Effect of sub‐freezing storage (−6, −9 and −12 °C) on quality and shelf life of beef

Based on the results of low field nuclear magnetic resonance (LF‐NMR) in our current study (the frozen state of ?6, ?9 and ?12 °C were nearly the same with extremely low free water content), ?6, ?9 and ?12 °C was designated as sub‐freezing temperatures. The effects of sub‐freezing storage compared with conventional chilling (4 °C), superchilling (?1 °C) and conventional freezing (?18 °C) on the quality and shelf life of beef were analysed. Results showed that the shelf life of beef is extended to 84 and 126 day at ?6 °C and ?9 °C, respectively. However, the TVB‐N values of the samples stored at ?12 °C and ?18 °C remained below 15 mg/100 g even on 168 day. Furthermore, shear force, colour, pH, thiobarbituric acid reactive substances (TBARS) and sensory properties were also measured. Consequently, the sub‐freezing storage has significantly extended the shelf life of beef compared to chilling and superchilling (P < 0.05). Moreover, no significant difference (P > 0.05) was found between the indicators for quality and shelf life of samples stored at ?12 and ?18 °C throughout 168 days.     

Effects of β‐cyclodextrin addition and farming type on vitamin C,antioxidant activity,carotenoids profile,and sensory analysis in pasteurised orange juices

The effects of organic farming, pasteurisation and addition of β‐cyclodextrin on the content of vitamin C, colour, carotenoids and antioxidant capacity of orange juices were studied. After pasteurisation at 98 °C (20 s) and subsequently storage along 145 days at room temperature (20–25 °C), the loss of vitamin C content was around 30%. The effects of the thermal process on carotenoid were clearly observed in lutein (loss of 16% for organic and traditional 8%) and especially β‐cryptoxanthin (loss of 30%). The colour changes were noticeable after the pasteurisation of orange juice and subsequent storage, with significant decreases being observed in lightness and the coordinate a*, while increases were found for coordinates b*, Hue* and chroma. The antioxidant capacity was 0.075 ± 0.01 and 0.053 ± 0.01 mMT mL^?1 for organic and conventional, respectively, with losses around 40% being found at the end of the storage period. The addition of β‐cyclodextrin caused no significant effects on the parameters under analysis. These data showed that strong thermal treatments, such as pasteurisation, adversely affect the nutritional and sensory quality of orange juices.     

Influence of a combined hot air and UV‐C treatment on quality parameters of fresh‐cut broccoli florets at 0 °C

Broccoli is a horticultural product with a high nutritional value that can be consumed fresh but also minimally processed. However, broccoli is highly perishable since it develops a senescence quickly that deteriorates commercial and nutritional quality of the product. In this work we analysed the effect of a combination of UV‐C and heat treatment on quality and senescence of fresh‐cut broccoli florets stored at 0 °C. Combined treatment delayed yellowing as evidenced by higher Hue values and lower chlorophyll degradation. The treatment diminished respiratory activity indicating higher tissue integrity. Treated samples showed higher phenolic content and antioxidant capacity. On day 21 of storage, treated samples had higher levels of total sugars, and total proteins. The results suggest that a combined treatment with heat and UV‐C may reduce senescence, tissue damage and helps to maintain a better quality of the product during storage at 0 °C.     

Extractability and thermal stability of frozen hake (Merluccius merluccius) fillets stored at −10 and −30 °C

The relationship between thermal stability changes and functionality loss was monitored in hake muscle fillets stored for 40 weeks at ?10 and ?30 °C. The evolution of changes in apparent viscosity, dimethylamine formation and extractability of muscle proteins in NaCl, sodium dodecyl sulphate (SDS) or SDS plus mercaptoethanol showed drastic differences as a function of temperature. At the higher storage temperature, both myosin heavy chain and collagen were the most severely unextracted in salt and SDS solutions, with actin becoming unextractable at the end of storage. Differential scanning calorimetry showed differences with storage time and temperature in both onset temperature and thermal denaturation enthalpy, mostly affecting the myosin transitions. Some protein denaturation occurred with little or no functionality loss. A considerably high fraction of hake muscle proteins remained in the native‐like condition even at the higher frozen storage temperature. In these conditions both apparent viscosity and myosin and actin extractability in NaCl were very low. © 2002 Society of Chemical Industry     

