RHEOLOGICAL AND SENSORY QUALITY OF READY-TO-BAKE CHAPATTI DURING FROZEN STORAGE

The effect of prolonged frozen storage at − 18C, on the textural and sensory properties of ready-to-bake frozen chapatti (R-BFC) was evaluated. The R-BFC samples were prepared from normal- (control) and microwave-treated (18% moisture content for 80 s) wheat grains. Results showed that the extensibility of dough and maximum load for resistance increased gradually in both the samples during frozen storage; however, the increase was lesser in the treated ones. Chapattis prepared from both R-BFC samples exhibited higher hardness, cohesiveness, chewiness and lower springiness values during frozen storage. Microwave-treated R-BFC samples were rated as better retained in color, texture and overall acceptability scores as compared with control, up to 6 months of storage at − 18C. Thiamin and riboflavin contents were monitored during frozen storage and a loss of 12.0–14.5% in thiamin and 4–6% in riboflavin after 6 months of frozen storage was recorded.

PRACTICAL APPLICATIONS

During frozen storage, various physical, rheological and sensory changes occur in the food products, which determine the consumer's acceptability. The results of this study will help to establish quality of the frozen chapattis with respect to texture, color and aroma which will meet the consumer's acceptance. The protocol for the storage of frozen chapattis will help the industry to deliver the product of optimum quality.     

CONVECTIVE DRYING OF PUMPKIN: INFLUENCE OF PRETREATMENT AND DRYING TEMPERATURE

The aim of this research was to study the influence of blanching as a pretreatment on the drying rate, color and rehydration rate of pumpkin slices ( Cucurbita maxima ) dried in a convective dryer at 50, 60 and 70C.
The different pretreatments did not modify drying time. The diffusion coefficient depended on temperature and moisture content, but not on pretreatments. It varied between 1.6 and 2.9  ×  10⁻⁹ m²/s and activation energy was approximately 35.6 kJ/mol. The rehydration rate of the dried sample, which was found to be influenced by drying temperature but not by the pretreatments, reached about 2 kg water/kg dry solid in about 150 s in boiling water. Color parameters " L " and " b " were influenced by drying temperature and pretreatments. Parameter L varied between 36 and 53 and parameter b varied between 20 and 31. Samples dried at 70C without pretreatments presented color parameter values very similar to those of the fresh sample.

PRACTICAL APPLICATIONS

This work evaluates the pretreatment and drying conditions of pumpkin. Five parameters of the optimal product are considered: pretreatment time, drying time, temperature, color and rehydration rate of the product. With these results, drying of pumpkin can be carried out in industrial convective dryers and the dried product may be used in the preparation of soups, premixed foods, snacks, etc.     

APPLICATION OF RESPONSE SURFACE METHODOLOGY FOR THE OSMOTIC DEHYDRATION OF CARROTS

Osmotic dehydrations of carrot cubes in sodium chloride salt solutions at different solution concentrations, temperatures and process durations were analyzed for water loss and solute gain. The osmotically pretreated carrot cubes were further dehydrated in a cabinet dryer at 65C and were then rehydrated in water at ambient temperature for 8–10 h and analyzed for rehydration ratio, color and overall acceptability of the rehydrated product. The process was optimized for maximum water loss, rehydration ratio and overall acceptability of rehydrated product, and for minimum solute gain and shrinkage of rehydrated product by response surface methodology. The optimum conditions of various process parameters were 11% salt concentration, 30C osmotic solution temperature and process duration of 120 min.     

THE INFLUENCE OF MICROWAVES AND SELECTED MANUFACTURING PARAMETERS ON APPLE CHIP QUALITY AND ANTIOXIDANT ACTIVITY

Apple chips belong to the group of low-processed food products and are an interesting alternative to currently popular snacks. The aim of the work was to estimate the influence of chosen technological parameters on quality and antioxidant properties of apple chips. Thickness of apple slices, drying temperature and initial microwave treatment were analyzed.
On the basis of experimental data, it was established that the drying temperature of 90C was optimal for obtaining products with advantageous sensory value. Apples before drying should be cut into slices 3.5 mm thick and immediately soaked in a solution containing saccharose, apple concentrate, citric acid and SO₂. It was shown that microwave pretreatment of apple slices (150–300 W, 5–10 min) shortened the drying time by about 25% and increased the antioxidant potential by about 30%.

