Parboiling improved oxidative stability of milled white rice during one-year storage

Parboiling was investigated to improve the long-term oxidative stability of milled white rice beyond its current application to paddy brown rice. White rice was steamed at 105°C for 20 min, 120°C for 5 min, or 120°C for 20 min without soaking in water, followed by drying at 70°C for 3 h. During oneyear storage at 25 and 4°C, acid value as an index of oxidative deterioration of rice remained relatively constant in parboiled rice samples, while significant increases were observed in raw rice with higher acid values at 25°C compared with 4°C. This indicates that the parboiling improved the oxidative stability of white rice over the long period of time even at room temperature, therefore it can be an efficient alternative to retard the oxidative deterioration of white rice.     

Oxidative stability of processed pork. Assay based on ESR-detection of radicals

The tendency to radical formation as an early event in lipid oxidation was used to characterise the oxidative stability of processed pork in an assay based on the spin trapping technique and electron spin resonance (ESR) spectroscopy. Pork cooked at different temperatures was evaluated, and it was found that heating at 95 °C resulted in higher radical formation than heating at 70 °C or at 120 °C. The tendency to formation of radicals (identified as carbon-centered radicals from the hyperfine coupling constants) was found to correlate with the rate of oxygen depletion as measured electrochemically, and the ESR assay should be further explored as a tool for the prediction of oxidative stability of meat products.     

Water‐dispersible microparticles of polyunsaturated oils

Health benefits of polyunsaturated oils are well known; nevertheless, incorporating these oils into food/feed products is not possible due to their chemical instability. Here purified fish oil with 32% (w/w) polyunsaturated fatty acids is co‐encapsulated with the antioxidant butylhydroxyanisole, into 1.0 ± 0.7 μm cellulose‐based microspheres by solvent precipitation method, at the fish oil loading content of 41% and encapsulation efficiency of 81%. Aqueous suspension of the encapsulated fish oil particles shows significantly improved oxidative stability, thermal stability, photostability and shelf‐life stability. Dry powder of the fish oil particles shows excellent shelf‐life stability. Double bond functionality of the encapsulated oil can tolerate high production temperature such as the shrimp feed production process (95 °C for 10 min) or spray dry process (outlet temperature of 120 °C). This encapsulation strategy using biocompatible cellulose polymer should enable effective and versatile applications of polyunsaturated oils in foods, feeds and cosmetics.     

牦牛酥油微胶囊的制备及特性分析

为提高传统牦牛酥油的贮藏稳定性和生物利用率，本实验以海藻酸钠、CaCl₂为复合壁材，以锐孔法制备牦牛酥油微胶囊。以包埋率为指标，通过单因素实验和正交试验确定最佳工艺参数，使用差式扫描量热仪（DSC）、热重分析（TGA）、傅里叶红外光谱（FTIR）、扫描电子显微镜（SEM）和激光粒度仪测定其理化性质，并研究微胶囊在胃肠液中的释放特性及贮藏稳定性。结果表明，当海藻酸钠浓度1.5%，CaCl₂浓度2.5%，芯壁质量比1.5:1，乳化温度50 ℃，固化时间30 min时，微胶囊包埋率最高为89.41%；含水量为5.25%、溶解度为57.22%、休止角为20.6°；平均粒径为929.773 μm，酥油在微胶囊化后热稳定性提高；释放实验表明，微胶囊在模拟胃液、肠液中释放率分别为11.52%、96.44%；贮藏实验表明，微胶囊货架期较牦牛酥油显著延长。     

温度对李果实采后品质的影响及货架期预测模型建立

目的 研究李果实采后品质变化及建立李果实采后货架期预测模型。方法 本试验设置了3种温度（4、15、25℃）,并定期测定生理生化指标。采用零级动力学模型和一级动力学模型结合Arrhenius方程建立基于品质变化的李果实采后货架期预测模型,并验证模型的预测精确度。结果 低温明显延缓了果皮强度和果肉硬度的下降和果实失重率的上升,同时也延缓了花色苷含量的积累,对总酸含量影响不明显。根据果皮强度、果肉硬度和失重率变化建立货架期预测模型,通过验证发现基于失重率变化的货架期预测模型具有最好的精确度,相对误差值低于10%。结论 货架期预测模型的建立,可快速预测果实剩余货架期,为贮藏和货架提供技术指导。     

