YIELD AND QUALITY OF ONION FLAVOR OIL OBTAINED BY SUPERCRITICAL FLUID EXTRACTION AND OTHER METHODS

Methods of extraction of onion flavor oil were studied including supercritical fluid extraction using carbon dioxide (CO₂), liquid CO₂ extraction and steam distillation-solvent extraction. The effect of using entrainers with supercritical fluid extraction was also studied. The yield and the quality of onion extracts obtained from the different methods were compared. The maximum yield of 0.0324% was obtained by supercritical CO₂ extraction at 3600psi (24.5 MPa), 37C at a CO₂ flow rate of 0.5 L/min. Ethyl alcohol used as entrainer enhanced the yield of onion oil over that obtained by supercritical CO₂ experiment without entrainer at the CO2flow rate of 1.0 L/min. Gas chromatography and combined gas chromatography-mass spectrometry of the extracts indicated that the flavor profiles were different for extracts obtained by different methods. Supercritical and liquid CO₂ extracts had fresh onion-like flavor as opposed to a cooked flavor of the extract obtained by steam distillation-solvent extraction.     

Investigation of sorption isotherms of wheat germ for its effect on lipid oxidation

This research aimed to investigate the oxidation and sorption isotherm properties of wheat germ and to determine monolayer moisture content (m₀) in particular, because it has a limiting effect on lipid oxidation. This research comprised two stages. The first stage was the determination of sorption properties and m₀ at three temperatures (15, 25, and 35°C). The second stage of the research was to investigate lipid oxidation properties of stored wheat germ at two different temperatures (4 and 25°C) and m₀ for 28 days. As a result, it was determined that wheat germ has a Type II sorption isotherm, Halsey is the best fitting sorption equation, and the average m₀ is 4.25 g moisture per 100 g dry matter. Furthermore, the free fatty acid and peroxide value of wheat germ oil increased with increasing storage moisture content and temperature, determined as 12.63% and 5.01 mEqO₂/kg on average, respectively. In conclusion, storage of impermeably packaged wheat germ at low temperature and m₀ content is an applicable method for decreasing rancidity and prolonging shelf-life.     

EFFECTS OF NISIN AND MODIFIED ATMOSPHERE PACKAGING (MAP) ON THE QUALITY OF EMULSION‐TYPE SAUSAGE

ABSTRACT

The aim of this work was to study the effects of nisin (30 ppm) and modified atmosphere packaging (MAP) on the chemical, microbial and sensory properties of emulsion‐type sausage stored under two different atmospheres (%CO₂/%N₂/%CO/%O₂): 39.5/60/0.5/0 and 39.5/20/0.5/40. The samples were stored at 3 ± 1C for 42 days. Microbial count, values of pH, CIE L*, a* and b* color parameters, lipid oxidation, production of nitrosomyoglobin and sensory properties were assessed throughout the storage period. The data showed that nisin was able to reduce the growth of mesophilic, psychrotrophic and lactic acid bacteria. In addition, the MAP did not show any significant effects on microbial growth. However, free O₂ MAP, in combination with nisin, reduced the growth of yeast and mold. MAP could produce a stabilized red color and minimize the oxidative reactions in the samples. Packaging conditions had no significant effect on pH and sensory properties.

PRACTICAL APPLICATIONS

The results of this study confirmed that nisin can reduce the growth rate of lactic acid bacteria, psychrotrophic and mesophilic bacteria in emulsion‐type sausage, and free O₂ MAP, in combination with nisin, inhibits the growth of yeast and mold. The use of 30 ppm nisin, in combination with MAP containing 39.5% CO₂ and 0.5% CO gases, can lead to better quality preservation of the emulsion‐type sausages stored at low temperature and can extend their shelf life.     