Comparison of changes occurring in rheological properties of gelled tissue and model sausage prepared from duck breast muscles stored at −2°C and −18°C

The changes of rheological parameters of gelled tissue and model sausage prepared from duck breast muscles stored at ?2°C and ?18°C were compared. The changes of conventional elasticity and flowability and the sum of reciprocal immediate elasticity modulus and reciprocal elasticity modulus of gelled tissue, and conventional plasticity and Newtonian viscosity of model sausage are comparable for both temperatures and are higher at ?2°C than ?18°C. At both temperatures the changes occurring in rheological parameters of model sausage can not be predicted according to the changes in rheological parameters of gelled muscle tissue.     

Development of Active Films From Pectin and Fruit Extracts: Light Protection,Antioxidant Capacity,and Compounds Stability

Pectin films containing fruit extracts were developed and tested in relation to ultraviolet light transmission, phytochemical contents, and antioxidant capacity during 90 d shelf life storage. Aqueous and alcoholic extracts from 5 different fruits (acerola, cashew apple, papaya, pequi, and strawberry) were obtained. Because the alcoholic extracts from acerola, cashew apple, and strawberry presented the highest phytochemical content and antioxidant capacity, they were incorporated into pectin films individually or as a mixture. Incorporation of these extracts into pectin films provided antioxidant capacity while retaining the physical properties. The pectin films containing fruit extract acted as adequate light barrier and prevented photooxidation. Among the prepared films, the pectin film containing acerola extract afforded the highest antioxidant capacity, with a half‐life of 99 d. Overall, the results revealed that incorporation of fruit extracts into pectin films potentially produces antioxidant films and coatings for different food applications.     

The origin of free fatty acids formed in frozen cape hake mince (Merluccius capensis,castelnau) during cold storage at −18°C

Hake mince was stored at ?18°C and samples were withdrawn at intervals during a 300-day period. The extracted lipids were examined for free fatty acid (FFA) and phosphorus (P) content. Total FFA contents were corrected for a phospholipid contribution and converted into genuine FFA contents. Using these genuine FFA contents and the knowledge that the loss of one mole of lipid-P produces two moles of FFA made it possible to calculate the separate contribution of the phospholipids and the neutral lipids to the FFA formed on storage. It was found that FFA originated from both phospholipids and neutral lipids and after an initial rapid surge of FFA formation from both sources the rates declined and became virtually constant. The results for the Cape hake are compared with literature data of the Atlantic cod and the Baltic herring.     

Peroxidase,catalase and palmitoyl-CoA hydrolase activity in blanched carrot cubes after storage at −20°C

The effect of storage at ? 20°C was studied on carrot cubes which had been blanched at 50°, 60°, 70° and 80°C for 2, 5, 10 and 20 min. A sample of unblanched carrot cube was used as reference. Results from sensory methods were compared with the activity of the three enzymes, palmitoyl-CoA hydrolase, catalase and peroxidase. Good quality retention was obtained when palmitoyl-CoA hydrolase was no longer present, while activity of catalase (9%) and peroxidase (6%) remained.     

Cell Wall Changes and Partial Prevention of Fruit Softening in Prestorage Heat Treated ‘Anna’ Apples

Prestorage heat treatment (38°C for 4 days) retarded the softening of ‘Anna’ apple fruits during 0°C storage. Fruit softening of unheated apples during storage was accompanied by changes in pectic substances: a decrease in uronic acid content in the carbonate-soluble fraction and an increase in the water-soluble fraction. Heat treatment partially inhibited the degradation of uronic acids in the cell wall. The degree of pectin methylation in both heated and non-heated fruit decreased during storage. In heat treated apple fruit the content of galactose and arabinose in the cell wall decreased during storage; in non-heated fruit only galactose decreased. We suggest that the inhibition of solubilisation of the carbonate soluble pectin fraction is one of the main factors contributing to the firmness retention caused by heat treatment. The loss of both arabinose and galactose in heat treated fruits may also play an as yet undefined role in the effect of heat treatment on fruit softening.     

