Residual gas and storage conditions affect sensory quality of diced pears in flexible retortable pouches

Diced pears packed in flexible retortable pouches were manufactured to obtain packages with 10, 15, 20 and 30 cm³ residual gas, then stored at 4.4, 26.7 and 37.8 °C for six months. The 2-furaldehyde and 5-hydroxymethyl-2-furaldehyde values increased and pears turned darker, softer, more homogeneous in shape/size, less fruity in flavor and aroma, and less acceptable to consumers over time. Elevated temperatures and high residual gas levels were particularly detrimental to pear quality. Highest quality was maintained for 6 months when pears packaged at any residual gas level were stored at 4.4 °C. Acceptable quality was maintained for 6 months in pears packaged with less than 30 cm³ residual gas, stored at 26.7 °C. Pear quality declined most rapidly at 37.8 °C, 30 cm³ residual gas. Residual gas volume of 15 cm³ should not be exceeded to maintain highest quality and acceptability of diced pears packed in flexible retortable pouches.     

Chemical and colour changes related to the use of sorbates and ascorbic acid in pickled cucumbers and caperberries during long‐term storage

The evolution of two additives, potassium sorbate and ascorbic acid, during long‐term storage of pickled vegetables, as well as the impact of these additives on product colour, was investigated. For this investigation, cucumbers and caperberries packed in both glass bottles and plastic pouches were used. In general, the added sorbate level remained unchanged during long‐term storage irrespective of the packaging material. However, the ascorbic acid gradually disappeared at a significantly higher rate in plastic than in glass containers, and its level was higher in caperberries than in cucumbers. In the latter, the presence of sorbate caused a higher degradation rate of ascorbic acid compared to the absence of sorbate. Ascorbic acid had a protective effect against surface colour degradation in cucumbers packed in plastic pouches, whereas sorbate enhanced such degradation. However, in both pickled vegetables, ascorbic acid degradation had a significant impact on brine browning, particularly in plastic pouches.     

Browning,polyphenol oxidase activity and headspace gas composition during storage of minimally processed pears using modified atmosphere packaging

Modified atmosphere packaging was used to prevent browning of minimally processed Conference pears, thus extending their shelf‐life. Colour changes as well as PPO activity were strongly influenced by the package headspace gas composition, which was determined by the packaging conditions. The initial colour of minimally processed pears was preserved for several weeks under cold storage in plastic pouches of very low O₂ permeability and an initial atmosphere of 100% N₂. A fractional conversion kinetic model fitted the experimental browning data with high accuracy. Colour degradation (ΔE*) of minimally processed pears occurred exponentially (k_ΔE = 0.019–0.077 day^?1) owing to changes in lightness (k_L = 0.021–0.07 day^?1). In contrast, PPO exhibited a linear increase in activity which could be related to the availability of O₂ in the package headspace. © 2002 Society of Chemical Industry     

Evaluation of heat and oxidative damage during storage of processed tomato products. I. Study of heat damage indices

The evolution of heat damage during storage of tomato pulp, puree and paste was studied by accelerated aging tests. Heat damage indices—5‐hydroxymethyl‐2‐furfural (HMF), furosine and colour changes (ΔE)—were evaluated for tomato products stored at 30, 40 and 50 °C for up to 90 days. Furosine and ΔE values increased following pseudo‐zero‐order kinetics, and the higher the solid content of the products, the higher were the rate constant values. HMF formation followed pseudo‐first‐order kinetics in tomato pulp and pseudo‐zero‐order kinetics in puree and paste samples. Data show that heat damage reactions in tomato products proceed even at room temperature, and the kinetic model provided can be used to predict changes occurring during shelf‐life. © 2002 Society of Chemical Industry     

Effect of packaging materials and storage temperature on the quality of sour cherry nectar

