Showing 19 results for Frozen
Javad Daghigh Roohi, Ahmad Ghoroghi, Seyed Hasan Jalili, Mansour Sadrian, Ferydoon Rafipoor, Monireh Faeed,
Volume 1, Issue 1 (3-2013)
Abstract
Uncoated fish burgers were produced in order to expand the variety of products from Silver carp, Hypophthalmichthies molitrix ,and increase the consumption of this fish species. On the other hand in order to compare the effect of ascorbic acid and vacuum packaging on rancidity inhibition and microbial quality, 3 different treatments of fish burger were produced: 1. Burger with common packaging (Control group), 2. Burger with vacuum packaging 3. Burger with 500 ppm ascorbic acid in common packaging. All the treatments were stored in -18 ºC for 6 months after freezing by a spiral freezer in -35 ºC. Chemical, microbiological and sensory evaluations were determined from time 0 and after that monthly until the 6th month. The TVB-N value increased during the storage period but it never passed out of the standard range. The TBA value increased in all treatments but in ascorbic acid treatment it was significantly lower than the other two groups. The pH amounts during storage period decreased in all treatments homogeneously. Microbial counts in all treatments and especially in vacuum packed burgers decreased during the storage period. Organoleptic test demonstrated the preference of burgers treated by ascorbic acid. The shelf life of control group and burgers with vacuum packaging was determined 3 months at least. The shelf life of treated burgers with ascorbic acid was determined about 6 months specially based on the TBA index and sensory evaluation. Vacuum packaging was more effective to protect burgers of chemical and microbial changes compared to common packaging.
Volume 3, Issue 8 (4-2006)
Abstract
Some physico-chemical characteristics of Iranian linseed oil (Linum usitatissimum) such as oil content (44.25%), refractive index (1.47), peroxide (7.21meqO2/Kg Oil), iodine (170.67gI2/100g Oil), acid (3.10mgNaOH/g Oil) and saponification (191.73mgKOH/g Oil) values and fatty acid profile (C16:0, C18:0, C18:1, C18:2, C18:3) were studied. For preservation of ω-3 ingredients, the linseed oil that containing 43.18% of ω-3 fatty acid, were kept in frozen condition (nitrogen atmosphere and -30 º C temperatures) and its peroxide value was determined after 0, 7, 30, 60 and 90 days. Statistical analysis showed significant difference (p<5%) average amount of peroxide value only in first 7 days of storage time and its increase (8.30%) conformed to international standard.
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Volume 4, Issue 4 (3-2016)
Abstract
The fatty acid composition and changes in silver carp fillet after flash frying, frozen storage and deep frying of was studied. For this purpose, fillets with edible coating and uncoated were tested. Fillets after flash frying for 30s, cooling, packaging and cooling were kept in freezer for three months, then deep fried. Flash frying and final deep frying increased the amount of total fat in fillets. The fat content of samples (5.07% at day 0) changed to 9.52 ± 1.97 and 7.54 ± 2.80 % after flash frying and to 9.33 ± 0.70 and 9.39 ± 0.24 % after final deep frying in uncoated and coated samples, respectively. Moisture content decreased after frying and increased after 3 months frozen storage (P<0.05). Twenty six saturated and unsaturated fatty acids were detected in samples. N-3/n-6 ratio was 3.37 in control samples. This ratio was 0.82 and 0.65 for uncoated and coated samples, respectively after flash frying and decreased to 0.66 and 0.28 after final deep frying. Atherogenic index (AI) and thrombosis index (TI) in day 90 after final deep frying in uncoated and coated treatments were 0.60, 0.53 and 0.57 and 0.69, respectively.
Hadis Amiri, Bahareh Shabanpour, Kaveh Rahmanifarah,
Volume 4, Issue 4 (3-2016)
Abstract
The effects of frozen storage (-20°C) of silver carp (Hypophthalmichthys molitrix) for periods of 0 (control), 2, 4 and 6 months on the qualitative properties of surimi powder was investigated. Qualitative characteristics were assessed through analysis of proximate composition, sensory evaluation, color changes, density, oil adsorption capacity, water holding capacity, protein solubility, emulsifying capacity, emulsion stability, foam capacity and stability, gel forming ability, and thiobarbituric acid value. Most of the qualitative indices decreased significantly (p<0.05) in the treatments, including the water holding capacity and the percentage of protein solubility that, respectively, decreased from 13.4ml/g and 7.42% in the control to 10.46 ml/g and 4.82% after 6 months of frozen storage. Besides, the treatments didn’t show foam. The density and thiobarbituric acid increased significantly with time (p<0.05). Based on the analyses as well as sensory assessment, quality of silver carp surimi powder was maintained in -20°C frozen storage up to four months.
