Quality of cauliflower as influenced by film wrapping during shipment

 Throughout the season, 'Siria' cauliflower heads from three harvesting periods were film-wrapped and stored for 1 week at 1.5  °C to simulate a maximum period of commercial shipment. After cold storage, the heads were kept for 2.5 days at 20  °C to simulate a retail sale period. Different polymeric films – polyvinyl chloride (PVC) of 14 μm thickness, low-density polyethylene (LDPE) of 11, 15 and 20 μm thicknesses and a special LDPE of 11 μm thickness adapted for microwave ovenuse – were used for wrapping. Soluble solid content, pH, titratable acidity, weight loss, physiological disorders, fungal attacks, visual quality and gas composition within packages were monitored. After the shelf life simulation, among the LDPE films studied, the best results were obtained by using 11 μm LDPE. Gas composition (about 16% O₂ and 2% CO₂ during cold storage, and about 11% O₂ and 3.5% CO₂ during retail sale simulation), overall quality, yellowing and browning of the head, and Alternaria spp. development were at similar levels among the films studied. However, weight loss was considerably lower for all LDPE films than for PVC film. For commercial purposes 11 μm LDPE could be a good alternative to PVC for wrapping cauliflower. Received: 30 October 1998 / Revised version: 18 January 1999     

Fresh-cut broccoli florets shelf-life as affected by packaging film mass transport properties

In this work, the influence of packaging film mass transport properties on the quality loss of fresh-cut broccoli florets is addressed. The work was divided into two subsequent experimental steps; first, the selection of potential packaging films was carried out by monitoring the headspace gas concentrations in package of broccoli. Then, the mass transport properties of some previous selected films were assessed on product shelf-life. To this aim, unpackaged fresh-cut broccoli and intact broccoli wrapped in polyvinyl chloride were used as controls. Headspace gas concentration, mass loss, sensorial quality and spoilage microbial growth were monitored. The micro-perforated films were the most effective in reducing mass loss, wilting and maintaining sensory quality for a longer period. In particular, the micro-perforated film that had the lowest OTR value showed the best performance in prolonging of the product shelf-life if compared to either control samples and fresh-cut broccoli packaged in the non-perforated film. The results highlighted that an approximately 50% shelf-life increase of fresh-cut florets broccoli compared to whole broccoli, and of about 30% respect to the unpackaged fresh-cut produce was obtained.     

Quality of french fried potatoes as influenced by coating with hydrocolloids

Potato french fries were coated with a combination of calcium chloride and either pectin or sodium alginate at different levels. The best treatment was selected for the second coating with different hydrocolloids. Qualities of single- and double-coated french fries were evaluated. Potato french fries coated with sodium alginate as a first coating had less oil reduction and less quality than those coated with pectin. Single-coated french fries with a combination of 0.5% calcium chloride and 5% pectin had the highest reduction of oil content as well as the highest moisture content. Also, coated french fries at these levels exhibited higher red and yellow colours and were firmer than the control. Coated french fries with 0.5% calcium chloride and 5% pectin had higher sensory scores for all attributes compared to the control. French fries coated with carboxy methyl cellulose (CMC) as a second layer were more effective than those coated with pectin or sodium alginate in reducing the oil content. The incorporation of CMC at 1.5% level as a second layer reduced the oil content by 54%; however, the single coating with 0.5% calcium chloride and 5% pectin reduced the oil content by 40%. Double-coated french fries had higher moisture contents and firmer structures than the single coated french fries. Increasing the level of the hydrocolloid forming the second coating up to 1.5% resulted in non-significant differences in the sensory scores for all attributes. Scanning electron microscope photographs indicated that the single- or double-coating process was effective in protecting the cellular structure of potato tissues from the damage produced during deep-fat frying. ©     

Quality attributes of frozen okra as influenced by processing and storage

Sensory evaluation and chemical analyses were carried out on unblanched, steam-blanched (5 min, 100°C) and water-blanched (3 min, 98°C) okra held in frozen storage (–18°C) for 4, 8, 12 and 32 weeks. Hot water-blanched frozen okra compared favourably with fresh samples, even after 32 weeks, in colour, flavour and overall acceptability and was superior to steam-blanched and unblanched except in viscosity. Blanching, especially in steam, improved ascorbic acid retention during frozen storage. Little change in protein occurred.     