PRACTICAL APPLICATIONS

Because of the increasing incidence of civilization diseases, worldwide interest in snack products that are low in calories and healthy is still growing. The optimum parameters of apple chip production (slice thickness and drying temperature) to obtain a product of high antioxidant potential are presented in this study. It is also shown that application of microwave pretreatment enabled us to shorten the process duration and to reduce the production costs while antioxidant activity remained at a relatively high level.     

EFFECTS OF INULIN AND BULKING AGENTS ON SOME PHYSICOCHEMICAL, TEXTURAL AND SENSORY PROPERTIES OF MILK CHOCOLATE

Chocolates are favorite foodstuffs with high sugar contents. Therefore, in the present study, the production of a low-sugar milk chocolate with prebiotic properties is evaluated. Various ratios of inulin (IN), polydextrose (PD) and maltodextrin (MD) along with sucralose (0.04% w/w) were used instead of sugar. Fifteen formulations were examined to determine some physicochemical, mechanical and sensory properties in order to find their optimum ratios. In general, formulations with high ratios of PD and MD were moister and softer than control. The lowest moisture content and highest hardness were observed for the moderate ratios. In addition, MD induced the least desirable sensorial effects, whereas PD and IN pronouncedly improved the overall acceptability. The optimum applicable range for IN, PD and MD were 14–32% and 71–84%, 7–26% and 67–77%, and 0–20% of sugar substitutes, respectively. Our findings on simultaneous fat and sugar reductions also indicated the possibility of fat cut up to 5% in comparison to previous fat content.

PRACTICAL APPLICATIONS

In this paper, we have reported the influences of inulin (IN) as a prebiotic as well as polydextrose (PD) and maltodextrin (MD) as bulking agents on physicochemical, energy content, texture and sensory properties of milk chocolate using simplex lattice mixture design. To the best of our knowledge, this is the first report in this field with very interesting results and practical applicability. Moreover, our findings showed that the use of aforementioned ingredients instead of sugar could lead to production of low-calorie milk chocolate without having the undesirable textural and physiological effects on the product and consumers. Moreover, the simplex lattice mixture design was found a very useful technique for finding optimum ratios of sugar replacers in formulation.     

The thermal stability of Quorn™ pieces

Summary Quorn pieces were heat-treated at 90 °C, 100 °C and at various F values (equivalent time in minutes at a reference temperature of 121.1 °C) for 6.2–24 min and at different pHs (4.5–6.0). The heat-treated Quorn product was assessed for texture using a Voledkevich probe cell, weight change, and the sensory properties of tenderness, juiciness and overall acceptability. The processed and unprocessed Quorn pieces were examined by electron microscopy. Temperature and pH were found to influence sensory tenderness but not instrumental texture. pH also influenced water absorption. However, in general Quorn pieces were found to be stable to heat processing at 90 °C, 100 °C and 120 °C.     

OPTIMIZATION OF MARINE FISH DRYING USING SOLAR TUNNEL DRYER

Studies were conducted to optimize fish-drying process in a Hohenheim-type solar tunnel dryer to produce safe and high quality dried fish products. Five commercially important tropical marine fish species in the Bay of Bengal such as silver jew fish, Bombay duck, big-eye tuna, Chinese pomfret and ribbon fish were used and drying was performed at 45 to 50 and 50 to 55C temperature ranges. Moisture content of the fish samples reached 16% after 36 and 32 h of drying at temperature ranges of 45 to 50 and 50 to 55C, respectively. Products produced at 45 to 50C were found to be excellent on the basis of flavor, color and texture. Their rehydration ability ranged from 65 to 80% with minimum in big-eye tuna and maximum in silver jew fish. Values of total volatile base, peroxide and aerobic plate count of all the final dried products were within the acceptable limit.