Volume 6, Issue 22 (10-2009)
Abstract
According to increasing trend of the consumption of ready to use leafy vegetables, mainly impact of freezing on sensory attributes of the vegetables and necessity of determination of the best conditions for frozen storage of leafy vegetables, this research carried out for determination of the best frozen storage time and temperature of Allium ampeloprasum, Lepidium sativum and Stureia hortensis mixtures.
This study was done at first for storage of ready to use and comminuted leafy vegetables entitled Ghormeh Sabzi mixture in -9, -12 and -18°C as well as 120, 150 and 180 days by explorer method. At second for frying of vegetables of Ghormeh Sabzi and comparison of sensory attributes of freezed vegetables at each month by experimental method. Sensory attributes all treatments containing color, taste and acceptability were evaluated and compared statistically.
The results of freezing temperature in 3 times indicate that color in -18°C is the first rank (P≤0.05). Flavour has the first rank in -18°C in 120 and 150 days but flavour in 180 days in -12°C is the first rank without significant difference with -9°C and -18°C. Furthermore, acceptability in -18°C in 3 times is the first rank. The results of freezing time during 3 temperatures indicate that color, flavour and acceptability are not significantly different.
The research results indicate that sensory attributes of the vegetables during 180 days frozen storage is affected by freezing temperature mainly rather than freezing time.
Volume 8, Issue 34 (12-2011)
Abstract
Amin Oujifard,
Volume 9, Issue 4 (11-2020)
Abstract
The main focus for this study was to compare and evaluate the quality changes and to determine the shelf life of frozen Scomberomorus commerson fillet using quick and slow freezing methods. Scomberomorus commerson fillets were frozen by slow and quick freezing methods and kept in the freezer at -18°C for 180 days. Then proximate analysis, chemical test (Total volatile base nitrogen; TVN, Thiobarbituric acid; TBA), drip loss, fatty acids profile and sensory analysis were assessed. Generally, Ash content, TBA, and TVN, drip loss, SFA values were significantly increased during storage time where as the moisture, protein, fat, PUFA and MUFA were significantly decreased (P<0.05). The ratio of TVN, TBA and drip loss was found to be higher in slowly as against quickly frozen fish. The PUFA (19.71), MUFA (23.40) and ω3 (14.69) of the quick samples was higher than that of the slow samples (16.99, 22.64, 12.34%, respectively). Regarding sensory analysis, both samples were in acceptable condition but the quality of quick samples was better than slow frozen samples. The quick freezing method was generally much more influent on quality parameters than slow freezing method.
Volume 9, Issue 37 (12-2012)
Abstract
Change in chemical deterioration index (peroxide value, PV; thiobarbituric acid index, TBA; free fatty acids, FFA; total volatile basic nitrogen, TVB-N) and sensory properties (texture, general appearance and eye) of kutum (Rutilus frisii kutum) during 6 months frozen storage (-18 º C) was investigated. PV were increased until month 3, then decreased (P<0/05). During storage period the amount of TBA and FFA increased (P<0/05). TVB-N value did not follow a regular pattern but on the whole increased during storage period. None of the chemical quality parameters exceeded the acceptability limits. These results were supported by the results of sensory analyses. Results of this study showed that kutum has acceptable quality during 6 month frozen storage.
Volume 10, Issue 41 (10-2013)
Abstract
In present study, effects of different levels of inulin (0, 1 and 2%) on the physicochemical and sensory properties and probiotic survival in frozen yogurt was investigated. Results showed that inulin at concentration of 1% had no effect on pH but at level 2% had significant effect on pH. Addition of inulin increased overrun and viscosity. The flow behavior of all samples showed their pseudoplastic nature; power law was the best model to predict their flow behavior. In comparison of control sample, frozen yogurts containing inulin had better melting properties and inulin at concentration of 2% increased the time of first dripping, significantly. Total acceptability of samples revealed that frozen yogurt with 2% inulin had the most appealing sensory characteristics. In terms of probiotic survival, the sample with 2% inulin significantly improved the viability of Lactobacillus acidophilus and Bifidobacterium lactis.