The purpose of this research was to determine the effects of the packaging materials and size on the stability of monomeric anthocyanins, polyphenols, antioxidant activity, ascorbic acid, colour index and hydroxyl methyl furfural (HMF) during the 12‐month shelf life of sour cherry nectars at 4 °C and 20 °C. Sour cherry nectars were aseptically filled out into packaging of different sizes and materials. The packaging included cartons of two different sizes (200 and 1000 mL) and aluminium cans (330 mL). Results showed that the nectars were of better quality when stored at lower temperatures. HMF generally increased significantly for all nectars during storage. Conversely, the total polyphenol content and the antioxidant activity of the nectars stored in aluminium cans and the larger‐sized carton packaging decreased during storage. Lower anthocyanin loss and colour change were found in the nectars stored in aluminium cans. However, the better packaging material was found to be the large‐sized carton package when HMF was analysed.     

鸡毛菜的品质动力学分析及货架期预测模型

为探讨鸡毛菜贮藏过程中的品质变化,测定贮藏在278、283、288 K和293 K 4 个温度条件下的鸡毛菜的叶绿素和还原型抗坏血酸含量,进行动力学分析、货架期预测和感官评价,并采用Arrhenius 方程对速率常数k和温度进行非线性拟合,建立包含有货架期、温度和品质指标的鸡毛菜货架期预测模型。结果表明,在研究的温度范围内,鸡毛菜贮藏的温度越低,叶绿素和还原型抗坏血酸降解速率越慢,零级规律比一级动力学分析更适合描述叶绿素和还原型抗坏血酸的降解,还原型抗坏血酸和叶绿素降解的活化能Ea分别为85.27、93.27 kJ/mol。以叶绿素损失20%为终点得到的货架期更接近感官评分终点为3.5 分得到的货架期,此时还原型抗坏血酸损失超出20%。因此应根据实际情况综合选择货架期判定特征指标和终点值,从而获得较高的货架期预测精度。     

Evaluation of heat and oxidative damage during storage of processed tomato products. II. Study of oxidative damage indices

Tomato products (pulp, puree and paste) submitted to accelerated aging (30, 40 and 50 °C for 3 months) were studied to evaluate variations in the kinetics of the degradation of antioxidants and antioxidant activity. The carotenoids lycopene and β‐carotene, ascorbic acid, rutin and total phenolics were analysed. The antioxidant activity was measured using (a) the xanthine oxidase (XOD)/xanthine system, which generates superoxide radicals and hydrogen peroxide, and (b) the linoleic acid/CuSO₄ system, which promotes lipid peroxidation. The ascorbic acid content decreased even at 30 °C, following pseudo‐first‐order kinetics, with an activation energy of 105 200 J mol^?1 for tomato pulp and 23 600 J mol^?1 for tomato paste. The lower the initial ascorbic acid content, the higher was the degradation rate. Variations in phenolic compounds occurred at 40 °C and higher, following pseudo‐zero order kinetics. The antioxidant activity of the hydrophilic fraction of the tomato products depended on both antioxidant degradation and the Maillard reaction and could not be described by a kinetic model. The β‐carotene content decreased even at 30 °C, whereas the lycopene content was stable in all samples. The antioxidant activity of the lipophilic fraction of the tomato products decreased following pseudo‐first order kinetics, with an activation energy of 22 200 J mol^?1 for tomato pulp and 20 200 J mol^?1 for tomato paste. It is concluded that significant ‘oxidative damage’ can occur in tomato products during their commercial shelf‐life. Copyright © 2003 Society of Chemical Industry     

Changes in Bioactive Compounds, Antioxidant Activity and HMF Formation in Rosehip Nectars During Storage

In this study, reaction kinetics of ascorbic acid degradation and hydroxymethylfurfural (HMF) formation in glass-bottled and cardboard-packaged rosehip nectars stored at 25, 35 and 45 °C were evaluated. Variations of total phenolics, total carotenoids, and antioxidant activity of samples were also evaluated. HMF formation followed a zero-order reaction, while a first-order reaction model was fitted to ascorbic acid degradation. The activation energies for ascorbic acid degradation and HMF formation were found as 56–63.9 and 42.9–53.0 kJ mol^?1, respectively. During storage, total phenolics content of rosehip nectars were decreased significantly. However, changes in the total carotenoids of rosehip nectars during storage were not statistically significant. Decreases in the antioxidant activity of glass-bottled rosehip nectars during storage at all applied temperatures were found statistically significant, whereas no significant variations were observed in the antioxidant activities of cardboard-packaged rosehip nectars.     

