CHARACTERIZATION OF SURFACE AUXIN RESIDUE IN GREENHOUSE TOMATOES (LYCOPERSICON ESCULENTUM)

Greenhouse tomato samples (n = 20) was analyzed before and after peel removal in order to determine surface auxin residue. Mean 4‐CPA residue levels of greenhouse tomatoes with and without peels were 0.383 ± 0.123 mg kg^?1 and 0.241 ±0.085 mg kg^?1, respectively. This difference (36 ±13%) was statistically significant. The frequency distribution curve of tomatoes with peel had a peak point at 4‐CPA reside interval of 0.4‐ < 0.5 mg kg^?1 tomato, and shifted back to 4‐CPA residue interval of 0.2‐ < 0.3 mg kg^?1 for tomatoes without peel. Percentage of samples having 4‐CPA level lower than the critical concentration of 0.5 mg kg^?1 was 80% before peel removal, but increased to 100% upon being peeled. The mean 4‐CPA residue of peels was roughly estimated to be 3.449 mg kg^?1 peel based on peeled versus nonpeeled fruit residue.     

INFLUENCE OF CONVENTIONAL CLARIFICATION AND ULTRAFILTRATION ON THE PHENOLIC COMPOSITION OF GOLDEN DELICIOUS APPLE JUICE

Abstract The effects of conventional clarification and ultrafiltration techniques on the phenolic composition of apple juice was studied. Since the health benefit of fruits and fruit juices have been ascribed, in part, to the phenolic antioxidants, it is very important to know what the effects of processing steps are on the level of phenolic compounds in fruit juices. The total losses of phenolic compounds were determined to be 28% and 7% during conventional clarification using gelatin and bentonite, and ultrafiltration, respectively. A total of 14 phenolic compounds were identified in apple juice prepared from Golden Delicious apples. The phenolic compounds were found to be based mainly on hydroxycinnamic acids (∼ 50% of total phenolics) and chlorogenic acid was found to be the major phenolic compound with its concentration as high as 465.45 mg 1⁻¹ in raw apple juice.     

T6热处理对触变锻造加低过热铸造制备的A356和A380铝合金的影响（英文）

研究T6热处理对触变锻造A356和A380铝合金的影响。采用低过热铸造(LSC)技术制备用于触变锻造的样品。为了获得等轴晶粒并防止枝晶生长,将样品在高于液相温度20°C时进行浇铸,将浇铸坯料再加热不同时间(20~80 min)后进行触变锻造,变形量为50%,再将触变锻造后的A356和A380铝合金样品进行T6热处理。用光学显微镜、能量弥散X射线谱仪、扫描电镜和布氏硬度仪对经触变锻造、固溶处理和时效处理后样品的显微组织和硬度变化进行检测。结果表明,T6热处理后合金的显微组织更均匀,并分别在A356和A380坯料中形成了新的析出相Mg_2Si和Al_2Cu。相应地,经过人工时效后,样品的硬度大幅度提高,A356铝合金的硬度达到HB 93,A380铝合金的硬度达到HB 120。     

INVESTIGATIONS ON THE SYNTHETIC AUXIN RESIDUES OF GREENHOUSE TOMATOES (LYCOPERSICON ESCULENTUM) GROWN IN TURKEY

Normal and misshapen greenhouse‐grown tomatoes (n= 100 for each group) were analyzed separately in order to compare their synthetic auxin residue contents. Sharply elongated blossom‐ends, “hook‐like” and “slice‐like” deformations were the auxin‐induced shape abnormalities most often observed. The greenhouse tomatoes were found to contain only 4‐chlorophenoxyacetic acid (4‐CPA), but no 2,4‐dichlorophenoxyacetic acid (2,4‐D) or β‐naphtoxyacetic acid (BNOA) residues. Seasonal variations in the mean 4‐CPA residues of greenhouse tomatoes were significant (p<0.05) through 1994‐97. Mean 4‐CPA residues of normal and misshapen greenhouse tomatoes were 0.323/pm0.187 mg kg^?1 and 0.363/pm0.150 mg kg^?1, respectively. The difference was not statistically significant (p>0.05). The average 4‐CPA residue in abnormally shaped fruit is greater than 0.3 mg kg^?1. While misshapen fruit always contained residues of at least 0.1 mg kg^?1, 95% of normal‐shaped fruit also contained residues exceeding 0.1 mg/kg^?1.     

