猪牛混合脂肪的物化性质和感官特性分析

运用热性质分析、诱导氧化分析和流变分析,对牛脂肪部分替代猪脂肪后复合脂肪的物化性质及加工产品感官性质的变化进行研究。结果表明:替代添加牛脂肪后,猪牛混合脂肪的物化性质和感官性状均发生了不同程度的变化,相对于猪脂肪4.37 h的氧化反应诱导期(induction period,IP),替代10%、20%、30%猪脂肪的猪牛混合脂肪的IP值分别为4.98、5.62、6.22 h;替代10%、20%、30%猪脂肪后猪牛混合脂肪熔融时热流越来越大,晶型转换所需要的能量随着替代量的增加明显增加,总体表现为猪牛混合脂肪熔融时需要的能量变小;同时,相比于单纯的猪脂肪,猪牛混合脂肪的黏性模量和弹性模量均有一定的上升,结果也显示牛脂肪部分替代猪脂肪明显影响到乳化肠的感官品质,总体可接受性受到明显影响(P0.05)。     

Chemical, Physical, and Sensory Properties of a Sweet Potato French-Fry Type Product During Frozen Storage

Chemical, physical, and sensory properties of a sweet potato Frenchfry type product were determined after 0, 3, 6, 9, and 12 months frozen storage. Analyses included measurements of dry matter, sugars, alcohol insoluble solids, carotene, vitamin C, color, texture and sensory panel scores for color, flavor and texture. Few changes were observed except for an appreciable loss (58%) in vitamin C and an apparent increase in carotene (27%). A partial drying treatment before freezing increased the rate of ascorbic acid loss. For the fried product, no appreciable storage-induced changes were noted in the sensory scores for color, flavor and texture thus indicating that the product had good stability in frozen storage.     

Binding, Sensory and Storage Properties of Algin/Calcium Structured Beef Steaks

Structured beef steaks formed with the algin/calcium binder and with or without glucono-delta-lactone were compared with 100% beef controls and with structured steaks formed with salt and phosphate. Algin/calcium-treated products exhibited better binding and color in the raw state, but had lower palatability scores in the cooked state than salt/phosphate controls. Shelf-life of both algin/calcium products under aerobic conditions was similar to the all-beef control. In vacuum packages, however, the algin/calcium products showed more rapid gas production and microbial growth than all-beef and salt/phosphate controls. The algin/calcium treatment will allow increased marketing alternatives for meat products.     

Chemical,Microbial and Sensory Properties of Candied-Pineapple and Cherry Cakes

The chemical, sensory and microbial qualities of candied-pineapple and cherry cakes were investigated. Both cake samples were also analyzed for chemical composition and microbial load before, during and after 56 days storage at room temperature. There were significant differences (p < 0.05) in the physico-chemical composition of the cherry cake and candied pineapple cake except for protein values of 9.00% and 8.63% respectively and magnesium content with values of 0.23% and 0.27% respectively. Sensory evaluation results showed significant differences (p < 0.05) between the two samples with the exception of colour (7.84) for both samples and texture (7.84 and 7.80) for cherry and candied pineapple cakes, respectively. In terms of general acceptability, the candied-pineapple cake was most preferred (8.52). The microbial loads (bacterial and fungal) of the candied pineapple cake were lower than the cherry cake throughout the duration of the 56 days storage at room temperature. The highest bacterial load was recorded after the 28th day (148.0 × 10⁵ cfu/g) and (194.30 × 10⁵ cfu/g) for candied pineapple and cherry cakes respectively. The fungal load was also highest at 28th day of storage (14.33 × 10¹ cfu/g) and (12.67 × 10³ cfu/g) for candied pineapple and cherry cakes respectively. The total viable counts (TVC) were within acceptable limits for human consumption. Therefore, candied-pineapple can readily substitute cherry in fruit cake making in Nigeria.     