牦牛酥油微胶囊的制备及其特性研究

为提高传统牦牛酥油的抗氧化性能,延长保质期,本文以阿拉伯胶和明胶为壁材,采用复合凝聚法对牦牛酥油进行包埋制备牦牛酥油微胶囊。以包埋率为指标,通过单因素和正交试验优化其制备工艺,并研究其理化特性、形貌结构、稳定性和模拟胃肠消化特性。结果表明,牦牛酥油微胶囊最优工艺为：芯壁比1:1.5、壁材质量分数1.5%、复凝pH4.2、复凝温度40℃,包埋率达81.39%;牦牛酥油微胶囊的平均粒径、水分含量、溶解度、休止角分别为19.728μm、3.62%、96.48%、37.7°;扫描电子显微镜和傅里叶红外光谱分析表明,牦牛酥油微胶囊表面光滑,形状结构不规则,牦牛酥油被壁材成功包埋;差式扫描量热和热重分析表明,牦牛酥油微胶囊的热稳定性较好;此外,牦牛酥油微胶囊可以实现牦牛酥油在模拟胃肠液中的控制释放,其中,人工肠液中释放率达99.74%;贮藏实验表明,微胶囊化能减缓牦牛酥油氧化速度、延长货架期。本研究为提高牦牛酥油的生物利用率提供理论依据。     

Effect of cholesterol removal on the granulation behaviour of low‐cholesterol ghee

Grain formation is one of the critical attributes affecting consumer acceptability of ghee. It was observed that both control ghee and low‐cholesterol ghee had grains of 0.236 ± 0.006 and 0.250 ± 0.002 mm size after incubation at 29 °C for 24 h, respectively. The maximum grain yield was 63 ± 2.60% and 68 ± 1.15% at 26 °C in control and low‐cholesterol ghee, respectively. Ghee grains in both the cases were stable over a temperature range of 25° to 36 °C. Time taken by both the samples for onset of nucleation was 50 min. The study revealed that cholesterol removal did not affect the crystallisation behaviour.     

Optimization of Convective Dehydration of <Emphasis Type="Italic">Beta vulgaris</Emphasis> for Color Retention

Beta vulgaris or beet root powder is a good natural food colorant since beet contains significant amount of red-colored betalain pigments. This paper reports the process optimization of drying conditions to get beet root powder with maximum retention of red color. Response surface method was used with three factors: five-level central composite design to arrive at optimum drying temperature, sample thickness, and hot air recirculation. Beet powder was evaluated to assess color retention with respect to fresh beet as a control. A 53 °C temperature and 7-mm thickness with 63% air recirculation ratio gave the best product, with 90% retention of red color having acceptable rehydration ratio and final moisture content. Using optimum sample thickness and air recirculation rate, drying process was further improved to reduce drying time and energy consumption. At different temperatures (50 to 120 °C), drying characteristics were studied. Thus, drying time of 6 h was further reduced to 4 h by applying sequential temperature gradient during drying (initial 120 °C gradually reduced to 53 °C) that also resulted in energy savings with the same degree of color retention.     

Variation in grainy texture of commercial ghee in relation to laboratory ghee and its blends†

Ghee, a major Indian dairy product, has unique pleasing flavour and granular texture. Ten samples of commercial ghee were analysed for grainy texture, fatty acid composition and melting and crystallisation behaviour. These were compared with laboratory ghee and its blends with high melting fraction (HMF) or low melting fraction (LMF). Grain size and quantity of commercial ghee ranged from 0.200 to 0.330 mm and 1 to 40%, respectively, when incubated at 29 °C for 24 h. Laboratory ghee samples showed a grain size and quantity of 0.241 mm and 42%, respectively. Commercial samples with poor granularity had a lower level of saturated fatty acids, while those with bigger grains had a higher level of palmitic acid (>35%). The ratio of unsaturated to saturated fatty acids showed significant variation in these samples. Differential scanning calorimetric analysis of the samples also showed variation in melting and crystallisation behaviour. In general, the characteristics of commercial ghee with poor granularity resembled those of laboratory ghee blended with LMF while commercial ghee with bigger grains compared well with the ghee blended with HMF.     