THE EFFECT OF PROCESSING METHOD ON THE CHARACTERISTICS OF CARROT JUICE

ABSTRACT

The production of carrot juice using different technologies is the main subject of this investigation. Although the production and preservation of the carrot juice technology have not been improved and are not prevalent, an intensive study has been carried out on this subject recently. In this study, the effects on the yield and quality of carrot juice produced with and without total enzymatic liquefaction (Pectinex Ultra SP‐L, Novo Nordisk Ferment, Dittingen, Switzerland) as well as lactofermentation or citric acid addition have been investigated. Generally, enzymatic liquefaction of mash increased the juice yield (89.32 ± 1.17 and 90.43 ± 0.47% for lactofermented and citric‐acid‐added samples, respectively), while the control sample juice yield was found to be 59.90 ± 0.81%. Lactofermented and acid‐added samples demonstrated lower pH value. In enzyme‐treated samples, the total acidity increments were also determined. Accordingly, galacturonic acid formed after enzymatic breakdown of pectin in the raw material increased the total acidity of the samples. Magnesium contents of lactofermented juices were found to be low because lactic acid bacteria require magnesium for their growth. β‐Carotene contents have been found to be higher in both lactofermented and in nonenzyme‐treated samples.

PRACTICAL APPLICATIONS

This article describes the effects of different processing methods on the characteristics of carrot juice. It is difficult to preserve vegetable juices such as carrot juice because of their low acidity. The acidity of carrot juice (pH ～6.2) can be adjusted by the addition of citric acid or the lactofermentation method to pH 4.5. With these processes carrot juice can be preserved by pasteurization as occurs for low pH fruit juices, increasing shelf life. According to the results of this study, increasing the acidity of mash with lactofermentation or citric acid addition also increases the juice yield.

     

THE EFFECTS OF DIFFERENT INITIAL LACTOBACILLUS PLANTARUM CONCENTRATIONS ON SOME PROPERTIES OF FERMENTED CARROT JUICE

Carrot juice (Daucus carota L.) is one of the most popular vegetable juices and represents a rich source of natural β‐carotene. Vegetable juices are available either fermented or not fermented. With the production of lactofermented juices, carrot juices are microbiologically stable, delicious and potentially provide high nutritional value. In this study, Refik Saydam Kulfur Kolleksiyanu (RSKK) 1602 Lactobacillus plantarumis used as a starter culture in carrot mash. Sensory evaluation demonstrated that an initial bacteria concentration of 3 × 10⁵ cfu/g mash resulted in the most preferred fermented carrot juice. The acidity of the fermented carrot juice can be adjusted by altering the population of the starter RSKK 1602 L. plantarum culture and the 15–16 h of fermentation time. A modified Gompertz equation was selected to describe the growth curve of RSKK 1602 L. plantarum in carrot mash.     

Influence of T6 heat treatment on A356 and A380 aluminium alloys manufactured by thixoforging combined with low superheat casting

The effects of T6 heat treatment on thixoforged A356 and A380 aluminium alloys were studied. Low superheat casting (LSC) technique was carried out to prepare proper specimens for thixoforging process. The samples were poured at 20 °C above their liquidus temperatures which provided the formation of equiaxed grains instead of dendritic growth. Produced billets were reheated for varied time from 20 to 80 min and thixoforged with 50% deformation rate. After thixoforging process, the samples were T6 heat treated for both A356 and A380 alloys. The microstructural evaluation and hardness alteration of thixoforged, solution treated and aged specimens were examined comparatively by using optical microscopy, scanning electron microscopy with energy-dispersive X-ray spectroscopy and Brinell hardness equipment. T6 heat treatment provided relatively uniform microstructure with newly formed precipitates that are Mg₂Si and Al₂Cu for A356 and A380 billets, respectively. Accordingly, hardness after artificial aging was increased considerably and reached HB 93 for A356 and HB 120 for A380 alloys.