a better method over others. EXT, though, has the highest acceptability and protein contents, these values (p < 0.05), have no significant difference from those of BOD. EXT however has a very low flour yield. This study has therefore established that BOD is the best of the commonly used domestic methods for producing acceptable soy flour of high protein content and flour yield.

Effects of single and combined Modified Atmosphere Package (MAP) on the preservation of strawberries were studied in this paper. The modified atmosphere package combined with ozone and edible coating films were used for improving the effect of preservation of strawberry. The results show that the optimum gas composition of MAP tests for strawberry was 2.5%O2+16%CO2. The composite membrane of LDPE & PVC was superior to single LDPE and PVC membranes. The storage tests show that MAP could inhibit the respiration and weight loss of strawberries. Furthermore, it also can retard soluble sugars, titrable acidity and anthocyanin decrease. In addition, the dynamic change of gas composition in package was studied.

In the present paper the potential application of colloidal gas aphrons (CGA) to the recovery of antioxidants from wine-making waste extracts is investigated. CGA were generated by stirring a buffered solution (400 ml) of a cationic surfactant(cetyltrimethylammonium bromide, CTAB) at 8000 rpm for 10 minutes. Trials were carried out on standard solutions (2 ml) of gallic acid (GA) 200 mg/l with varying volumes of colloidal gas aphrons (20-60 ml) generated with varying concentrations of CTAB (2 and 4 mM). Influence of pH, solvent (buffered aqueous solution and ethanol), CTAB to GA molar ratio on recovery were studied. Best recovery (63%) was achieved from an aqueous solution of GA and at a CTAB to GA molar ratio of 16. Separation is mainly driven by electrostatic interactions but pH conditions are to be optimised to preserve the GA antioxidant power.