PREDICTING SENSORY COHESIVENESS, HARDNESS AND SPRINGINESS OF SOLID FOODS FROM INSTRUMENTAL MEASUREMENTS

ABSTRACT

The sensory evaluation of cohesiveness, hardness and springiness of 15 solid food samples was performed by eight trained assessors. The rheologic response of the 15 samples was estimated by performing cyclic compression tests and stress–relaxation tests. From the force–deformation curves of the first two cycles of the compression test, texture profile analysis parameters related to cohesiveness, hardness and springiness were calculated. Young's modulus (E), strain (d_i) and stress (s_i) at peak as well as irrecoverable strain (r_i) and irrecoverable work (L_i) were monitored during the first five cycles. From the stress–relaxation response, Peleg's linearization model parameters, K₁ and K₂, were estimated by best‐fit regression. These parameters were used for predicting sensory attributes. Hardness and springiness were both accurately predicted by rheologic properties, while cohesiveness prediction was less representative.

PRACTICAL APPLICATIONS

This study contributes to enhance the knowledge in the research area of sensory instrumental correlation. Also, the research allows to better understanding that no single instrument is able to measure all texture attributes adequately. In fact, the results demonstrate that both stress–relaxation and cyclic compression tests need to be performed for the correct prediction of sensory responses.     

Effects of rosemary and green tea extracts on frozen surimi gels fortified with omega‐3 fatty acids

Two different sources of omega‐3 fatty acids (fish oil concentrate and menhaden oil) with or without the addition of natural antioxidants (rosemary and green tea) were incorporated into surimi gels at equivalent levels and examined for changes in sensory and physical properties and resistance to oxidation during 9 months of frozen storage. Gels with menhaden oil showed higher acceptance than gels with fish oil concentrate, which displayed a fishy taste that was partially masked by natural antioxidants. Formation of volatile compounds was similar in all samples. Upon heating to form the gel, there was a ca 20–25% decrease in the relative polyene index of the control containing no rosemary or green tea extract. Formulations with menhaden oil containing green tea and rosemary were more stable immediately after cooking; however, a slight pro‐oxidant effect occurred during storage. Omega‐3 fortified gels were whiter than gels with no added oil. Rosemary and green tea extracts increased yellowness (b*) and redness (a*), respectively. Strength increased in all formulations during frozen storage. Copyright © 2005 Society of Chemical Industry     

香辛料提取物对低温油炸肉丝软罐头的抗氧化效应研究

目的通过添加具有抗氧化活性和较高安全性的香辛料提取物,解决中式肉类菜肴的软罐头食品中变色、风味变差以及脂肪氧化酸败等问题。方法向低温油炸肉丝软罐头中添加不同添加量的迷迭香、肉桂和VE提取物以及2种人工合成抗氧化剂丁基羟基茴香醚(butyl hydroxy anisd,BHA)和没食子酸丙酯(propylgallate,PG),测定其对软罐头菜肴产品在贮藏过程中硫代巴比妥酸值(thiobarbituric acid-reacitive substances,TBARS值)、过氧化物值(peroxide value,POV值)和色差值的影响。结果添加的3种共9组天然抗氧化剂中,迷迭香提取物抑制初级氧化产物氢过氧化物和次级氧化产物丙二醛的效果最好(P0.05)。添加300 mg/kg迷迭香、90 mg/kg PG和120 mg/kg BHA的3组处理组在21 d冷藏期内,其POV值和TBARS值显著小于其他各组(P0.05),说明添加300 mg/kg迷迭香可以替代人工抗氧化剂。结论低温油炸肉丝软罐头中添加300 mg/kg迷迭香提取物,可以减缓脂肪氧化速度,进而延长产品的货架期。     

The capability of rosemary extract in preventing oxidation of fish lipid

The effects of rosemary extract at different levels (%1, R1, and %2, R2) on the quality of vacuum‐packed sardine in terms of sensory, biochemical (thiobarbituric acid, total volatile basic nitrogen, peroxide value and free fatty acids) and microbiological analyses (total viable counts) were investigated. Fish were filleted and divided into three groups. First group was used as the control (C) without rosemary extract, second group was treated with 1% rosemary extracts (10 g L^?1) for 2 min (R1), and the third was treated with 2% rosemary extracts (20 g L^?1) for 2 min (R2). Thirty fillets per litre were used. After that, all groups were vacuum‐packed in polyethylene bags. The samples were stored in the refrigerator condition (4 ± 1 °C) over the storage period of 20 days. The results showed that the use of rosemary extract improved the sensory quality of both raw and cooked sardine, most preferably sardine treated with 1% of rosemary. Biochemical analysis showed that the use of 2% of rosemary extract were found to be most effective (P < 0.05) in controlling the rate of lipid oxidation.     

