Influence of Modified Atmosphere Packaging and Osmotic Dehydration on the Quality Maintenance of Minimally Processed Guavas

ABSTRACT: The quality of minimally processed guavas ( Psidium guajava L.), osmotically dehydrated and packed under passive modified atmosphere, was evaluated during 24 d of storage at 5 °C. Modified atmosphere packaging (MAP) in polyethylene terephthalate (PET) containers had a strong influence on color preservation and weight loss of the guavas. Significant changes in the texture were found due to osmotic dehydration, but the color of the fresh fruit remained unchanged. Osmotically dehydrated guavas stored in MAP showed good microbial conditions during storage. The combination of storage temperature, modified atmosphere packaging, and the osmotic dehydration process maintained the quality of the guavas during 24 d of storage.     

Osmotic Dehydration and Vacuum Impregnation on Physicochemical Properties of Chilean Papaya (Carica candamarcensis)

ABSTRACT: The effect of osmotic dehydration (OD) at atmospheric pressure and vacuum impregnation (VI) treatments on some physiochemical parameters of papaya (aw, pH, color, firmness, and microstructure) was analyzed. Osmotic treatments were carried out on papaya with 55°Brix and 65°Brix sucrose solutions at 30 °C. VI with 65°Brix osmotic solution was the most effective in reducing aw due to the highest sucrose gain during osmotic treatment. Color differences were associated to loss of clarity in line with transparency gain. Scanning electron microscopy observations show that osmotic dehydration caused shape changes and size reduction of papaya cells; also differences in microstructural features were observed between OD-treated and VI-treated samples. Moreover, the largest firmness observed in VI samples compared with OD treatments was associated with the thickness of the middle lamella between cells, which was greater in VI than OD treatments. Improvement in texture and palatability of papaya was obtained with VI rather than OD treatment compared with fresh papaya.     

Total Heme and Non-heme Iron in Raw and Cooked Meats

ABSTRACT: This study provides data on the total heme and non-heme iron contents in poultry (chicken, turkey), beef, veal, lamb, horse, ostrich, rabbit, and pork meat cuts. The effect of cooking on heme iron content was also studied. Total iron and heme iron contents markedly differed between muscles in poultry. Heme iron in red meats ranged from 72 to 87%. Heme iron in rabbit and pork was 56 and 62% of total iron. Heating decreased heme iron, the severity of the losses depended on cooking methods: in poultry, losses ranged from 22 to 43%; less severe impact was detected in pan-cooked meat, where the losses ranged from 1 to 24%.     

Microbial Population of Shredded Carrot in Modified Atmosphere Packaging as Related to Irradiation Treatment

Shredded carrots in modified atmosphere packaging were treated with low-dose irradiation of 0.5 kGy in order to determine whether additional reduction of microbial population would be achieved for carrots previously treated with chlorine. Commercially prepared shredded carrots treated with irradiation had a mean microbial population of 1300 CFU/g at the expiration date (9 days after irradiation) compared with 87,000 CFU/g for nonirradiated, chlorinated controls. Oxygen content of the headspace gas and ethanol content of the carrots were not significantly affected. Irradiation appears to be a suitable technology for shredded carrots.     

再制干酪贮藏期间的物理及化学变化

再制干酪往往被认为是一种保质期较长的、稳定的干酪食品。事实上，再制干酪即便不被微生物污染，室温下的保质期也只有几个月。贮藏期间，再制干酪的质地和风味都慢慢改变，本文阐述了引起储藏期间再制干酪质地和风味变化的主要原因，对引起这些变化的因素加以分析．并概括了国外关于再制干酪储藏期的研究进展。通过对再制干酪贮藏期质地变化的研究，将有助于干酪生产者更好的预测和控制产品贮藏期间的质量。     

Improvement of frozen banana (Musa cavendishii, cv. Enana) colour by blanching: relationship between browning, phenols and polyphenol oxidase and peroxidase activities

 Browning in banana (Musa cavendishii, cv. Enana) processed products is a result of phenol oxidation catalysed by polyphenol oxidase (PPO) and peroxidase (POD) or of other non-enzymatic reactions (Maillard and Strecker mechanisms). Microwave and steam blanching significantly reduced PPO and POD activities and phenol levels in banana flesh, steam blanching being the most effective method for enzyme inactivation. Freezing/thawing processes produced a significant increase in phenol levels in all samples, due to cellular breakdown. After microwave heating browning processes occurred while steam-treated samples did not exhibit a significant colour change. Extractable PPO and POD activities in all banana samples increased as a consequence of freezing/thawing: steam-blanched slices exhibited lower residual activities. High correlations occurred between phenols and browning (r=0.86) in control samples. Blanched samples (microwave or steam) only exhibited correlations between PPO (r=0.80) and POD (r=0.80) activities and browning. Received: 22 February 1996     

一种改进的理想滤波器方位模糊抑制方法

合成孔径雷达(SAR)图像的方位模糊问题是由于方位向欠采样引起的,其严重影响判读人员对SAR图像的解译.阐述了方位模糊的来源及其建模,进一步总结了利用理想滤波器进行方位模糊抑制的方法及其局限性,针对该方法的参数失配问题,从主像和模糊像在方位向和距离向上的偏移距离的角度出发,提出并明确分块处理大区域方位模糊抑制的思路及分...     

Enhancement of γ-aminobutyric acid (GABA) in Nham (Thai fermented pork sausage) using starter cultures of Lactobacillus namurensis NH2 and Pediococcus pentosaceus HN8

The aim was to produce Nham that was enriched with γ-aminobutyric acid (GABA); therefore two GABA producing lactic acid bacteria (Pediococcus pentosaceus HN8 and Lactobacillus namurensis NH2) were used as starter cultures. By using the central composite design (CCD) we showed that addition of 0.5% monosodium glutamate (MSG) together with an inoculum size of roughly 6 log CFU/g of each of the two strains produced a maximal amounts of GABA (4051 mg/kg) in the ‘GABA Nham’ product. This was higher than any current popular commercial Nham product by roughly 8 times. ‘GABA Nham’ with the additions of both starters and MSG (T_SM) supported maximum populations of lactic acid bacteria (LAB) with a minimum of yeasts and no staphylococci or molds when compared to the controls that had no addition of any starters or MSG (T_NN), or only the addition of MSG (T_NM), or with only the starter (T_SN). Based on proximate analysis among the Nham sets, ‘GABA Nham’ was low in fat, carbohydrate and energy although its texture and color were slightly different from the control (T_NN). However, sensory evaluations of ‘GABA Nham’ were more acceptable than the controls and commercial Nham products for all tested parameters. Hence, a unique novel ‘GABA Nham’ fermented pork sausage was successfully developed.     

复合乳化剂防止常温贮藏再制干酪油脂析出的研究

为解决常温贮藏再制干酪加工过程及贮藏期间的油脂析出问题,本研究以油析性为评定指标,从6种乳化剂中筛选出4种效果较好的乳化剂,在确定常温贮藏再制干酪最适亲水亲油平衡值(HLB值)后,根据HLB值将不同乳化剂进行复配,得到了1种最佳组合的复合乳化剂配方.结果表明,最适HLB值为12.2,复合乳化剂最佳配比(均为质量分数):14％单甘脂,30％六聚甘油单硬脂酸酯,56％的蔗糖脂肪酸酯,乳化剂总用量为0.4％.同时将样品置于(22±2)℃条件下,贮藏90 d,定期检测产品油性变化,均小于对照组,且差异显著(P＜0.05),说明添加该复合乳化剂有效.