不同产地灰枣感官及理化特性评价

以国内六个主产区的灰枣为研究对象,采用模糊感官评价法对不同产区灰枣进行综合感官评价,同时对灰枣质构参数、色差参数和理化营养参数进行了差异性分析。结果表明新疆若羌地区灰枣综合感官评分最高为85.62分,河南新郑灰枣样品综合感官评分最低为72.62分,新疆灰枣总体感官评价高于新郑灰枣;果皮差红色值a值变化范围为21.78～24.63,果肉黄色值b值变化范围为28.44～32.22,其中图木舒克地区灰枣果皮红色度最高,和田地区灰枣果肉黄色度最高;质构数据表明,阿拉尔、若羌地区灰枣果实硬度较大,口感较紧实,耐咀嚼,新郑地区灰枣的咀嚼性和内聚性相对较差;各产地灰枣总糖含量范围为76.47～84.95 g/100 g,还原糖含量范围为32.30～46.90g/100g,总酸含量范围为4.28～5.34g/kg,维生素C含量范围为15.56～30.12mg/100g,总酚含量范围为1622.30～1756.00 mg/kg,新疆地区灰枣各营养指标明显高于河南新郑灰枣;感官与理化相关性表明果皮色差a值可以表征灰枣果实的色泽品质,硬度、咀嚼性等质构参数能够评价灰枣果实的组织状态。     

Double Layer Coatings: A New Technique for Maintaining Physico-Chemical Characteristics and Antioxidant Properties of Dragon Fruit During Storage

A double layer coating was evaluated for maintenance of quality of dragon fruit during storage at 10?±?2 °C and 80?±?5 % RH for 28 days. Significant differences (p?<?0.05) were observed between control and the treated fruit. However, a double layer coating with 600 nm droplet size?+?1.0 % conventional chitosan showed promising results in all the tested parameters, while the fruit treated with 1,000 nm droplet size?+?1.0 % conventional chitosan showed some negative effects on fruit surface. Increase in weight loss was 12.0 % in fruit treated with 600 nm droplet size and 1.0 % conventional chitosan as compared to the control. Antioxidants and gaseous analysis also proved the efficacy of double layer coatings with 600 nm droplet size?+?1.0 % conventional chitosan. Thus it can be concluded from the present investigation that double layer coating could be used for maintaining quality in dragon fruit for up to 28 days without any off-flavours.     

Physico-Chemical Properties,Composition, and Oxidative Stability of Olive and Soybean Oils Under Different Conditions

Commercial olive and soybean oils have been analyzed periodically in order to evaluate the influence of storage conditions on quality. The following parameters were determined every 10 days of storage: peroxide, saponification and acid values, absorption coefficients K₂₇₀ and K₂₃₂, phenols, chlorophylls and carotenoids contents, DPPH scavenging ability, and total antioxidant activity. Edible oils were exposed to daylight and stored at room temperature in different containers with the same surface area of exposure to air either in clear glass or opaque glass bottles. Changes in oils properties were also examined after the addition of Vit-E as an antioxidant in oil samples. The results showed a gradual loss of quality during storage, especially in clear glass bottles. The addition of the antioxidant, however, significantly reduced the deterioration and oxidation rate in the oil. The best containers for commercial packing of oil were opaque glass bottles containing antioxidant products.     

Sensory, Colour and Psychrotrophic Bacterial Analyses of Squids (Loligo plei) During Storage in Ice

The after catch quality decrease of squid, Loligo plei, was evaluated, comparing two storage treatments: contact and non-contact with ice. The squids were evaluated for their sensory, instrumental colour and psychrotrophic bacterial count changes. A principal component analysis of the sensory data indicated that the squid quality markedly decreased after 7 days of storage, in both treatments. The instrumental colour analysis showed that the red and yellow colours of the squid skin increased with time in both treatments, while in the muscle, the intensity of the red and yellow colours increased more in the non-contact than in the contact with ice treatment. The results of the sensory and instrumental colour analyses were highly correlated, both being adequate for squid quality evaluation. The storage methods did not affect the development of bacterial counts, which in both treatments were below 106 cfu/g of muscle after 16 days of storage. The results showed that in both treatments the end of the shelf-life of L. plei squid was determined by the loss of its sensory quality. The packaging of the squids resulted in more intense changes in the characteristic colour of the squid muscle, and did not promote a significant reduction in microbial growth. Thus the non-contact ice storage method presented no advantages when compared with the contact ice storage method with respect to the quality preservation of L. plei under laboratory conditions.     