Effects of different nitric oxide application on quality of kiwifruit during 20 °C storage

The effects of fumigating with 0, 10, 20, 30 μL L^?1 nitric oxide (NO) gas and dipping in 0.5, 1.0 and 2.0 μmol L^?1 NO aqueous solution on quality of kiwifruit (Actinidia Chinensis Planch cv Xuxiang) during storage at 20 °C were evaluated. It was found that fumigating with 20 μL L^?1 NO gas and dipping in 1.0 μmol L^?1 NO aqueous solution delayed firmness lost and increased SSC/TA ratios of kiwifruits. In comparison with the kiwifruits fumigated with 20 μL L^?1 NO, the kiwifruits dipped in 1.0 μmol L^?1 NO solution had slower ethylene production, lower contents of soluble solids and malondialdehyde (MDA), higher contents of vitamin C and E, but no significant difference existed in chlorophyll contents. The results suggested that dipping kiwifruits in 1.0 μmol L^?1 NO aqueous solution was more effective in maintaining kiwifruits quality during 20 °C storage.     

Stability of vitamin C in fruits and fruit blends

The levels of the two biologically active forms of vitamin C, ascorbic acid (AA) and dehydroascorbic acid (DHAA), were determined in individual fruits, in fruit blends and in model systems over a 3-h incubation period at room temperature. There was essentially no reduction in the AA content in the orange juice sample and in the model solution of analytical ^l-ascorbic acid. A rapid decrease in the AA content was observed in the banana, apple and guava samples and in blends consisting of orange juice-banana-apple or L -ascorbic acid-banana-apple blends. However, the reduction in AA was concomitant with a quantitative increase in DHAA content.     

The influence of organic/integrated production on the content of phenolic compounds in apple leaves and fruits in four different varieties over a 2‐year period

BACKGROUND: Phenolics in fruit may be influenced by the fruit type, cultivation conditions of a plant, climatic conditions, growing season, storage conditions, and industrial processing. The aim of this study was to compare single phenolic compounds, total phenolics and antioxidant capacity of four varieties of apple grown under organic and integrated conditions over a 2‐year period. RESULTS: Several different phenolic compounds belonging to the groups of hydroxycinnamic acids, flavanols, dihydrochalcones, flavonols and anthocyanins were quantified. The levels of all analysed groups of phenolics were higher (not always significantly) in the organically grown apple leaves and fruit than in the leaves or apples from integrated production. Leaves from organic trees had 10–20% higher content levels of total phenols than the leaves from trees in the integrated growing system. In both years, organic production affected the increase in the antioxidant activity of apple peel. Organic apples have higher total phenolic content than the integrated grown ones. CONCLUSION: Cultivation type had an important influence on the polyphenolic level and antioxidant capacity of the apple fruits and leaves. Apples from organic production showed a higher content of hydroxycinnamic acids, flavanols, dihydrochalcones, quercetins and total phenolics than apples from integrated cultivation. Copyright © 2010 Society of Chemical Industry     

Effect of environmental factors [air and UV-C irradiation] on some fresh fruit juices

The present study was carried out to evaluate the effect of environmental factors (air and UV-C irradiation) on various common fruits juices (lemon, orange, papaya and grape). Total phenolics, total ascorbic acid (AA) content and antioxidant capability were determined in atmospheric air oxidation on fresh fruit juices, and the effect of UV-C irradiation on AA was investigated in both fresh fruit juices and commercial AA using RP-HPLC. The total phenolics content was found to be 92.46?±?1.5, 41.53?±?2.1, 138.56?±?2.3 and 110.54?±?3.9?mg/100?ml of lemon, orange, papaya and grape juices, respectively. DPPH radical–scavenging activity of the fresh juices was 94.53?±?3.1, 82.36?±?2.2, 94.65?±?3.5 and 90.74?±?2.6 percentage, whereas the 1-day-old fruit juices showed reduced scavenging activity when compared to fresh juices. Total phenolic (TP) and DPPH-scavenging activity were significantly decreased in the mean at P?<?0.05 level. Ascorbic acid (vitamin C) content of fresh fruit juices was determined through RP-HPLC; fruit juices that were kept in open container for 24 hrs and that were treated with UV irradiation have shown a decrease in AA content, when compared with control fresh juice samples. AA degradation increased with high significant differences at P?<?0.001 level, with the increase in oxidation time in atmospheric air and UV-C radiation.     