Volume 12, Issue 3 (7-2010)
Abstract
Changes in the fatty acid content, during frozen storage at -24°C of Caspian kutum (Rutilus frisii kutum), golden grey mullet (Liza aurata), common carp (Caprinus carpio), pike perch (Sander lucioperca) and common kilka (Clupeonella cultiventris caspia), caught from south Caspian Sea were studied in the present work. Changes in saturated fatty acids (SFAs), monounsaturated fatty acids (MUFAs), polyunsaturated fatty acids (PUFAs), ecosapentaenoic acid plus docosahexaenoic acid/palmitic acid (EPA+DHA/C16), n3 PUFA/n6 PUFA (n3/n6) and polyunsaturated fatty acids/saturated fatty acids (PUFA/SFA) were investigated during a six month period. Results indicated that due to the decrease in unsaturated fatty acids particularly PUFAs (9.25-23.03%), and lower ratios of n3/n6 (2.02-6.06), EPA+DHA/C16 (polyene index; 0.21-0.65) and PUFA/SFA (0.18-0.64) the poststorage nutritional values of these species significantly decrease.
Volume 13, Issue 4 (7-2011)
Abstract
Changes in the fatty acid composition and biochemical indices of mackerel (which has a
substantial lipid content) and shark (which has negligible lipid content) fillets stored at -
18°C for up to six months were measured. Lipid content was measured (6.35% and
1.38%) in mackerel and shark, respectively; however it decreased during frozen storage
in both fish species. In analysis of fatty acids the amount of PUFA, especially -3 ones,
was more predominant in mackerel than shark, nevertheless, fatty acid composition has
changed in both species during frozen storage. The amount of saturated fatty acids in
contrast with unsaturated fatty acids increased due to oxidation of PUFA. The decrease in
PUFA compounds (40.1% and 23.94%) was as follows: -3 (48% and 42.83%), -3/ -6
ratio (41.36% and 50%), PUFA/SFA ratio (56% and 42.23%) and EPA+DHA/C16 ratio
(55.55% and 46.66%) in mackerel and shark, respectively. For both species, tiobarbituric
acid (TBA), peroxide (PV), free fatty acids (FFA) and total volatile base nitrogen (TVB-N)
values were significantly (P< 0.05) increased with storage time. The results showed that,
among these indices, changes in the PV and TBA in mackerel were significantly (P< 0.05)
larger than in shark; but changes of FFA and TVB-N in shark were significantly (P< 0.05)
higher than in mackerel. It means that oxidative and hydrolytic deterioration are
promoter factors of biochemical changes in mackerel and shark, respectively.
Volume 13, Issue 59 (0-0)
Abstract
Necessity of frozen dough products mostly bread is a daily need of most communities due to its energetic role and being the main meal. The freezing of bread dough, despite of its advantages has some disadvantages like gradual decreasing of dough resistance. The purpose of this research is to investigate the effect of Sodium Stearoyel 2-Lactilat emulsifier (SSL) and whey protein concentrate (WPC) for improving quality of dough and frozen dough structure. Therefore, SSL was used at 0, 0.4, 0.8 % and WPC at 0, 3.75, 7.5 % levels using central composite design. At first, the effect of adding these two substances as independent variables on dough rheological properties was investigated by using farinograph .Then dough samples were stored at -18°C for 1 month and the effect of adding the mentioned substances as independent variables on structure of frozen dough was examined by electron microscoy. Farinograph results showed that adding SSL and WPC had significant effect on water absorption of flour and caused significant increase on the dough development time, dough resistance and valorimetric value. These results also revealed significant decrease of dough softening degree (P<0.01). The pictures obtained by electron microscopy showed that adding these two substances improved structure of frozen dough. In this research, %0.5 SSL and %3.8 WPC was selected as the best treatment after optimizing results by response surface methology.
Volume 13, Issue 59 (0-0)
Abstract
Bread is the major food for a lot of peaple in the world and breadmaking is too long and needs skill. Also, Bread is a food product with short shelf life so for eliminating these problems released frozen bakery products. The freezing of bread dough, despite of its advantages has some disadvantages like decreasing of bread volume, expediting staling and destruction of product finl texture. The purpose of this research is to investigate the effect of Sodium Stearoyel 2-Lactilat emulsifier (SSL) and whey protein concentrate (WPC) for improving quality and staling of the bread from frozen dough. Therefore, SSL was used at 0, 0.4, 0.8 % and WPC at 0, 3.75, 7.5 % levels using central composite design. Dough samples were stored at -18°C for 1 month and the effect of adding the mentioned substances on bagguette bread quality properties was investigated. The results of tuxture profile analysis showed significant effect in the level of 1% about the amount of force applied on bread (P<0.01). Also the results indicated significant effect on increasing spesific volume (P<0.01) and overall admission on sensory evaluation of the bread (P<0.05). In this research, %0.5 SSL and %3.8 WPC was selected as the best treatment after optimizing results by response surface methology.