Quality of carrot juice as influenced by blanching and sonication treatments

A study was conducted to evaluate the influence of blanching and sonication on important quality parameters of carrot juice. Blanching of carrots was done in normal water and acidified water (45 g/L citric acid, pH 1.3) at 100 °C for 4 min and juice was extracted. Sonication of juice was done (frequency 20 KHz and amplitude level 70%) at 15 °C for 2 min. Significant increase (P < 0.05) was observed in total carotenoids, lycopene and lutein in blanched samples, however, this increase was more in simultaneously blanched and sonicated samples. Additionally, highest increase was observed in all these pigments as a result of combined treatment of acid blanching and sonication. Sucrose, glucose, fructose, chlorogenic acid and mineral elements (Na and K) were decreased significantly in all blanched samples while increased significantly (P < 0.05) in all sonicated samples. Significant decrease was observed in some minerals (P and Mg), total plate count, yeast and mold in all samples treated with blanching and sonication but this decrease was more in samples treated with acid blanching and sonication. The results suggest that combined treatment of blanching and sonication may successfully be employed for processing of carrot juice to improve quality.     

纳米膜和PVC膜包装对西兰花贮藏保鲜的影响

为探究纳米膜和PVC膜对西兰花的保鲜作用,分别采用0.03 mm厚的纳米膜、PVC膜和0.04 mm PE膜(CK)包装西兰花,于常温下贮藏,对其感官、生理指标和营养指标进行测定。结果表明:室温下贮藏,纳米膜和PVC膜包装有效延缓了西兰花外观品质、水分及TSS、V_C、叶绿素等营养物质含量的下降;纳米膜和PVC膜包装可显著抑制西兰花的黄化及MDA积累,增强西兰花POD和CAT活性。这说明纳米膜和PVC膜包装对西兰花的保鲜效果有显著影响,PVC膜包装的西兰花保鲜效果更好。      

Individual wrapping of radishes with food packaging film

When ‘Taibai’ radishes were individually wrapped with food packaging film, they had a reduced weight and firmness loss and a decreased formation of internal sponginess. When stored at 1 °C, wrapped radishes lost 0.01% of their fresh weight per day when compared with the 0.28% weight loss per day for unwrapped radishes. When stored at 5 °C, wrapped radishes lost 0.02–0.03% of their fresh weight per day when compared with the 0.78% weight loss per day of unwrapped radishes. Wrapped radishes stored for 88 days at 5 °C or 165 days at 1 °C maintained their firmness better than unwrapped radishes. Wrapped radishes had significantly less internal sponginess than unwrapped radishes.     

Quality standards of CTC black teas as influenced by sources of potassium fertiliser

The quality aspects of CTC (crush, tear and curl) black teas were examined against different sources of potassium fertiliser. Potassium supplied as muriate of potash (MOP) improved the liquor components such as theaflavin (TF), thearubigin (TR) and TF/TR ratio at higher levels. The same effect was noticed at lower level itself when the source of K was changed to sulfate of potash (SOP). Termination of K application reduced the TF/TR ratio drastically. The entity responsible for strength, body and colour of tea brew, namely highly polymerised substances, attained its optimum proportion at an NK ratio of 1:0.21 using SOP. Generally, there was a good response from SOP‐treated blocks to caffeine. The flavour index was a maximum at a 1:0.42 NK ratio, using SOP. A slight peak and trough were observed in the case of crude fibre content and water extract over control and MOP‐treated blocks. The leaf K content was negatively correlated with CFC content of made tea. An antagonism was observed between leaf K and Mg. Copyright © 2005 Society of Chemical Industry     

Quality of honeys influenced by thermal treatment

Honey producers have been heating honeys at mild temperatures below 100 °C chiefly in order to prevent post-bottling crystallization. In this study, we aimed to determine the effects of thermal treatment on the HMF content of honeydew and floral honey during the isothermal heating process at mild temperatures. Water content, formol number, total acidity, pH value and minerals were also determined in both honey types as their characteristics differ with composition, which is able to affect the rate of HMF formation. Potassium content and pH value were found as the distinguishing properties and both were greater in honeydew honey than in floral honey (p<0.01). Honeydew and floral honey samples were heated at 75, 90 and 100 °C for 15-90 min and analysed for HMF content by HPLC-RP. The Arrhenius model was used to calculate reaction rate constants and activation energies which were found to be different for each of the honey types. Heating at 90 °C for up to 90 min in floral honeys and up to 75 min in honeydew honeys did not cause a significant increase of HMF and not exceed the threshold level of 40 mg kg⁻¹. Our results show that the excessive HMF content might be related to primitive storage conditions rather than overheating.     