Sensory Characteristics of Cottage Cheese Whey and Grapefruit Juice Blends and Changes During Processing

Studies were conducted to determine the sensory characteristics of pasteurized blends of cottage cheese whey and grapefruit juice (0%, 25%, 50%, 75% and 100% whey), and the effects of processing alternatives and storage at 3°C. A trained sensory panel rated six attributes (grapefruit, sweetness, sourness, astringency, cheesiness, saltiness). Cheesiness and saltiness increased, while sourness, astringency, sweetness, and grapefruit flavor decreased as the percentage of whey increased. Protein removal did not affect the sensory characteristics, but vacuum stripping reduced cheesiness and increased grapefruit flavor and sweetness. Lactose hydrolysis increased sweetness and decreased cheesiness in blends with more than 50% whey. The flavor of most blends was stable for 14 wk at 3°C.     

Physico-Chemical Properties,Stability, and Potential Food Applications of Shrimp Lipid Extract Encapsulated by Complex Coacervation

Lipid extract from shrimp cephalothorax is a potential food coloring owing to its intense red color. However, it presents some drawbacks, such as its characteristic odor, astaxanthin instability, and difficult dosage and manipulation. The present work is an attempt to overcome these problems by means of complex coacervation encapsulation using gelatin and gum arabic as wall materials. Round molecules in which the lipid extract was efficiently encapsulated in the form of multiple droplets were obtained. The resulting microcapsules stabilized by freeze-drying had good properties with a view to their application as food coloring, owing to their intense red color, improved astaxanthin stability, and low water activity, water solubility, and hygroscopicity. The coloring capacity and sensory properties were evaluated when added to yogurt and a gellified fish product. For yogurt, a trained sensory panel determined that encapsulation effectively reduced the characteristic odor, whereas the coloring capacity was improved, as compared to non-encapsulated lipid extract. For the gellified fish product, no sensory improvement was observed, but the encapsulated lipid extract provided an attractive, uniform color.     

Analysis and Stability of the Sweetener Sucralose in Beverages

The stability of the sweetener sucralose in a range of prototype beverages was confirmed. Storage conditions were chosen to encompass the typical shelf life of the products under investigation plus some extreme conditions. The methods developed for the analysis of the beverages used high performance liquid chromatography with refractive index detection. The reproducibility of each method was determined by means of recovery experiments. Stored samples were also subjected to sensory evaluation. Sucralose was stable under all the conditions tested thus demonstrating the potential suitability of this sweetener in soft drinks.     

Effect of Phosphate Blends on Stability of Cod Fillets in Frozen Storage

Atlantic cod fillets were dipped in commercial tripoly or metaphosphate solutions, frozen and stored at either –12 ° 0.5°C or –30°C (constant or with daily programmed fluctuations to ?26°C) for up to 26 wk. Phosphate treatments at both storage temperatures decreased thaw drip and cooked drip and yielded a product with higher raw and cooked moisture. Protein content of cooked drip from fillets stored at –12°C was reduced by phosphate treatment; no significant difference was found between treated and control samples at –30°C. Although salt extractable protein was lowered, phosphate treatment did not affect dimethylamine/formaldehyde formation. Sensory evaluation of treated fillets stored at –30°C (with daily fluctuation to –26°C) revealed phosphated fillets to be the most tender and, after 26 wk storage, the most highly acceptable. Tripolyphosphate treatment significantly retarded the increase of expressible fluid under abusive conditions of frozen storage.     

Microbial, Enzymatic, and Chemical Changes During Storage of Fresh and Processed Orange Juice

Microbial, enzymatic, and chemical comparisons were made on orange juice stored at 4°C without pasteurization, with light pasteurization (66°C, 10 sec) directed at vegetative microorganisms, and with full pasteurization (90°C, 60 sec) directed at the heat stable isozyme of pectinesterase. Effects of oxygen-barrier and nonbarrier packaging were also examined. Oxygen-barrier packaging did not benefit unpasteurized juice. However, lightly and fully pasteurized juices in barrier cartons exhibited lower microbial counts, greater ascorbic acid retention, and apparent slowing of cloud loss by the third week of storage. During the first 22 days storage, microbial, cloud, sugar, and ascorbic acid values for lightly pasteurized juice were similar to those of juice receiving full pasteurization.     