PRACTICAL APPLICATIONS

In this experiment, we optimized the drying process in a Hohenheim-type solar tunnel dryer, constructed using locally available materials, for several commercially important marine fish species in the Bay of Bengal over a wide range of temperature, humidity and moisture content. The data obtained in this study are now successfully used for large-scale production of dried fish of high quality, providing better market price for its producers as well as greater acceptability to the consumers. We also developed another low cost solar tunnel dryer using bamboo, hemp, canvas, rope and polythene sheets, which became very popular among small-scale dry fish producers in the coastal areas of Bangladesh.     

Influence of isolated flaxseed mucilage as a non‐starch polysaccharide on noodle quality

Physicochemical, cooking quality and sensory characteristics of noodles enriched by extracted flaxseed mucilage were evaluated. Noodles were prepared with replacement wheat flour with different mucilage concentrations and drying at different temperatures. Generally, physicochemical and noodle quality characteristics improved with adding flaxseed mucilage compared to control sample. The correlation between optimum cooking time with mucilage concentrations and drying temperatures established by nonlinear regression. The obtained data of cooking yield, swelling index, cooking loss and nitrogen loss were analysed using the two‐dimension response surface method. The mucilage concentration of 3% and drying temperature ranging between 68.2 and 70 °C were the best condition to prepare the noodle with high cooking quality compared to the control sample. The received scores from sensory evaluation showed that replacement of wheat flour by flaxseed mucilage improved the texture and overall acceptability of prepared noodle.     

BRNING TIME AND SMOKING INFLUENCE ON ACCEPTABILITY OF IDIAZABAL CHEESE

Brining time and traditional smoking effects on sensory characteristics (appearance, odor, texture, taste and aftertaste) during ripening of Idiazabal cheese were studied in terms of acceptability. The range of brining time (12, 24 and 36 h) considered in this study showed little effect on sensory parameters. In longer brined cheeses, an improvement of rind acceptability was observed especially at the beginning of the ripening period. In young products the texture of the more salted cheese was preferred, in hard cheeses consumers preferred the less salty ones. The traditional smoking process had a greater effect on sensory parameters perceived by consumers than brining time did. It was observed that smoking had a positive influence on acceptability of rind, paste color and eyes. Smoking also increased odor and texture acceptability.     

EFFECT OF OSMOTIC TREATMENT WITH CONCENTRATED SUGAR AND SALT SOLUTIONS ON KINETICS AND COLOR IN VACUUM CONTACT DRYING

ABSTRACT

An experimental study of osmotic dehydration (OD) of selected heat‐sensitive products was carried out in a laboratory‐scale vacuum contact dryer. Cubes of potato and apple were examined as model heat‐sensitive objects. Experiments were conducted at different conduction heat input levels with wall temperatures in the range 35–45C under vacuum and also in pure vacuum without any external heat input. Detailed investigations were carried out of OD on drying performance, product temperature and color of the dried product.

PRACTICAL APPLICATIONS

Osmotic treatment of potato and apple samples using concentrated sugar solution shows better osmotic dehydration as well as drying rate in a vacuum contact drying system. This information may help to select the osmotic agent in any industrial application for faster drying rate in vacuum contact drying specially for food products. Moreover this work shows the analysis to find out the starting point of precipitation of osmotic agent inside the products in terms of drying time, temperature and moisture content. This information will be helpful for critical analysis in osmotic dehydration technique which in turns may help for optimum design.

     

EFFECT OF GLUCOSE SYRUP SOLID, SUCROSE, HYDROGENATED PALM OIL AND SOY-LECITHIN ON SENSORY ACCEPTABILITY OF DURIAN LEATHER

A two-stage optimization of ingredients in durian leather formulations was conducted using Response Surface Methodology (RSM). In stage 1, the independent variables were glucose syrup solids (GSS) and sucrose, and in stage 2, the variables were hydrogenated palm oil (HPO) and soy-lecithin (SL). Based on the responses to sensory acceptability attributes including taste, aroma, texture, appearance and overall acceptability, the most acceptable formulation was a combination of 10% GSS, 5% sucrose, 2.67% HPO and 0.452% SL. Chemical analysis also showed that during processing nutrient composition was relatively unchanged.     