差分法预测稳态贮藏条件下嫩茎花椰菜中叶绿素的变化

为预测果蔬贮藏中化学成分的变化,对贮藏中嫩茎花椰菜的叶绿素进行测定.用 Newton 差分法预测叶绿素在贮藏中的损失.选择离待预测点时间间隔点较近时,预测结果较好.向前差分与向后差分均能很好地预测稳态贮藏时品质的变化,基准点分别取邻近预测点前 3.5 d 和后 3.5 d.Newton 向前差分插值和向后差分插值的相对误差分别为 0.38%和 0.20%.基准点离预测点较远时误差较大.     

Quality of beef loin steaks as influenced by animal age, electrical stimulation and ageing

The tenderness of beef M. longissimus dorsi muscles from cattle about 1 8 months (0-2 tooth) and 54 months (8 tooth) old at the time of slaughter was investigated. The influence of electrical stimulation on the mechanical and sensory panel assessments obtained for loin steaks was examined at 24 h post slaughter and also after ageing three weeks. Effective electrical stimulation of the carcasses produced, at 24 h from slaughter, steaks from both age groups which were uniform, acceptable and predictable in tenderness. The colour of loin steaks from the younger animals was lighter than loin steaks from older animals, while the weep in the vacuum packages was less for meat from the older animals than that from the younger ones.     

Quality of base and sparkling wines as influenced by the type of fining agent added pre-fermentation

A comparison of the effect on base wines of pre-fermentative clarification between a fining mixture (potassium caseinate, bentonite and cellulose microcrystalline) and bentonite was carried out. Fining agents were added to two grape juices from different cultivars: Macabeo and Parellada. These varietal wines are used for making sparkling wine within the appellation (certified brand of origin) Cava. Vinification was done in parallel on an industrial scale (100 000 l). The use of the fining mixture in grape juice made the fermentations more complete and gave wines with less browning ability, more foam stability time and a lower content of nitrogenous fraction, polyphenols and some volatile compounds than the wines treated with single bentonite. Sensorial analysis showed that the wines produced with the use of different fining agents had different organoleptic characteristics. In addition, the effect of fining agent added pre-fermentatively was observed on some components of sparkling wines.     

Growth of pathogenic bacteria in sliced vacuum-packed bologna-type sausage as influenced by temperature and gas permeability of packaging film

Studies on sliced vacuum-packed Bologna-type sausage showed that some pathogenic bacteria may develop quickly at refrigeration temperatures. Yersinia enterocolitica grew rapidly even at 5°C, reaching 10⁶ g^?1 within 2 weeks. Other bacteria did not grow at 5°C, Staphylococcus aureus and Bacillus cereus grew at 8°C and Salmonella typhimurium and Salmonella enteritidis but not Clostridium perfringens grew at 12°C. Therefore even at temperatures which may be found in commercial refrigerators, growth of pathogenic bacteria is possible to levels which have been shown to represent a hazard to health. Gas permeability of the packgging film had relatively little effect.     

Focke 350包装机组小包透明纸起皱现象的消除

Ｆｏｃｋｅ 350硬盒包装机组包装的烟包紧凑、方正、美观 ,但其小包透明纸包装侧边封接容易起皱却是许多烟厂较为头痛的包装质量问题。产生原因主要是由设备本身的包装原理和封接烙铁设计有缺陷造成的。笔者从封接烙铁着手 ,提出了改进方案 ,实施后获得了良好的效果。1　原因分析小包透明纸长边封接烙铁由预封接烙铁和最终封接烙铁组成。其中预封接烙铁在透明纸成型转塔 90度转角处 ,对烟包侧面长边进行定位封接 ,其封接质量的好坏将影响最终封接质量。最终封接烙铁在烟包堆放塔处 ,对连续向上推动的烟包进行间断性封接。根据预封接、最终封…     