Evaluation of Accelerated Test Factors through the Development of Predictive Models in Vacuum-Packaged Compressed Biscuits

Analysis of the physicochemical properties, bacteria numbers, and sensory quality of vacuum-packaged compressed biscuits (VCB) was conducted at room temperature and (or) elevated temperatures to ascertain the main deterioration indicator. The acid value (AV) was determined as the deterioration index and the limiting value was 3.28 mg g^?1. The deterioration curves of VCB between 45 and 85 °C were investigated and the changes of AV followed a first-order reaction. A modified Arrhenius model was selected for shelf life prediction (SLP). For analyzing the factors associated with prediction accuracy, the R², %RMS values of the prediction model, and the prediction errors of shelf life from accelerated shelf life tests (ASLT) were evaluated. The results showed that the number of replicates was the most important factor for prediction accuracy, followed by the time intervals for sampling and the number of points fitted for determining the deterioration curve. At the appropriate sampling interval, 9 points fitted in the AV change curves with three replicates were necessary. In the experimental design of ASLT, the results indicated that the number of temperatures had the greatest impact on the accuracy and at least one low temperature close to room temperature should be used when designing ASLT. However, for a long shelf life product such as VCB which the shelf life is more than 2 years, on the premise of prediction accuracy, taking into account the test cycle and cost, a certain number of relative higher temperatures (65, 75, and 85 °C) can be used in ASLT.     

Effect of Osmotic Dehydration and Pectin Edible Coatings on Quality and Shelf Life of Fresh-Cut Melon

The aim of this work was to investigate the influence of osmotic dehydration and pectin edible coating on quality parameters of fresh-cut melon. Fruits were osmodehydrated in 40°Bx sucrose solution containing 0.5% calcium lactate or dipped in 0.5% calcium lactate solutions. Then, samples were coated with 1% pectin. Melon pieces dipped in sanitizing solution (nontreated sample) were used as control. Weight loss, respiration rate, firmness, color parameters (lightness, chroma, and whiteness index), sensory acceptance, microbial growth, and structural changes of fruits were evaluated during storage at 5 °C for 14 days. The shelf life of the control sample was limited to 9 days due to microbial growth and sensory rejection, while treated samples showed a shelf life of 14 days. Higher preservation of firmness in coated samples was attributed to the action of calcium salt on melon structure, causing a strengthening of the cell wall. Calcium lactate also inhibited microbial growth along storage, improving microbiological stability of fresh-cut melon. The use of calcium lactate dips and pectin edible coatings hindered weight loss and maintained fruit color characteristics during the storage time. However, these pretreatments probably masked melon taste, reducing the sensory acceptance scores at the end of shelf life study. The combination of osmotic dehydration and pectin coatings was a good preservation alternative for fresh-cut melon, since it improved fruit sensory acceptance, promoting the reduction of product respiration rate, as well as the maintenance of quality parameters during 14 days.     

Heat and storage effects on the flavour of peanuts

Two peanut varieties, Giza 4 and Giza 5 were subjected to different heat treatments such as drying in solar drier at air speed 0.5 and 2 m/sec with average temperature 45 and 60°C and heating in oven at 120 and 150°C. The sensory evaluation of the two varieties showed insignificant differences among varieties and heating processes. A correlation between the sensory and instrumental data was found. The high sensory scores of samples heated at 150°C were attributed to the presence of high concentration of pyrazines which were thought to contribute to flavour and aroma of fresh roasted peanut. A comparative study between the main chemical classes retained in peanut samples after storage for 3 months at room temperature showed that the aldehydes derived lipids increased significantly in the solar dried samples. The antioxidative components produced via Maillard reaction resulted in oxidative stability of the samples heated in oven     

Classification of Sunflower Oil Blends Stabilized by Oleoresin Rosemary (Rosmarinus officinalis L.) Using Multivariate Kinetic Approach