Effects of temperature on the chemical composition and antioxidant activity of three strawberry cultivars

Three strawberry cultivars (Dover, Campineiro, and Oso Grande), grown in the same commercial plantation, were harvested at the ripe stage and stored at 6, 16 and 25 °C, for 6 days. During this period, chemical composition and antioxidant activity were evaluated. Results showed an increase in total soluble sugars, anthocyanin and vitamin C contents, indicating that a new biosynthesis had taken place during storage. Low temperature negatively affected anthocyanin and vitamin C accumulation, and positively affected soluble sugars, while flavonols, ellagic acid and total phenolic contents remained almost the same or even decreased at all temperatures. Despite differences in anthocyanin content between varieties and its increase during storage (higher with increasing temperature), there was no difference in the antioxidant activity between cultivars, which decreased after harvesting, independently of the temperature of storage. Variations in the proportion dehydroascorbic acid/ascorbic acid (DHA/AA) showed that there were differences between cultivars concerning adaptation of the fruit to low temperatures. The data obtained here indicate that cold storage is an effective way to maintain strawberry quality, but a compromise between sensorial and nutritional values can be achieved at 16 °C, for all the cultivars.     

Changes in Quality and Nutritional Parameters During Refrigerated Storage of an Orange Juice–Milk Beverage Treated by Equivalent Thermal and Non-thermal Processes for Mild Pasteurization

The effects of high-pressure (HP) treatment (400?MPa at 42 °C for 5 min) and pulsed electric field (PEF) processing (25 kV/cm at 57 °C for 280 μs) on ascorbic acid, total carotenoids, total phenolic compounds and total antioxidant capacity (TEAC and ORAC) of an orange juice–milk (OJ-M) beverage along the storage time at 4 °C were compared with a conventional heat preservation technology used in industry (90 °C for 15 s). During storage, ascorbic acid, total carotenoids and antioxidant capacity (TEAC) depleted with time regardless of the treatment applied. Instead, total phenolic content and antioxidant capacity measured by the ORAC method increased at the end of the storage. Non-thermal-treated beverage had less non-enzymatic browning than the thermally pasteurized one. There were no significant variations in the hidroxymethylfurfural (HMF) content of the HP- and PEF-treated OJ-M, whilst a significant increase was obtained after thermal treatment. During refrigerated storage, HMF was always below the maximum values established. The HP treatments reduced the L* value of the treated beverages immediately after processing and during refrigerated storage and induced an increase in total colour differences of beverages treated by HP compared with PEF and thermally processed orange juice–milk. Hence, alternative methods such as HP and PEF may give new opportunities to develop orange juice–milk with an equivalent shelf life to that of thermally treated orange juice mixed with milk in terms of microbial, physicochemical and nutritional characteristics.     

Characterisation of ‘Starking’ apple polyphenoloxidase

Experiments were performed to optimise the extraction conditions of ‘Starking’ apple fruit polyphenoloxidase (PPO), to evaluate the affinity and specificity towards several substrates and to study the stability of enzyme extracts from apple samples stored under different conditions. Sodium phosphate buffer (0·2 M , pH 6·5) plus 0·25% Triton X₁₀₀ and 1% or 2% PVPP was found to be the most efficient extraction medium. Chlorogenic acid, dopamine and 4-methylcatechol showed similar specificity towards PPO, and chlorogenic acid was found to be the best substrate for the enzyme. Enzyme extracts from frozen cut apple stored at −4°C, and extracts from lyophilised apple samples stored at 4°C were more stable than extracts obtained from fresh-cut or acetone powder samples. © 1998 SCI.     