Properties of protein-based film from round scad (Decapterus maruadsi) muscle as influenced by fish quality

The properties of film prepared from round scad (Decapterus maruadsi) stored in ice for different times were investigated. Degradation of myosin heavy chain (MHC) was more pronounced with the coincidental increase in total volatile base and trimethylamine contents as the storage time increased (P<0.05). Regardless of storage time, no changes in tensile strength (TS) and elongation at break (EAB) of resulting films prepared from unwashed mince were observed (P>0.05). For the films prepared from washed mince, TS decreased, whereas EAB increased when the storage time of fish increased (P<0.05). However, films prepared from washed mince showed the greater mechanical properties with the lower film solubility and protein solubility than did those from mince (P<0.05). Generally, films prepared from fish stored in ice for a longer time became less transparent, darker and more yellowish. The electrophoretic study revealed that similar protein patterns were observed between films, irrespective of storage time of fish and washing. Therefore, the quality of fish did not show the marked impact on the mechanical property of the resulting films, while washing likely affected the film forming ability.     

Glucosinolates in broccoli sprouts (Brassica oleracea var. italica) as conditioned by sulphate supply during germination

Sulphur (S) fertilization is essential for primary and secondary metabolism in cruciferous foods. Deficient, suboptimal, or excessive S affects the growth and biosynthesis of secondary metabolites in adult plants. Nevertheless, there is little information regarding the influence of S fertilization on sprouts and seedlings. An experiment was set up to evaluate the effect of S fertilization, supplied as K(2)SO(4) at 0, 15, 30, and 60 mg/L, on the glucosinolate content of broccoli sprouts during the germination course of 3, 6, 9, and 12 d after sowing. Glucosinolate concentration was strongly influenced by germination, causing a rapid increase during the first 3 d after sowing, and decreasing afterwards. The S supply increased aliphatic and total glucosinolate content at the end of the monitored sprouting period. S-treated sprouts, with S(15), S(30), and S(60) at 9 and 12 d after sowing presented enhanced glucosinolate content. Overall, both germination time and S fertilization were key factors in maximizing the bioactive health-promoting phytochemicals of broccoli. Practical Application: Germination with sulphate is a simple and inexpensive way to obtain sprouts that contain much higher levels of glucosinolates (health promoting compounds), than the corresponding florets from the same seeds.     

Determination of bulk density of Mirabelle plum during hot air drying as influenced by ultrasound-osmotic pretreatment

Prunes are generally produced by drying fresh plums with a stream of hot air. Changes in various quality indicators, such as bulk density of foodstuffs, have substantial impact on the performance of drying processes. Optimization of bulk density is, therefore, a requirement for development and perpetuity of drying technologies. The aim of this study was to investigate the effect of ultrasound-assisted osmotic dehydration pretreatment on bulk density of Mirabelle plum at various operating conditions (sonication time, concentration of osmotic solution and immersion time in the osmotic solution). Results showed that application of ultrasound-assisted osmotic dehydration, compared to control sample, led to a significant (p < 0.05) increase in bulk density from 1.33 to 9.90 %. Experimental data of bulk density variations versus dimensionless moisture content were well fitted to an empirical power model with high R².     

Antioxidant properties of durian fruit as influenced by ripening

The antioxidant properties of durian (Durio zibethinus Murr., cv. Mon Thong) at different stages of ripening were investigated using fluorometry, UV spectroscopy, and HPLC/DAD analyses. Total polyphenols, flavonoids, anthocyanins and flavanols in ripe durian were significantly higher (p < 0.05) than in mature and overripe fruits. Free polyphenols and flavonoids were at lower levels than hydrolyzed ones. Caffeic acid and quercetin were the dominant antioxidant substances in ripe durian. In these fruits, methanol extracts contained a relatively high capacity of 74.9 ± 7.1% inhibition using β-carotene-linoleic acid assay. Ferric-reducing/antioxidant power (FRAP) and cupric-reducing antioxidant capacity (CUPRAC) assays supported this finding. The correlation coefficients between polyphenols and antioxidant capacities of durian samples with all applied assays were about 0.98. In conclusion, the bioactivity of ripe durian was high and the total polyphenols were the main contributors to the overall antioxidant capacity.