Use of a spouted bed to improve the storage stability of wheat germ followed in paper and polyethlyene packages

Stabilization of wheat germ by heating in a spouted bed for 180–540 s with air at 140–200 °C was studied. The lipase activity decreased by 6–65%. Wheat germ processed at 200 °C for 360 s was ranked highest in sensory evaluation, described as having ‘a golden color’ and ‘nutty flavor’, and its lipoxygenase activity had decreased by 91.2%. This product and raw wheat germ were stored in paper, polyethylene and vacuum‐packed polyethylene pouches at 5 °C, room temperature (18–26 °C) and 40 °C, and the moisture contents, water activities, free fatty acid contents and peroxide values were followed for 20 weeks. The increases were faster in paper pouches than in the polyethylene ones; vacuum packaging in polyethylene did not bring about significant improvement. The peroxide values of raw samples exceeded 10 meq O₂ kg^?1 oil after 3–23 days while those of the processed samples stored at room temperature or 5 °C were still less than 10 after 20 weeks. The free fatty acid content and peroxide value changes were expressed by zero order kinetics, resulting in similar activation energies for the raw and processed samples. Copyright © 2005 Society of Chemical Industry     

Addition of different rosemary preparations (Rosmarinus officinalis L.) to chicken meatballs improves their quality profile

Effect of rosemary (Rosmarinus officinalis L.) preparations in baked, vacuum-packed meatballs from chicken meat during 14 days of storage at +4 °C was assessed. The meatballs were divided into the following groups: RD−with 1.0% of dried spice, REE40 and REE70−with 2.0% of ethanol extracts: 40% (v/v) and 70% (v/v), respectively, and REO−with 0.1% of essential oil. The CONTROL product did not contain added rosemary. In chicken meatballs, the antioxidant stability was determined, microbiological analyses as well as sensory evaluation were performed. After 14 days of storage, the strongest antioxidant activity in the chicken meatballs exhibited rosemary ethanol extracts. Compared with the CONTROL, the REE70 and REO had the best microbiological quality at the end of the storage period. All products with rosemary were sensory acceptable; however, the highest scores in the evaluation of all sensory attributes were obtained by the RD treatment.     

Antioxidant properties of commercial soft and hard winter wheats (Triticum aestivum L.) and their milling fractions

The total phenolic content (TPC), total antioxidant activity (TAA), 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) scavenging capacity, inhibition of coupled oxidation in a β‐carotene–linoleate model system, iron(II) chelation activity and inhibition of copper‐induced oxidation of human low‐density lipoprotein (hLDL) cholesterol of 80% ethanolic extracts of soft and hard winter wheat samples and their milling fractions, namely flour, germ, bran and shorts, were investigated. Soft wheat extracts examined demonstrated higher TPC and TAA compared to those of hard wheat extracts. The germ fraction possessed the highest TPC, followed by bran, shorts, whole grain and flour for both wheat types examined. The TAA of both wheat types showed similar results except that shorts performed better than bran in this assay. Free radical scavenging properties of whole grain and milling fractions of both soft and hard wheat samples were examined against DPPH radical. The germ and flour fractions demonstrated the highest and lowest DPPH radical scavenging activity, respectively, among wheat fractions. Wheat extracts were also efficient in preventing bleaching of β‐carotene, which is also known to be free radical mediated. In the iron(II) chelation assay the flour extracts demonstrated excellent activity, while the germ extracts showed a weak activity. The trends were similar in both soft and hard wheat for the iron(II) chelation assay. Wheat extracts also inhibited copper‐induced oxidation of hLDL. In LDL oxidation assay, wheat extracts performed better than the reference antioxidant, ferulic acid. Thus wheat phenolics may serve as effective antioxidative components as measured by in vitro techniques. Copyright © 2005 Society of Chemical Industry     