The effects of natural antioxidants and lighting conditions on the quality characteristics of gilt‐head sea bream fillets (Sparus aurata) packaged in a modified atmosphere

The effects of lighting conditions and the application of natural antioxidants (rosemary extract and ascorbic acid) on the shelf‐life of gilt‐head sea bream fillets (Sparus aurata) packaged in a modified atmosphere (MAP) and stored at 1 ± 1 °C were studied. Lighting with low‐UV colour‐balanced lamps led to an extension of shelf‐life compared with that under supermarket fluorescent tubes, as assessed by lipid oxidation (TBARS value) and sensory evaluation. The application of antioxidants to the surface of MAP fillets delayed lipid oxidation besides improving the sensory quality. Rosemary extract was more effective than ascorbic acid in delaying lipid oxidation under both kinds of lighting. The effect of ascorbic acid was greater in the samples illuminated by low‐UV tubes than in those stored under conventional lighting. However, the effectiveness of rosemary extract was similar in both kinds of lighting conditions. Copyright © 2004 Society of Chemical Industry     

Spanish‐style green table olive shelf‐life

Changes in the physicochemical and sensory characteristics of commercial whole, pitted and stuffed with pepper, garlic or anchovy paste Spanish‐style green table olives of the Gordal, Manzanilla and Hojiblanca cultivars were studied during a three‐year period. No olives developed any spoilage during this period, and at the end of it, all presentations were classified as ‘extra’ according to the sensory evaluation methodology issued by the International Olive Council. Throughout the shelf‐life, surface colour index and firmness of the olives degraded in accordance with a first‐order kinetics, while a gradual browning of the cover brines was observed; however, products added with ascorbic acid maintained a stable colour, while those with calcium content showed reduced firmness degradation. No significant changes in most of the sensory characteristics were observed by the panel test during shelf‐life and only slight changes in firmness, and surface colour were noticed in samples with significant differences in these attributes when measured instrumentally.     

Derivative spectrophotometric determination of 5‐(hydroxymethyl)‐2‐furaldehyde (HMF) and furfural in Locust bean extract

Furfural and 5‐(hydroxymethyl)‐2‐furaldehyde (HMF) are useful indicators of accurate storage temperature of food samples. A first derivative spectrophotometric method was developed for the determination of the furfural and HMF level in Locust bean pekmez. In addition, the levels of the furfural and HMF were investigated during Locust bean pekmez preparation. The recoveries were generally nearly 100%. This method is also rapid and accurate and results in economical analyses of furaldehydes.     

Effect of storage on non‐enzymatic browning of liquid infant milk formulae

Furfural, hydroxymethylfurfural (HMF), furosine, lactulose, ascorbic acid and absorbance at 284 and 420 nm (A₂₈₄ and A₄₂₀) were all determined in two types of liquid infant formula prepared with different processing protocols. These browning indicators were used to assess the effects of storage and modified atmosphere on the shelf‐life of infant formulae. The study was carried out at 20 and 55 °C for 15, 30 and 90 days. At 20 °C, slight browning was observed and could be evaluated by furosine, furfural and total HMF indicators. At 55 °C, formula type A (pasteurised, spray‐dried and reconstituted) showed more browning in nitrogen storage conditions than did type B. Furfural, HMF, lactulose, A₂₈₄ and A₄₂₀ are useful indicators to control the extent of browning reactions in adverse storage conditions. © 2002 Society of Chemical Industry     

Effect of Initial Dissolved Oxygen Levels on the Degradation of Ascorbic Acid and the Browning of Lemon Juice during Storage