The sunflower oil–oleoresin rosemary (Rosmarinus officinalis L.) blends (SORB) at 9 different concentrations (200 to 2000 mg/kg), sunflower oil–tertiary butyl hydroquinone (SO_TBHQ) at 200 mg/kg and control (without preservatives) (SO_control) were oxidized using Rancimat (temperature: 100 to 130 °C; airflow rate: 20 L/h). The oxidative stability of blends was expressed using induction period (IP), oil stability index and photochemiluminescence assay. The linear regression models were generated by plotting ln IP with temperature to estimate the shelf life at 20 °C (SL₂₀; R² > 0.90). Principal component analysis (PCA) and hierarchical cluster analysis (HCA) was used to classify the oil blends depending upon the oxidative stability and kinetic parameters. The Arrhenius equation adequately described the temperature‐dependent kinetics (R² > 0.90, P < 0.05) and kinetic parameters viz. activation energies, activation enthalpies, and entropies were calculated in the range of 92.07 to 100.50 kJ/mol, 88.85 to 97.28 kJ/mol, ?33.33 to ?1.13 J/mol K, respectively. Using PCA, a satisfactory discrimination was noted among SORB, SO_TBHQ, and SO_control samples. HCA classified the oil blends into 3 different clusters (I, II, and III) where SORB₁₂₀₀ and SORB₁₅₀₀ were grouped together in close proximity with SO_TBHQ indicating the comparable oxidative stability. The SL₂₀ was estimated to be 3790, 6974, and 4179 h for SO_control, SO_TBHQ, and SORB₁₅₀₀, respectively. The multivariate kinetic approach effectively screened SORB₁₅₀₀ as the best blend conferring the highest oxidative stability to sunflower oil. This approach can be adopted for quick and reliable estimation of the oxidative stability of oil samples.     

Effects of temperature during processing with wine on chemical composition,antioxidant capacity and enzyme inhibition activities of Angelica Sinensis Radix

The effects of temperature (100 °C, 150 °C, 250 °C) during processing with wine on chemical composition, oil oxidative stability, inhibitory activities on acetylcholinesterase (AChE) and pancreatic lipase (PL) of Angelica Sinensis Radix (ASR), and the feasibility of melanoidins as a colour index to control the roasting intensities were investigated for the first time. The results showed that there were the highest content of ferulic acid, total flavonoids and antioxidant activity of sample roasted at 150 °C, and the sample roasted at 250 °C had the highest content of polysaccharide and total phenolics. A continued reduction in volatile content has occurred in progressive roast. The oxidant stability of oil has a slight increase along with the strength of the roasting intensities, which was higher than unprocessed ASR. Inhibitory activities on acetylcholinesterase and pancreatic lipase were decreased firstly and then increased. Melanoidins can be used as a colour indicator for controlling the thermal processing.     

Cutting Shape and Storage Temperature Affect Overall Quality of Fresh-cut Papaya cv. 'Maradol'

: The effect of cutting shape (cubes or slices) and storage temperature (5 °C, 10 °C, and 20 °C) on overall quality of fresh‐cut papaya were investigated. CO₂ production, color, firmness, total soluble solids (TSS), weight loss, overall quality, ascorbic acid, β‐carotene, and antioxidant capacity were evaluated as a function of shelf life. CO₂ production was high on day 0 for cubes and slices with an average of 150 and 100 mL/ kg/h, respectively. Storage temperature did not affect color changes; however, lower temperatures prevented loss of firmness. Fresh‐cut papaya stored at 20 °C showed the lowest TSS value and the highest weight losses. Shelf life based on visual quality ended before significant losses of total ascorbic acid, b‐carotene, and antioxidant capacity occurred. In general, quality parameters were not affected by shape. However, slices stored at 10 °C and 5 °C had a shelf life of 1 d and 2 d longer than cubes, respectively.     

Effect of antioxidant principles isolated from mango (Mangifera indica L) seed kernels on oxidative stability of buffalo ghee (butter‐fat)