COMPARISON OF PEROXIDASES FROM BARLEY KERNEL (Hordeum vulgare L.) AND WHEAT GERM (Triticum aestivum L.): ISOLATION AND PRELIMINARY CHARACTERIZATION

Peroxidases (POD) of crude extracts from barley and wheat germ were separated, partially purified using salt fractionation, ion-exchange and hydrophobic interaction chromatographies and their properties examined. Barley and wheat germ POD contained basic, neutral and anionic isoforms as confirmed by isoelectric focusing. Toyopearl-Butyl 650 M chromatography resolved POD into four cationic fractions. Chromatography of wheat germ extract on CM-Sepharose isolated an anionic and a neutral fraction. Following chromatography on Concanavalin-A Sepharose, enzymes from both cereals showed differences in their elution properties. Optimum pH ranges were 4.0 to 5.5 (barley) and 5.3 to > 6.3 (wheat germ) and POD reacted differently under acidic or basic conditions. Their catalytic behavior in the presence of calcium also differed. Kinetics of POD were of Michaelian type with a ping-pong mechanism and Michaelis constants of guaiacol oxidation in the presence of hydrogen peroxide varied from one enzymatic group to another.     

Inhibition of oxidative rancidity in frozen cooked fish flakes by tert-butylhydroquinone and rosemary extract

The antioxidant properties of tert-butylhydroquinone (0·5 g kg^?1 + 20 g kg^?1 ascorbic acid—TBHQ-AS) and an extract of rosemary (2·5 g kg^?1) alone and in combination were determined by their addition as solutions to cooked fish flakes stored at - 20°C. Oxidation was measured by following changes in free fatty acids, thiobarbituric acid number, fatty acid composition and sensory evaluation. The order of effectiveness in inhibiting oxidation was TBHQ-AS > combination > rosemary > untreated control ?70°C > untreated control -20°C. Sensory evaluation indicated that green aroma and flavor notes were associated with the rosemary extract, while fish oil notes were associated with untreated samples.     

香辛料提取物对速冻牛肉丸脂肪氧化控制的研究

研究添加迷迭香、丁香、肉桂提取物对－18℃冻藏牛肉丸脂肪氧化、颜色稳定性和感官评定的影响。测定结果以肉丸在储存期间的硫代巴比妥酸值(TBARS值)、过氧化物值(PV值)、颜色(L*、a*值)和感官评定指标。结果表明：与对照组相比,随着贮藏时间的增加,添加香辛料提取物的各处理组能够显著延缓脂肪氧化(P＜0.05);亮度L*值呈现出先下降后上升的趋势,而红度a*值逐渐降低;贮藏120d后,添加香辛料提取物的各处理组具有较好的滋气味与颜色。表明添加香辛料提取物在一定程度上可以减缓脂肪氧化速度,同时还可以改善风味,掩盖脂肪氧化酸败味。     

QUALITY AND STORAGE STABILITY OF CHICKEN MEAT PATTIES INCORPORATED WITH LINSEED OIL

ABSTRACT

Low‐fat (<10% total fat) chicken meat patties (CMP) with different levels of linseed oil (LO) i.e., 0, 2, 3 and 4% (control, T₁, T₂ and T₃) were evaluated for their nutritive, processing, textural and storage qualities. The cooking yield, fat and moisture retention were comparable in control and LO‐treated products. The dimensional parameters were better maintained for T₂ among the LO treatments_. The sensory panelists rated T₂ as the best among treatments with comparable sensory attributes to control patties. The selected 3% level of LO was compared with the control for color, texture and fatty acid profile. The lightness (L*) and redness (a*) values were significantly (P < 0.05) less, whereas yellowness (b*) was significantly (P < 0.05) higher for the developed CMP than the control. The chewiness value was higher in control, whereas firmness and springiness were comparable in both the products. The total saturated fatty acid (SFA) content was significantly (P < 0.05) decreased, whereas α‐linolenic acid increased significantly (P < 0.05) in the developed CMP. The ratio of polyunsaturated fatty acids (PUFAs) and SFAs was increased, whereas n‐6/n‐3 decreased in developed CMP. CMP with 3% LO remained physicochemically and microbiologically stable with some deterioration in sensory attributes during aerobic refrigerated (4 ± 1C) storage of 25 days.