The effect of different initial dissolved oxygen concentrations (0.41, 1.44, and 3.74 mg/L) on rate of deteriorative quality changes [ascorbic acid degradation, browning, hydroxymethylfurfural (HMF) and furfural production) in lemon juice stored at 36°C was investigated. No significant effects on rate of ascorbic acid degradation and furfural formation could be attributed to the different oxygen levels. Degradation of ascorbic acid appeared to be predominantly anaerobic. Lag period before browning increased depended on oxygen level. Zero-, first- and second-order kinetic models were fitted to various degradative reactions occurring in lemon juice during storage. Highly significant correlations were obtained between browning index, HMF, and furfural formation, suggesting that all three would be suitable as chemical indices of storage temperature abuse in lemon juices.     

Degradation kinetics of ascorbic acid in encapsulated spray-dried honey powder packaged in aluminium laminated polyethylene and high-density polyethylene

The present study evaluated the stability of nutritionally rich encapsulated spray-dried honey powders in terms of hygroscopicity, glass transition temperature, total phenolic content, antioxidant activity and ascorbic acid using maltodextrin, gum arabic, and whey protein concentrate as carriers during a storage period of 180 days using high-density polyethylene and aluminium laminated polyethylene as packaging materials at 25°C (room temperature) and 35°C (accelerated temperature). The results revealed that temperature caused a negative influence on the glass transition temperature and stability of ascorbic acid. The kinetics of ascorbic acid degradation followed a first-order reaction with a reaction rate constant dependent on temperature and packaging material. Honey powder developed with whey protein concentrate as carrier agent and stored in aluminium laminated polyethylene pouches at 35°C possessed the highest antioxidant activity and ascorbic acid due to the presence of phenolic compounds in honey, aonla (Emblica officinalis. Gaertn), and basil (Ocimum sanctum) extract. The honey powders stored in aluminium laminated polyethylene pouches showed comparatively better antioxidant properties (total phenolic content, ascorbic acid, and antioxidant activity) and minimum hygroscopicity than the powders stored in high-density polyethylene at both the storage temperatures.     

Biochemical,microbiological and sensory changes in shrimp (Panaeus aztecus) dipped in different solutions using face‐centred central composite design

Biochemical, microbiological and sensory changes during shelf‐life at ?1 °C were determined in shrimp (Panaeus aztecus) previously dipped in ascorbic acid, citric acid, potassium sorbate and 4‐hexyl resorcinol solutions using face‐centred central composite design. Microbiological count, trimethylamine and hypoxantine production were measured. The lowest level of the total psychrotrophic bacteria, hypoxantine and trimethylamine were found in samples dipped in all containing chemicals solutions comparing to control treatment. Sensory studies showed that treatment A (ascorbic acid 4.50, citric acid 0.12, potassium sorbate 18.60 and 4‐hexyl resorcinol 0.25, all g L^?1) and B (ascorbic acid 4.37, citric acid 1.26, potassium sorbate 7.03 and 4‐hexyl resorcinol 0.25, all g L^?1) did not alter the typical sensory features of shrimp and were effective at delaying the bitter off‐flavour formation for 26 days. This study constitutes a promising alternative to extent shelf‐life of shrimp kept at ?1 °C without freezing.     

Vitamin C kinetic degradation of strawberry juice stored under non-isothermal conditions

Strawberries are a good source of nutritional compounds and may be considered among the fruit most rich in ascorbic acid (AA). Strawberry juice is easily damaged in transit due to temperature fluctuations that may significantly reduce shelf life. In this way, the use of “best before” and “use by” dates should be reconsidered in the light of temperature variability during transport or storage. Kinetic degradation of ascorbic acid and shelf life estimation of strawberry juice stored under non-isothermal conditions was performed using a Weibullian-logistic model. A kinetic order of 1.1 was estimated as the best value to fit AA degradation under isothermal conditions and may be considered as the value for this particular medium. Moreover, the Weibullian-logistic model well fitted AA degradation under non isothermal conditions and may be used to predict shelf life under different fluctuation temperature histories. On the basis of temperature profiles considered in this paper, a retention of 46.8% and 42.7%, respectively for experimental and predicted data after 15 days were measured. Furthermore, it was showed a significant decrease of shelf life (about 5 days) for samples exposed to fluctuation temperature in comparison whit samples kept at constant temperature.     