不同干燥方式对苹果蟠桃纸的感官品质和理化特性的影响

为了研究不同干燥方式对苹果蟠桃纸的感官品质和理化特性的影响,本文采用五种干燥方式（烘箱热风干燥、烤箱干燥、微波炉干燥、烤箱-烘箱联合干燥、烤箱-微波炉联合干燥）制备苹果蟠桃纸,考察不同干燥方式制备的苹果蟠桃纸在感官评定、质构、色泽、褐变度、总酚和维生素C含量、抗氧化活性等方面的差异。结果表明,烘箱热风干燥的产品的形态、口感、色泽、风味更能吸引感官评定人员,感官评定分数为最高（86.7）,总酚类含量最高（5.66 mg GAE/g dw）、抗氧化活性较强（DPPH自由基清除率66.00%,FRAP法测定的总还原能力0.32 mmol Trolox/g dw）,但维生素C含量较低（4.56 mg/100 g）、褐变程度较高。微波炉干燥的苹果蟠桃纸维生素C含量最高（9.78 mg/100 g）,但感官评定分数最低为66.7,总酚含量（4.11 mg GAE/g dw）和抗氧化活性最低（DPPH自由基清除率58.00%,FRAP法测定的总还原能力 0.18 mmol Trolox/g dw）。烤箱-烘箱联合干燥和烤箱-微波炉联合干燥的产品则没有突出优势。综上,建议在苹果蟠桃纸生产中不采用微波炉干燥,采用烘箱热风干燥。     

Modeling and minimizing process time of combined convective and vacuum drying of mushrooms and parsley

The aim of this work was to obtain a technological and economic alternative for mushroom and parsley dehydration combining convective and vacuum drying. Depending of product, this combination of technologies allows minimization of total drying time and avoids negative effects on quality of thermo-sensitive products during drying. Experimental drying curves were determined in a cross-flow convective dryer and in a cabinet vacuum dryer at 35, 45 and 55 °C. The most appropriate theoretical models were obtained and applied for combined processes in order to minimize the overall drying time and avoid final product damage. For parsley at the highest temperature (45 °C), reductions of 63% and 16% in drying time were observed with the combined drying process compared to the sole convective and sole vacuum drying, respectively. This reduction in process time was obtained when dryer change was done at the intermediate moisture condition that determines the highest drying rate during the whole combined process of convective and vacuum drying. For mushrooms, convective drying throughout the process, at the highest temperature (55 °C) compatible with product visual quality, minimized drying time.     

Optimization of ingredients and process conditions for the preparation of tandoori roti using response surface methodology

A model capable of predicting the product quality of tandoori roti has been developed using response surface methodology (RSM) and used to determine the optimum processing conditions. The overall sensory score, which is an indicator of blister size, colour, appearance, handfeel, texture, mouthfeel, taste and aroma, was used to assess the product quality in the preparation of tandoori roti. The optimum conditions which were attained for maximum sensory score (31.6) were: water level – 720mL kg⁻¹ flour (the corresponding farinograph consistency – 800 BU at lever position 1:1), salt level – 11g kg⁻¹ flour, mixing time – 3.7 min in a Hobart mixer at 58 r.p.m., baking time – 37 s, and baking temperature – 425°C.     

SINGLE-SCREW EXTRUSION OF PORK AND SOY FLOUR BLEND

This study examined the rheological properties of defatted soy flour and lean pork blend of various moisture contents extruded in a single-screw extruder and the sensory texture property of extruded meat analogs as the first step to develop commercial low-cost meat analogs that not only resemble real meats but have excellent sensory textures. Additional work was also conducted to examine the effect of moisture content of soy flour under the extrusion condition (high temperature and pressure) on the fiber structure and overall texturization of the extrudate as a result of changes in chemical bonds between soy proteins. The mixture of soy meal with ground lean pork showed significant decrease in viscosity as compared with either soy meal or ground meat alone. The best sensory texture was obtained for the pork-soy flour blend with 41. 3% moisture content at screw speed of 180 rpm under the feeding-metering-die temperature setting of 140–170–80C.     