PRACTICAL APPLICATIONS

LO is a rich source of omega‐3 fatty acid and is used in the feed of the meat animals for nutritionally better quality meat, which requires long period of rearing and is costly. However, the direct incorporation of LO in the processed meat products poses various technological problems. Therefore, the efficacy of LO as a partial substitute of vegetable oil in the low‐fat omega‐3‐enriched meat products was assessed. The developed processing technology can be commercially exploited for the development of functional/health‐oriented meat products with low fat and low energy, rich in omega‐3 fatty acid, and balanced in PUFA and SFA ratio.

     

Effects of Carbon Dioxide and Ozone Treatments on the Volatile Composition and Sensory Quality of Dry-Cured Ham

Abstract: Randomized complete block designs with 3 replications were utilized to evaluate the effects of carbon dioxide (CO₂) (0% at 96 h, 60% at 48 h, and 60% at 96 h) and ozone (O₃) (0 and 175 ppm for 48 h) on the volatile flavor compound concentrations in dry-cured ham. Minimal differences existed in the presence and concentration of aroma active compounds in both CO₂ and O₃ fumigated hams but phenols were slightly more prevalent (P < 0.05) in the CO₂ treatments and oxidation compounds were slightly elevated (P < 0.05) in the ozone treated samples when compared to the control. Triangle tests (n = 54 and 56) indicated that consumers could not discern (P > 0.75) between the control hams and the hams that were fumigated with CO₂ and O₃, respectively. This study revealed that there were minimal aroma/flavor differences among the ham treatments between 0 and 60% CO₂ for 96 h; and also between 0 and 175 ppm O₃.     

CONCENTRATION OF ONION JUICE VOLATILES BY REVERSE OSMOSIS AND ITS EFFECTS ON SUPERCRITICAL CO2 EXTRACTION

Supercritical carbon dioxide extraction of onion oil at moderate temperatures produces aproduct which is characteristic of the fresh flavor of onions. It was attempted to improve extraction efficiency by concentrating the onion juice by reverse osmosis prior to supercritical CO₂ extraction. Reverse osmosis was carried out for all combinations of 600, 700, and 800 psi feed pressure and 25 and 35C. The juice was concentrated to 18 ^oBtix and then subjected to supercritical CO₂ extraction. The effect of concentration on the extraction process was evaluated by comparing the yields of extracts from concentrated juice with that of single strength juice. Concentration of onion juice by reverse osmosis improved the efficiency of supercritical CO₂ extraction of onion oil and did not alter its characteristic fresh aroma.     

EFFECT OF ROSEMARY ON THE QUALITY CHARACTERISTICS OF WHITE SHRIMP (LITOPENAEUS VANNAMEI)

ABSTRACT

We assessed the influence of rosemary on some of the quality characteristics of Litopenaeus vannamei shrimp stored under freezing temperature for 180 days. Whole shrimp (WS), peeled shrimp (PS) and PS with dehydrated rosemary (RS) were stored at −28.3 ± 3.8C. Physicochemical and sensorial analysis was carried out. After 180 days, RS had lower pH (P = 0.001) and thiobarbituric acid‐reactive substances (TBARS; P = 0.001) values and higher carotenoids (P = 0.003). WS samples were firmer at 180 days (P = 0.001), although rancid taste and smell were perceived with greater intensity (P = 0.001). The color was more intense in RS and PS than in WS (P = 0.030). Rancid taste was detected in RS only at 120 days at significantly lower intensity (P = 0.001) than WS and PS. Our study suggests that dehydrated rosemary can improve the quality of frozen L. vannamei peeled shrimp.

PRACTICAL APPLICATIONS

Farmed shrimp has gained importance in the global market, and the study of their physicochemical and sensory characteristics is therefore essential. Commercially, shrimp is mainly available in the frozen form, and alternatives to extend its quality during storage are of great interest for consumers and suppliers in the food industry. Dehydrated rosemary can be added to frozen shrimp to improve its quality and maintain the nutritional characteristics during storage.