S. M. Mousavi

Effect of carrier type and spray drying on the physicochemical properties of powdered and reconstituted pomegranate juice (Punica Granatum L.)

Pomegranate juice was diluted to 12° Brix and carriers (maltodextrin, gum Arabic, waxy starch) were added with varying concentrations of cellulose before being reduced to powder by spray drying. All carrier concentrations improved dryer yield, with gum Arabic being the most effective. The bulk density of the powder decreased when higher carrier concentrations were used. As cellulose concentration increased in solution, the solubility of the final product decreased. The optical properties of the powder were affected by the type and concentration of the carrier; powders produced with gum Arabic showed the greatest color change. Adding a carrier increased the Tg of the powder and its storage stability. Variation in the anthocyanin may be related to the type of carrier agent and its behavior during spray drying.

An Investigation of the Effects of Drying Methods and Conditions on Drying Characteristics and Quality Attributes of Agricultural Products during Hot Air and Hot Air/Microwave-Assisted Dehydration

Hot air and microwave-assisted hot air drying of apples (Golden delicious), strawberries (Fragaria vesca cv. Elsanta), tomatoes (Lycopersicon esculentom var. Roma), and mushrooms (A. bisporus) were performed in a commercial microwave oven that had been modified to incorporate a hot air dryer. The same microwave power intensity was used in all experiments. We investigated the effect of the above-stated methods on the structural, optical, mechanical, and rehydration characteristics of dried samples. Scanning electron microscopy (SEM) was used to evaluate the structural damage associated with two drying methods. The drying rate was significantly affected by microwave energy; therefore, drying time was reduced by 80, 70, 74, and 66%, respectively for apples, strawberries, tomatoes, and mushrooms, respectively. Specific volume, particle density, and porosity variation were estimated using models proposed in the literature. Some structural damage occurred, as observed in SEM micrographs. Optical, mechanical, and rehydration parameters were enhanced by microwave treatment for apples, strawberries, and tomatoes. However, negative effects were observed in the case of mushrooms.

Effects of combined coating and microwave assisted hot-air drying on the texture, microstructure and rehydration characteristics of apple slices

The effect of coating, hot-air and microwave drying on the texture, microstructure and rehydration characteristics of Golden Deliciousapple slices (22mm diameter, 4mm thickness) was investigated. Blanching was carried out in hot water (80°C, 1 min) to prevent undesirable enzymatic reactions. To induce a porous structure during microwave treatment, coating with a starch (suspension), pectin and carboxymethylcellulose (CMC) solution (20 g/L) with and without CaCl2 (10 g/L) was carried out. A puncture test and a scanning electron microscopy (SEM) technique were used to analyse the effects of these processes on texture and microstructure. Rehydration in distilled water was also studied. Coating, air-drying (70°C, 1.5 m/s) and microwave treatment (300W, 10s) resulted in the production of puffed and porous products. Microstructure of samples coated by starch and pectin with CaCl2 improved. Coating had a beneficial effect on the microstructure of samples after microwave treatment. In addition, microstructural studies showed that coating with pectin had a significant effect on the thickness of the cell wall whereas those treated with starch or CMC did not exhibit such an effect. Adding CaCl2 to the coating solution improved the microstructural properties and prevented central heating phenomena.

A comparison between sugar consumption and ethanol production in wort by immobilized Saccharomyces Cerevisiae, Saccharomyces Ludwigii and Saccharomyces Rouxii on Brewer's Spent Grain

The immobilization of Saccharomyces cerevisiae DSM 70424, Saccharomyces ludwigii DSM 3447 and Saccharomyces rouxii DSM 2531 on brewers spent grain and then ethanol production and sugar consumption of these immobilized yeasts were investigated. The aim of this study was to investigate the abilities of these three immobilized yeasts for producing alcohol for brewing at two temperatures (7 and 12 °C) using two different sugar levels (one at original level supplied in the brewery and one with 2.5% (w/v), added glucose to the wort). Increasing both parameters resulted in higher alcohol production by all the yeasts studied. At 7 °C and with original wort density the ethanol content at the end of fermentation was 2.7% (v/v) for S. cerevisiae, 1.7% for S. ludwigii and 2.0% for S. rouxii. After the addition of 2.5% (w/v) glucose at the same temperature (7 °C), the alcohol production was increased to 4.1, 2.8 and 4.1%, respectively. Similar improvements were observed when the fermentation was carried out at 12 °C with/without the addition of glucose to the wort. However, temperature indicated greater influence on S. ludwigii than did on S. rouxii and S. cerevisiae. The immobilization as carried out in this study impacted both S. ludwigii and S. rouxii in a way that they could consume maltose under certain conditions.

Chemical composition and evaluation of antimicrobial properties of Rosmarinus officinalis L. essential oil

Preservatives used in the food industry are undergoing increasing scrutiny and reappraisal. There is therefore a renewed interest in the antimicrobial properties of herbs and spices. Rosemary ( Rosmarinus officinalis L.) belonging to the Lamiaceae family, is a pleasant-smelling perennial herb. The antimicrobial activities of the R. officinalis oil against Leuconostoc mesenteroides (PTCC1591), Lactobacillus delbruekii (PTCC1333), Saccharomyces cerevisia (PTCC5269) and Candida krusei (PTCC 5295) were determined. The results indicate that among the tested microbes, the essential oil had a stronger inhibitory effect on the bacteria as compared to yeasts. Minimum inhibitory concentration (MIC) values for bacteria L. mesenteroides , L. delbruekii , S. cerevisia and C. krusei ranged between 0.5 and 1.5 mg/ml. The oil was analyzed by GC and GC/MS. The major components of R. officinalis oil were 1,8-cineole (23.14%), camphor (12.35%), α-pinene (9.87%), β-pinene (6.10%), borneol (5.61%), camphene (5.58%) and α-terpineol (4.30%), respectively. These results indicate the latent potency of essential oil of R. officinalis as a natural preservative in food products against L. mesenteroides , L. delbruekii , S. cerevisia and C.krusei .