Firmness Retention in Pickled Peppers as Affected by Calcium Chloride, Acetic Acid, and Pasteurization

Critical factors influencing firmness retention in pickled peppers were studied. The addition of CaCl, (0.2%, w/v, optimum) to whole, pickled‘Red Cherry’peppers increased firmness retention as determined by a puncture test using an Instron Universal Testing Machine. Pasteurization reduced firmness in the absence, but not in the presence, of added CaCl₂. CaCl₂ significantly (P ≤0.01) reduced softening during storage of‘Red Cherry’peppers at higher temperatures (36.7, 46.7°C), and resulted in a slight increase in firmness at 26.7°C. CaCI₂ did not significantly (P≥ 0.05) improve firmness retention in‘Jala-peno’peppers, but resulted in greater uniformity of firmness. CaCI, also improved firmness retention in pickled cucumbers. Firmness of unpasteurized peppers and cucumbers was not influenced significantly (P ≥0.05) by acetic acid concentrations of 2, 3 or 4%.     

Muscle Firmness and Structure of Raw and Cooked Arrow Squid Mantle as Affected by Freshness

Changes in firmness and structure of arrow squid (Loligo bleekert) mantle muscle during refrigeration (5°C) were studied. Shear force of raw mantle decreased sharply between 3 and 9 h refrigeration after killing. Light microscopic observations showed many pores between muscle cells in the softened raw samples. Transmission electron microscopic observations suggested that the spaces appeared as a result of detachment of muscle cells from connective tissues. After cooking the stored raw muscle, the shear force and muscle structure were almost the same for samples with different storage times. Freshness had an influence on raw squid muscle firmness and structure but not on cooked muscle.     

Firmness and Cell Wall Characteristics of Pasteurized Jalapeño Pepper Rings as Affected by Calcium Chloride and Rotary Processing

Rotary processing resulted in more uniform heat penetration and texture retention throughout the container than resulted after nonagitated processing. Localized softening in nonagitated peppers was due to prolonged heating at the top of the container, which hydrolyzed large molecular weight pectic substances (chelator and nonextractable) to more soluble forms. Calcium improved the texture by maintaining greater levels of insoluble pectic substances (chelator, dilute alkali and nonextractable) and reducing pectin solubilization. The combination of rotary processing and calcium chloride treatment resulted in a product with fresh-like, uniform texture throughout the container.     

Firmness and Cell Wall Characteristics of Pasteurized Jalapeño Pepper Rings Affected by Calcium Chloride and Acetic Acid

Pepper rings packed in brine containing CaCl₂ were firmer, had higher bound calcium, chelator soluble pectin and pectin DE, and less water-soluble pectin (WSP) than peppers packed in brine containing no CaCl₂. Pepper rings packed in low acid brines (1% and 1.2% acetic acid) were firmer and had less WSP than those packed in high acid brine. Those samples (4% acetic acid) resulted in softening and pectin solubilization, but CaCl₂ resulted in less softening. Monosaccharide composition of cell walls was not affected by CaCl₂ or acetic acid. Firmness retention in CaCl₂ treated samples was probably due to greater association between calcium ions and pectic substances, which resisted acid hydrolysis.     

基于高光谱成像的贵长猕猴桃硬度快速预测

为了提高猕猴桃硬度预测的效率。应用可见/近红外(390～1030 nm)高光谱成像系统获取贵长猕猴桃的高光谱图像信息,并提取每个样品感兴趣区域的反射光谱,采用标准正态变换消除原始反射光谱中的噪声干扰;基于竞争性自适应重加权(competitive adaptive reweighted sampling,CARS)与连续投影算法筛选特征变量,建立误差反向传播神经网络和多元线性回归(multi linear regression,MLR)模型检测贵长猕猴桃硬度。结果表明：应用CARS从256个变量中筛选了35个特征变量,运算效率提升了近11倍(即运算时间从5.84 s降到了0.54 s);构建的CARS-MLR检测模型具有较大的r_c=0.95和r_p=0.92,较小的RMSEC=1.65 kg/cm²和RMSEP=1.99 kg/cm²,且RPD值(2.47)大于2,表明CARS-MLR模型具有非常好的检测性能,利用高光谱成像技术以及化学计量学可以实现贵长猕猴桃硬度的快速无损检测。     

Size Reduction and Calcium Release of Fish Bone Particles During Nanomilling as Affected by Bone Structure

Three types of fish bones including fish skull, rib, and backbone were cooked at 120 °C for 20 min to remove tissues and impurities. The fish bones were minced and ground into microscaled particles before treated in a high-energy wet ball mill to obtain nanoparticles. The effects of bone structure on size reduction of fish bone particles during nanomilling and the calcium release properties were investigated. The results showed that fish rib has higher elasticity modulus than fish skull and fish backbone due to its highly ordered structure. Prior to nanomilling of ground fish bones, the particle size of the skull was the greatest followed by backbone and rib. The mean particle size and calcium release were not significantly different after 8-h nanomilling. However, the size reduction and calcium release rates of the nanoparticles were similar between fish skull and backbone while the fish rib had the lowest values in both categories. The kinetics of size reduction during nanomilling and the calcium release properties of the nanoparticles were well described with the first-order exponential decay function and first-order kinetic function, respectively. Correlation analysis indicated that among all mechanical properties, elasticity modulus of fish bone, to the highest degree, determined their size reduction rate and calcium release rate during nanomilling.     