Volume 14, Issue 6 (11-2012)
Abstract
Yoghurt ice cream (YIC) or frozen yoghurt dessert can be regarded as a healthy alternative to plain ice cream. Also use of soy derived products in food formulations can lead to the development of products of improved nutritional and health promoting values. Yoghurt ice cream was prepared using full-fat soy flour to substitute 55% of non fat dry milk content. Product formulation comprised of 12% SNF, 10% fat, 18% sucrose, 0.4% stabilizer-emulsifier and 0.1% vanillin. The effect of incorporating yoghurt at the rate of 5.3%,15.9%, 26.5%, 37.1% and 47.7% of the total ice cream mix on the flow behavior, physico-chemical and sensory properties of Yoghurt Ice Cream was evaluated as compared with control, devoid of any yoghurt. The mixes all showed pseudoplastic flow behavior, with the viscosity increasing from 0.7 to 1.57 pa s when the yoghurt content increased from 0 to 47.7%. Higher contents of yoghurt in the mixes significantly improved the melting rate of the yoghurt ice cream where the minimum melting rate (16%) was obtained for the sample of 47.7% yoghurt content. The highest overrun value of 58% was obtained for the sample containing 15.9% yoghurt. However the specific gravity of the product decreased with increasing yoghurt content with the highest specific gravity of 1.108 being recorded for control. In the light of these findings, it can be concluded that yoghurt ice cream, containing full fat soy flour, can be successfully made by incorporating 25.6% yoghurt in the mix with the end product maintaining its acceptable sensory characteristics.
Volume 14, Issue 63 (6-2016)
Abstract
Application of combined technology can reduce the disadvantages of each other as compare to their individual process. Osmotic process along with hot air drying and freezing were applied on red beet pieces in this investigation. red beet divided to slices as well as cubes pieces before treatment with citric and ascorbic acids in two levels of 0.1 and 0.3 percent. red beet slices were semi dried in cabinet drier for period of 75 minutes and cubes for 115 minutes and then were placed into polyethylene bags for prior to freezing process in freezer with -25◦C. Different physicochemical characteristics such as acidity, water activity, image processing and texture were evaluated after 2 hour and 30 days. Statistical analysis of data with completely randomized design and SPSS software version 20 during one month preservation showed that cubes pieces of red beet in 0.3 percent of acid solution along with osmotic dehydration has the best and comparable texture, color and quality characteristics as compared to the fresh red beet.
Volume 15, Issue 4 (7-2013)
Abstract
To obtain an optimum formulation for stabilizers–emulsifier in ice cream, different combinations of three stabilizers, i.e. basil seed gum, guar gum, and carboxymethyl cellulose, at two concentrations of 0.15 or 0.35% with or without E471 emulsifier were studied using a simplex-centroid mixture design. The regression models for physical properties and texture smoothness of samples were also established. Generally, increasing ratios of basil seed gum in gums mixture increased the apparent viscosity of ice cream mixes and smoothness of texture, but decreased the melting rate. Increasing proportions of guar gum enhanced overrun of samples. Results suggested that the combination of 96.94% basil seed gum and 3.06% guar gum at the concentration of 0.35% with 0.15% emulsifier produced the optimum ice cream. Subsequently, the interaction of the obtained optimum formulation with κ-carrageenan as a secondary stabilizer was studied at two levels of 0.01 and 0.02%. The pH, draw temperature, overrun, hardness, and melting rate were measured through physical methods. Rheological and sensory analyses were also performed. Inclusion of κ-carrageenan in formulations decreased the values of instrumental hardness and improved the smoothness of the samples; while it had no significant effects on other properties such as draw temperature, overrun, sandiness, and foaminess.