Far-infrared radiation assisted drying of longan fruit

Oversupply of fresh longan (Dimocarpus longan Lour.) from seasonal production in Thailand needs to be preserved in the form of dried product (exported value of over US$70 million in 2009) to prevent it from being damaged by microorganism. Due to well known limitations of hot air (HA) drying, a new technique of using far-infrared radiation (FIR) in combination with hot air and heat pump (HP) dryers for longan is proposed in this study. Longan with initial moisture content of approximately 84–86% w.b. was dried to about 18% w.b. at the drying temperature of 55 °C in the case of combined FIR-heat pump drying and 65 °C in the case of combined FIR-hot air drying with 80% recycled air. In both cases, the electric power supplied to FIR rods was set at 250, 350 and 450 W. The experimental results are presented in terms of the drying kinetics, dried product qualities (color, shrinkage, percentage of rehydration, water activity, texture, and microstructure) and sensory characteristics of the dried product. The results show that FIR in combination with hot air and heat pump drying increases the drying rate of longan by reducing the drying time. FIR also helps to create more porous structure in dried longan, with porosity increasing with the power supplied to the FIR heaters. The formation of porous structure results in a product with lower shrinkage, improved rehydration, lower hardness and lower toughness than samples dried in the absence of FIR. In addition, the FIR dried longan had a stronger red color and appeared darker. Dried longans obtained by HP, HA, combined techniques and the product from the local market, were all rated similarly by a sensory panel for color, shape, flavor and taste. It is worth noting that the overall energy used for FIR-assisted drying processes decreased with the increase in the power supplied to the FIR heaters.     

INFLUENCE OF PLATE TEMPERATURE AND MODE OF REHYDRATION ON TEXTURAL PARAMETERS OF PRECOOKED FREEZE-DRIED BEEF

The effects of various plate temperatures and rehydration procedures in texture of precooked freeze-dried beef, were evaluated. Frozen precooked commercial beef was freeze-dried at 20, 40, 60 and 80C during 24 h. The rehydration procedure involved two main variables: distilled water at room-temperature and at 80C, for 30 min. The texture profile analysis was performed with a TA-XT2 Texture Analyzer (SMS) for freeze-dried rehydrated samples and compared to frozen precooked beef. The results showed that with a same drying period, the 60C plate temperature and rehydrated in distilled water at room-temperature resulted in a better product texture, in regards to texture parameters hardness and chewiness.     

DRYING METHODS AND QUALITY OF SHRIMP DRIED IN A JET-SPOUTED BED DRYER

The objective of this study was to experimentally investigate the effects of various parameters, i.e., size of shrimp, level and pattern of inlet drying air temperature, on the drying kinetics and various quality attributes of dried shrimp viz. shrinkage, rehydration ability, texture and color during drying in a jet‐spouted bed dryer. It was found that the use of a constant inlet air temperature of 100C yielded dried shrimp of the best quality in terms of low percentage of shrinkage, high percentage of rehydration, low maximum shear force and high value of redness compared to shrimp dried using other conditions. A simple mathematical model that enables prediction of the drying behavior of shrimp in a jet‐spouted bed dryer has also been developed.     

Boning and Storage Temperature Effects on the Attributes of Soft Jerky and Frozen Cooked Free-flow Mince

Hot or cold boning and frozen or chilled storage of beef for 1 mo had no effect on sensory panel acceptability of soft beef jerky (easier to chew than traditional jerky) processed using a two step drying method and a frozen cooked free-flow mince (ground beef) made from the beef. For jerky, panel scores for texture and overall acceptability decreased with increased peak force and softness scores increased with increased final yield. Sensory panelists disliked the greyish-brown color of the cooked free-flow mince. The most acceptable free-flow mince was produced by cooking Alogs@ to 73°C, then mincing at –6°C. The degree of freeflowness and the amount of fines tended to increase with decreasing mincing temperature.