Firmness and Cell Wall Characteristics of Pasteurized Jalapeño Pepper Rings as Affected by Preheating and Storage

Changes in cell wall pectic substances, degree of pectin methylation, bound calcium and firmness were determined in preheated and nonpreheated fresh pack jalapeño pepper rings stored for 5 mo. Pepper rings preheated for 60 min at 50°C in a brine solution (8% NaCl and 0.2% CaCl₂, were firmer, had more nonextrctable pectins (NXP), more bound calcium, less water-soluble and chelator-soluble pectins (CSP), and less pectin methylation than nonpreheated pepper rings. The greater formation and maintenance of nonextractable pectins, which resisted acid hydrolysis during pasteurization and storage is probably an important factor in firming.     

Association of Zinc with Soy Proteins as Affected by Heat and pH

The effect of heat on the chemical association of ⁶⁵Zn with proteins and of pH on the solubility of proteins, phytic acid, zinc, and their complex formation were studied in soybeans grown hydroponically and intrinsically labeled with ⁶⁵Zn. ⁶⁵Zn association with soy proteins was not affected by autoclaving. Zinc was not covalently associated with the major soy proteins, 11S and 7S. Protein, phytic acid and zinc content of the raw soyflour was determined at pH range 3.5–12 before and after dialysis. pH had only a slight effect on zinc solubility. Protein-zinc-phytate complex formation was maximum in the pH range 7.5–10.5.     

Physicochemical Properties of Surimi Seafood as Affected by Electron Beam and Heat

Physicochemical changes of surimi seafood under electron beam (e‐beam) and heat were investigated. Heat caused color browning and texture softening. E‐beam (up to 4 kGy) deteriorated neither color nor texture when the sample temperatures were between 5 and 23°C. However, firmer texture was measured when samples were treated by e‐beam while frozen. None of the treatments changed rancidity of surimi seafood within the parameters tested. Heat, as compared with e‐beam, generated the same headspace volatiles, however, to a greater extent. E‐beam was determined to be an excellent pasteurization alternative for surimi seafood in terms of retention of fresh‐like physicochemical attributes.     

Zinc, Iron and Copper Availability as Affected by Orthophosphates, Polyphosphates and Calcium

Male weanling tats were fed an adequate diet supplemented with 0.42% P from either hexametaphosphate or orthophosphate, each at two levels of Ca intake (0.53% or 1.06%). Polyphosphates represented 13% of the total fecal phosphorus at the 0.53% Ca intake; this fraction was increased to 27% at the 1.06% Ca intake. Hexametaphosphate caused a 15% increase in fecal iron, a 12% decrease in liver iron and a 15% decrease in fecal zinc losses. These effects were markedly enhanced by supplemental Ca. Orthophosphate was without effect at the 0.53% Ca intake, but caused an 11% increase in fecal zinc losses at the 1.06% Ca intake.     

Gelation Profiles of Yogurt as Affected by Heat Treatment of Milk

Milk was heated at 140°C for 6 s (UHT), 98°C for 1.87 min (HTST) and 85°C for 10 min (vat-pasteurized), homogenized, inoculated with yogurt culture, and incubated at 45°C. During incubation, pH, ionic Ca, and viscosity changes were continuously monitored by interfacing to a microcomputer. Samples for transmission electron microscopy were taken at selected pH intervals.Acid fermentation of milk was a multistage process comprising 1) an initial lag period of low viscosity; 2) a period of rapid viscosity change, and 3) a stage of high constant viscosity. The shapes of the viscosity versus incubation time curves were the same for all heat treatments differing only in the extent of viscosity change in stage 2. A microstructural study of UHT milk indicated that at pH 5.1, casein micelles appeared to dissociate into subparticles of approximately 30 to 40 nm diameter. By pH 4.8, subparticles reassociated into large casein aggregates of nonspecific shape and dimensions. Micellar dissociation was thought to be influenced by conversion of colloidal Ca to ionic Ca.     

Structure and Composition of Mushrooms as Affected by Hydrogen Peroxide Wash

An experimental H₂O₂/browning inhibitor wash treatment and its effect on mushroom structure and composition were studied. Experimentally washed mushrooms ( Agaricus bisporus ) were compared with conventionally washed mushrooms and untreated controls. Examination by scanning electron microscopy showed damage to hyphae producing a matted appearance at the pileus surface with both experimental and conventional washed samples. Mushrooms after the experimental wash had an elevated sodium content from the sodium erythorbate browning inhibitor but contained no H₂O₂ residue. In pileus tissue, soluble phenol levels were higher and the content of free amino acids was lower in mushrooms after the experimental wash. No other notable compositional differences or adverse effects of treatment on quality were found.     