The fate of furfurals and other volatile markers during the baking process of a model cookie

This work investigates the generation and the evolution of some neoformed compounds formed during the baking of a model biscuit. Thank to their physicochemical properties of volatility and hydrophobicity, furfurylic compounds were followed by a double approach: the analysis of the volatile fraction extracted from food matrix and from the vapours released during the thermal process. 5-Hydroxymethylfurfural (HMF) was the main furfurylic compound formed, it followed an exponential kinetic in both the matrix and the vapours of baking biscuits. However, at the very final stage of baking a drop in HMF was observed in the cookie matrix whereas increasing amounts of HMF were still found in the vapours of baking. Moreover, some degradation products of HMF such as furaldehyde (F) and 2-methylfurfural (MF) were also detected. These observations support the hypothesis of a concomitant volatilization and degradation of HMF during the baking of the model cookie, under our experimental conditions.     

Antioxidant Action of Borage, Rosemary, Oregano, and Ascorbic Acid in Beef Patties Packaged in Modified Atmosphere

ABSTRACT: Beef patties containing either ascorbic acid, rosemary, oregano, or borage were evaluated for storage stability at 2 ± 1 °C, by measuring a* and H* values, surface metmyoglobin, TBARS, psychrotrophic bacteria counts, and sensory off‐odor and discoloration. All of the antioxidants (except ascorbic acid) reduced (p < 0.01) TBARS formation, which was totally inhibited by borage. Myoglobin oxidation and color fading were inhibited (p < 0.01) by rosemary, oregano, and borage. Microbial growth showed insignificant differences among treatments. Sensory results showed that rosemary, oregano, and borage extended beef patties' shelf life from 8 to 12 d, while rosemary plus ascorbic acid extended shelf life an additional 4‐d period.     

Extending Shelf Life of Fresh-cut Pears

The effects of various treatments were evaluated for extending shelf-life of fresh-sliced pears. Sliced Anjou pears had browning-free color for 30 d by dipping with 1.0% ascorbic acid and 1.0% calcium lactate, but texture was soft with juice leakage. The combination treatment of 0.01% 4-hexylresorcinol (4-HR), 0.5% ascorbic acid and 1.0% calcium lactate can provide 15 to 30 d shelf-life for Anjou, Bartlett, and Bosc pears when the pears are sliced at an average ripeness of 43, 49, and 38 Newton respectively, with 2 min dipping, partial vacuum packaging, and 2 to 5 °C storage. 4-HR residual content ranged from 1 to 7 ppm after 14 d storage. Panelists could detect a flavor difference between 0.01% 4-HR treated pears and controls.     

Effect of storage on the bioactive compounds and antioxidant activity of quince nectar

The changes of bioactive components and antioxidant activity of quince nectar were determined during 9 months of storage at 5, 20, 30 and 40 °C. The amount of total phenolics, flavonoids and antioxidant activity was significantly declined during storage at all temperatures. Loss of L‐ascorbic acid at 5, 20, 30 and 40 °C was 32.08%, 43.69%, 65.21% and 88.82%, respectively. L‐ascorbic acid degradation was in accordance with the first‐order reaction kinetics, and activation energy was found as 43.65 kJ mol^?1. After 9 months of storage, Hydroxymethylfurfural (HMF) contents of quince nectars were 15.01, 16.64, 21.69 and 57.89 mg kg^?1 at 5, 20, 30 and 40 °C, respectively. HMF accumulation fitted a zero‐order kinetic model, and activation energy was found as 88.30 kJ mol^?1. A significant correlation was found among L‐ascorbic acid, total phenolics, flavonoids and antioxidant activity.