Volume 16, Issue 86 (4-2019)
Abstract
In this research, the effect of whey protein concentrate (WPC) in the concentrations of 13, 16 and 19 percent with some of stabilizers including carboxymethyl cellulose (CMC), pectin and chitosan on the physicochemical properties such as acidity, pH, viscosity, overrun and melting resistance, as well as sensory properties such as taste, texture and overall acceptability in frozen yogurt were investigated. The results of statistical analysis showed that the effect of experimental treatments was significant (P<0.01) on all characteristics evaluated. By increasing the concentrations of WPC, increased the acidity and viscosity of the samples containing all three types of stabilizers, but decreased the pH, overrun and melting resistance percentage of frozen yogurt samples. The samples of frozen yogurt that enriched with carboxymethyl cellulose showed higher viscosity value than samples containing pectin and chitosan, but maximum percentage of overrun and melting resistance was observed in samples containing pectin. In evaluating the sensory characteristics, frozen yogurt containing 13% WPC and pectin had the highest score. According to the results of the physicochemical and sensory properties of frozen yogurt samples, the combination of whey protein concentrate with a concentration of 13% and pectin stabilizer was selected as the superior treatment.
Volume 17, Issue 5 (12-2017)
Abstract
Temporary soil improvement techniques are considered among the most important geotechnical topics. Artificial ground freezing is considered to be eco-friendly, economic, safe and applicable for all types of homogeneous, loose and soft soils. By lowering the soil temperature below zero, the pore water of the soil freezes which leads to improved mechanical properties of soil; it increases the shear and compressive strength of soil, without entering any chemicals into the soil environment. In practice, artificial ground freezing consists of two parts; (i) formation of frozen body before construction or test (active step) and (ii) maintenance of the frozen body during the construction and test procedure (passive step). There are two methods for using artificial ground freezing; (i) open method and (ii) closed method. In the open method, liquid nitrogen is used for cooling. With the evaporation of the liquid nitrogen, the soil freezes and the nitrogen gas is released to the atmosphere. In the closed method, a brine is used which is connected to a refrigeration plant. The brine is circulated until the formation of frozen body. The brine used can be ethylene glycol or calcium chloride. One of the difficulties of studying frozen soils is the absence of triaxial compression apparatus for frozen soils in the national and international markets, because it is an unconventional test apparatus. In this research, a triaxial compresion apparatus was developed for testing of frozen soils in the geotechnical laboratory of the University of Tabriz. This apparatus was placed in a cold and insulated room with minimum heat transfer. The temperature of the room was monitored continuously. This triaxial apparatus for frozen soils was developed using a closed system that is connected to a refrigeration plant.
In this study, void ratio, ice saturation and texture of soil were considered as constant parameters and temperature, confining pressure and strain rate were considered as variable parameters. The soil samples were remolded in the laboratory to represent the in situ soil in the line 2, station H of Tabriz Subway. The in situ soil was poorly graded sand and fully saturated. A special type of mold was designed for this research, that was composed of aluminum material with high heat transfer. The mold was insulated from top and bottom and it was rigid in radial direction. A series of unconsolidated undrained triaxial tests were conducted on samples of the frozen soil using the developed triaxial compression apparatus. The results show that, at constant confining pressure and strain rate, decreasing temperature leads to increase in the shear strength and modulus of elasticity of the soil. Decreasing temperature also results in the yield point of frozen soil occurring at higher strains. Also, at constant temperature and strain rate, increasing the confining pressure increases the shear strength and modulus of elasticity of the soil. At constant temperature and confining pressure, increasing the strain rate leads to a moderate increase in the modulus of elasticity and a significant increase in shear strength of frozen sandy soil. Furthermore, the results show that the poorly graded frozen sandy soil samples tested in this research program show softening behavior. All the stress-strain curves show a peak and a residual state.
Volume 17, Issue 101 (5-2020)
Abstract
In this study, stevia and guar were used as alternatives for sucrose and fat in frozen yogurt formulation, respectively. For this purpose, a completely randomized block design with 0-100% replacement levels for stevia and 0, 0.25 and 0.5 % for guar gum was used. To investigate the effect of applied treatments, the physicochemical properties of frozen yogurt including acidity, viscosity, overrun, firmness, first drop time of melting and amount of melting were measured. The results showed that the viscosity decreased by increasing the level of stevia as a replacement for sucrose, while, overrun increased with increasing levels of sucrose substitution with stevia. All levels of stevia and guar replacement resulted in a significant increase in firmness. Also, with increasing the concentration of stevia and guar gum, the first drop time and stability of the sample increased. The results showed that stevia and guar gum are good alternatives to sucrose and fat, respectively, and samples containing 75-100% stevia and 0.5% guar were identified as the optimal treatment.