贮藏过程中冷却牛肉微生物模型的建立

冷却牛肉贮藏过程中易受微生物的污染,通过建立微生物数学模型,可以预测冷却牛肉的污染情况。实验以自然污染下的冷却牛肉为介质,对0、4、7、10、15、20℃恒温条件下的菌落总数进行计数,利用SAS软件拟合Modified Compertz方程,并对比生长率和时间拟合了平方根二级模型,最后在波动温度下对模型进行了验证。结果显示,Modified Compertz方程能很好地反映冷却牛肉中菌落总数的污染情况,恒定温度下的模型拟合度都在0.95以上,对波动温度条件下的菌落总数的预测值与实测值进行比较,偏差度为0.90,准确度为1.12,表明菌落总数生长模型可以可靠地预测冷却牛肉的微生物污染情况。     

Chlorophyll Stability During Continuous Aseptic Processing and Storage

Spinach puree was aseptically processed and packaged at four time-temperature treatments (19.2 and 5.3 sec @ 142°C; 19.2 and 12.2 sec @ 137°C). Samples processed at 142°C for 5.3 sec retained 68% of total chlorophyll compared to blanched samples while all chlorophylls were degraded in retorted product. The rate of chlorophyll b degradation and pheophytin b formation during storage in flexible containers at 4, 25, and 40°C fit a first order kinetic model. Apparent activation energies during storage for each time-temperature treatment ranged between 11.1 and 14.3 kcal/mol. Analyses of degradation products indicated oxidation during storage was not a dominant factor in chlorophyll conversion and color loss.     

Stability of Proteins in Ultrafiltered, Low-Lactose Milk Concentrate During Frozen Storage

Cascin in concentrated milk (3×) destabilizes after 1–3 wk at –8°C. USC of an ultrafiltration (UF) process to partially remove lactose from milk, followed by replacement of all or part of the removed lactose with corn syrup, glucose or sucrose can greatly extend protein stability. Protein stability improves as the amount of nonlactose carbohydrate is increased and the amount of lactose is decreased. Although nutritionally significant amounts of minerals and vitamins arc removed by this process, they can be easily replaced. Samples of skim and whole milk from which 68–72% of the lactose is removed by UI: and replaced on an equal weight basis with corn syrup are stable for more than 34 wk at –8°C.     

Sensory Evaluations and Changes in Peroxidase Activity During Storage of Frozen Green Beans

Total, soluble and bound peroxidase activities were studied on frozen green beans stored under proper conditions (–18°C, -22°C, and in display freezer) and under adverse conditions (with temperature fluctuations). Blanching inactivated the enzyme; there was no regeneration for 12 mo at -22°C, but a slight regeneration at - 18°C. Sensory quality of the properly stored product was acceptable 1 yr or longer. Storage in a display freezer over 60 days did not affect peroxidase activity. Temperature fluctuations were deleterious for sensory quality and total peroxidase activity was only slightly regenerated.     

Sensory and Texture Properties of Mashed Potato Incorporated with Inulin and Olive Oil Blends

The effect of adding different ratios of inulin and extra virgin olive oil blends, formulated without (MPA) and with cryoprotectants (MPB), on texture properties of fresh mashed potatoes and frozen/thawed mashed potatoes was studied. Inulin and extra virgin olive oil behaved like soft fillers, but inulin was associated with increased fibrousness and extra virgin olive oil with increased creaminess. In the total dataset and frozen mashed potatoes, frozen/thawed mashed potatoes, and MPA subgroups, component 1 was a contrast between mechanical and surface textural attributes, whereas in MPB samples component 1 was determined by geometrical attributes. Addition of inulin at 30 g/kg and extra virgin olive oil at 45 g/kg is recommended.