Quality and Nutritional Status of Fresh-Cut Tomato as Affected by Spraying of Delactosed Whey Permeate Compared to Industrial Washing Treatment

The aim of this study was to examine the applicability of delactosed whey permeate (DWP) treatment on preserving the quality and antioxidant attributes of fresh-cut tomato. Tomatoes were treated with 3% DWP by dipping, spraying and a combination of both, stored at 4?°C for 10?days and compared with the industrial standard, chlorine. The combination of dipping and spraying of DWP showed the best results for all the markers tested. The combined treatment of dipping and spraying of DWP significantly lowered total counts (??1.0 log cfu/g), yeast and moulds (??1.2 log cfu/g), inhibited the loss of firmness (25%) and reduced POD activity (15%) of the tomato slices after 10?days compared to the chlorine treatment. Moreover, DWP-treated tomatoes maintained significantly (p?<?0.05) higher levels of vitamin C, total phenols and antioxidant activity (DPPH) than the chlorine-treated samples during storage. Sensory scores confirmed that DWP-treated tomatoes retained better aroma and texture. Also, the appearance and overall acceptability were higher than chlorine-treated tomatoes. Thus DWP treatment has potential to extend the shelf life of fresh-cut tomatoes.     

猕猴桃低温贮藏期间硬度与化学品质的相关性研究

作者对低温冷藏期间的猕猴桃果实进行硬度的穿刺测试和主要化学指标的测定。并对贮藏期间的化学指标进行主成分分析，提取第一主成分(“品质因了”)，“品质因子”综合了所测定的7个化学品质指标的信息。“品质因子”与果肉硬度的相关性分析表明，两者呈三次多项式关系，拟合度高达0．988。果肉硬度指标能反映果实的内部化学品质，可以通过硬度对猕猴桃果实的贮藏品质进行综合评价。     

Quality of Fresh-cut Apple Slices as Affected by Low-dose Ionizing Radiation and Calcium Ascorbate Treatment

ABSTRACT: Although ionizing radiation effectively inactivates food-borne bacterial pathogens in fresh-cut fruits and vegetables, it may adversely affect product quality. In this study, the effects of calcium ascorbate (CaA) and ionizing radiation on quality of 'Gala' apple slices under modified atmosphere packaging were investigated. 'Gala' apple slices, treated with water or 7% CaA followed by either nonirradiation (0 kGy) or irradiation at 0.5 and 1.0 kGy, were stored at 10°C for up to 3 wk. The titratable acidity, pH, firmness, ascorbic acid content, color, and microflora population were measured weekly throughout storage. Irradiation did not affect titratable acidity and pH of sliced apples. Fruit slices softened during irradiation and storage, but this decrease in firmness during storage was reduced by the CaA treatment. Although the ascorbic acid content of apple slices treated with CaA decreased rapidly during storage, the ascorbic acid content was always higher in those treated samples than in the apple slices treated with water. Irradiation decreased both L * and hue values of apple slices. Hue values decreased during the entire storage period while L * increased during the 1st wk of storage, then decreased between 1 to 3 wk of storage. CaA increased L * and hue values of apple slices, suggesting CaA reduced browning, even in irradiated samples. The microflora population of apples slices was not affected by CaA, and CaA treatment did not alter the reduction in microflora by irradiation. The combination of CaA and irradiation enhanced microbial food safety while maintaining quality of fresh-cut apple slices.     

Recrystallization in Sugar/Stabilizer Solutions as Affected by Molecular Structure

The influence that a range of polysaccharides (galactomannans) had on ice recrystallization was determined. The concentration dependence of the recrystallization inhibition occurring with locust bean and guar gums was determined. The degree of galactose substitution in a range of enzyme modified guars was dominant in the effect of a galactomannan to inhibit recrystallization. The fine structure of the substituents were less important. Where the galactose content of comparable polysaccharides was similar the fine structure became dominant. The influence of sugar size on recrystallization was also investigated. Increasing molecular weight resulted in reduced recrystallization rates. The observed rates appeared to follow Williams -Landell-Ferry kinetics.     

Yield and Quality of Tofu as Affected by Soybean and Soymilk Characteristics. Calcium Sulfate Coagulant

Nine light hilum soybean (Glycine max (L.) Merr.) varieties were used to study the characteristics of soybeans and soymilk that affect the yield and quality of tofu coagulated with calcium sulfate. The yield of tofu was not affected by the size of soybeans. Soybean varieties high in protein, fat and phosphorus contents produce tofu with higher protein, fat and phosphorus contents. Two models for predicting the yield of tofu were proposed. According to model one, soymilk with higher pH and total solids gives a higher yield of tofu. According to model two, soybeans high in protein and ash and low in phosphorus give a higher yield of tofu.