A method was developed to extract and isolate the antioxidant principles, ie mainly phenolic and phospholipid classes, from mango (Mangifera indica L) seed kernels using organic solvents. The presence of at least six phenolic compounds and eight phospholipids in the isolates was confirmed by chromatographic techniques. A phenolic preparation and a phospholipid preparation were prepared separately by dissolving the isolated compounds from mango seed kernels in buffalo ghee. The phenolic preparation contained 9.6 mg% water‐extractable phenolics, 69.5 mg% total phenolics and 6.39 mg% phospholipids. The phospholipid preparation contained 155.8 mg% phospholipids, 0.11 mg% water‐extractable phenolics and 0.19 mg% total phenolics. The addition of these preparations to buffalo ghee at 5, 10 and 20% levels individually and in combination significantly increased the levels of phenolics and phospholipids respectively. Samples of buffalo ghee with added BHA contained levels of these compounds similar to that of a control sample without any other additives. The antioxidant indices calculated from the induction period of ghee samples stored at 80 ± 2 °C. in comparison with the control were, in order, 10.11 (20% phospholipid and phenolic preparation) > 8.88 (10% phospholipid and phenolic preparation) > 8.66 (20% phenolic preparation) > 6.44 (5% phospholipid and phenolic preparation) > 5.44 (10% phenolic preparation) > 4.88 (20% phospholipid preparation) > 3.00 (5% phenolic preparation) > 2.77 (10% phospholipid preparation) > 2.22 (5% phospholipid preparation) > 1.44 (0.02% BHA). This demonstrated that the phenolics and phospholipids isolated from mango seed kernel, when added jointly to buffalo ghee, helped in extending the shelf‐life of ghee. © 2000 Society of Chemical Industry     

Use of rosemary (Rosmarinus officinalis L.) leaf for improving oxidative stability of microwave‐precooked traditional Thai pork patty and its frozen storage trial

A study was carried out to assess the effects of rosemary leaf, microwave cooking time and meat particle size on the oxidative stability of Thai‐style seasoned patties. A preliminary investigation to determine the optimum marination and microwave cooking times showed that they were, respectively, 120 and 12 min. These conditions were used to prepare patties for the main study, which showed that patties formed with smaller meat particles (1.5 vs. 4.7 mm) were more stable with regard to oxidative stability. Increased TBARS formation was observed for increasing microwave cooking time. Finally, patties with added rosemary leaf (3.2% by weight of the meat) were significantly more stable to oxidation than the controls and had a shelf life of 3–4 months in frozen storage (?18 °C). The microwave cooking time over 12 min seems excessively long.     

Quality improvement and extension of shelf life by 1-methylcyclopropene in plum as affected by ripening stage at harvest

Plum (Prunus domestica L. cv. ‘President’) fruits were harvested at two pre-climacteric stages of ripeness (stage 1 and stage 2), and then treated with 1-methylcyclopropene (1-MCP) at two doses (0.3 and 0.5 μl l⁻¹) followed by 1, 2, 3, 4 and 5 weeks of cold storage and their respective 7 days of shelf life at 20 °C. Both 1-MCP doses were effective in terms of ethylene inhibition during shelf life after cold storage, for both ripening stages. Similarly, lower weight losses, delayed colour changes, reduced softening rate and diminished ripening index were found in 1-MCP treated plums than in controls at both stages of ripeness. Hence, during cold storage and shelf life, the efficacy of 1-MCP on ethylene production, weight loss, pulp firmness and ripening index was dose-dependent, while for colour and respiration rate the dose-dependence was only found during shelf life. The storability of 1-MCP treated plums could be extended up to 4 weeks of cold storage plus 7 days at 20 °C, and only up to 1 week of cold storage plus 7 days at 20 °C for controls. Then, 1-MCP is an effective tool for quality improvement and extension of shelf life in plums, and fruit might be harvested in stage 2 of ripening, at which the most desirable organoleptic attributes had been developed on tree.     

Comparative studies of oxidative stability of edible oils by differential scanning calorimetry and oxidative stability index methods

A comparative study was conducted to determine the oxidative stability of twelve different edible oils with two different instruments: a differential scanning calorimeter and an oxidative stability index (OSI) instrument. The OSI instrument temperature was set at 110 °C. The differential scanning calorimetry (DSC) technique involved oxidation of oil samples in an oxygen-flow DSC cell. The DSC cell temperature was set at four different isothermal temperatures: 110, 120, 130 and 140 °C. A dramatic increase of evolved heat was observed with the appearance of a sharp exothermic curve during initiation of the oxidation reaction. The oxidative induction time (T₀) was automatically determined by extrapolation of the downward portion of the DSC oxidation curve to the time axis. There was a good correlation (P<0.0001) between the DSC T₀ and OSI values. The decrease in log₁₀ (T₀) with increasing DSC isothermal temperature was best fitted by a linear equation. DSC evidently provides a convenient way to determine the oxidative stability of various edible oils.