Effect of Processing and Storage on The Antioxidant Activity of Frozen and Pasteurized Shadblow Serviceberry (Amelanchier canadensis)

Serviceberry fruits were pasteurised in glass jars at two temperatures, 85 and 100°C, while another batch was packed in polyethylene bags and frozen at a temperature of ?20 ± °C. Processed fruits were stored for 10 months: frozen fruit at ?20 ± 1°C; and pasteurised fruit at room temperature without access to light. Refrigerated storage and pasteurization lowered the DPPH antioxidant activity of serviceberry fruit. In the former, the change was not great, whilst pasteurisation caused an approximately twofold increase in EC50. On the basis of total anthocyanin content and total polyphenolic content measurements, it would appear that the antioxidant properties of serviceberry were affected mainly by anthocyanins. Pasteurising at 100°C allowed slightly better preservation of these compounds during long-term storage.     

Antioxidant properties and shelf‐life extension of fresh‐cut tomatoes stored at different temperatures

BACKGROUND: The feasibility of using modified atmosphere packaging (5 kPa O₂ + 5 kPa CO₂) to maintain the antioxidant properties of fresh‐cut tomatoes during shelf‐life was assessed through storage at different temperatures (5, 10, 15 and 20 °C). Health‐related compounds, antioxidant capacity, microbiological counts, physicochemical parameters and in‐package atmosphere of tomato slices were determined. RESULTS: Initial lycopene, vitamin C and phenolic contents and physicochemical parameters of tomato slices were well maintained for 14 days at 5 °C. Lycopene and total phenolic contents were enhanced over time in tomato slices stored at 15 and 20 °C. However, this increase in antioxidant compounds of fresh‐cut tomatoes during storage may be associated with excessive amounts of CO₂ (R² = 0.5679–0.7328) in the packages due to microbial growth. Although keeping tomato slices at temperatures above 10 °C increased their antioxidant content, the shelf‐life of the product was reduced by up 4 days. CONCLUSIONS: A storage temperature of 5 °C is appropriate for maintaining the microbiological shelf‐life of fresh‐cut tomatoes for up to 14 days and also allows the antioxidant properties of tomato slices to be retained over this period, thus reducing wounding stress and deteriorative changes. Copyright © 2008 Society of Chemical Industry     

The oxidative stability of lard at −20°C: Evidence for a synergistic prooxidant effect of copper and curing salts

In connection with an interest in the problem of rancidity development in cold-stored cured meat products (particularly bacon), the effect of certain trace components and permitted food additives on the oxidative stability of model systems containing lard was examined. Lard, to which additions of various single additives or combination of additives had been made, was stored for periods of up to 16 weeks at ?20°C. Samples were removed during this time to assess the extent of their oxidation by chemical analysis (peroxide value determination) and sensory evaluation (odour). The additives studied included water, sodium chloride, sodium nitrate, sodium nitrite and copper (as palmitate, acetate and sulphate). It was observed that there was progressive oxidative deterioration of the lard with noticeable rancidity developing after 8 to 16 weeks' storage at ?20°C when water, sodium chloride, sodium nitrate, sodium nitrite and copper were present in combination.     

Utilisation Potential of Feijoa Fruit Wastes as Ingredients for Functional Foods

Feijoa fruits have high antioxidant activity as they contain significant concentrations of polyphenols (PPs), carotenoids and vitamins. This study evaluates the colour, pH, total soluble solids (TSS), pectin fibre content, total extractable PP content (TEPC) and total antioxidant activity of the extracts generated from the fruit wastes (primarily skin and some flesh) remaining after feijoa flesh consumption. Extractions were conducted at room temperature and 50 °C using accelerated solvent extraction technology and different extraction media [water, acidified water (containing citric acid, pH?3.5), and 30, 50 and 80 % (v/v) aqueous ethanol solutions]. Results show that the composition and properties of the extracts depend on the extraction media and, to a lesser extent, on the extraction temperature. The 80 % ethanolic extract was bright green in colour. The water and acidified water extracts showed more browning than the ethanolic extracts, suggesting possible detrimental sensory impacts for food applications. The TSS decreased in the order of 80, 50 and 30 % ethanolic and water extracts. The 50 % ethanolic extract had the highest TEPC and antioxidant activity at both extraction temperatures, which was supported by high performance liquid chromatography analyses. The extracts produced with solutions containing less ethanol, especially water extracts, had higher pectin contents. The UA content of the extract produced using water alone was the highest (5.56 % as GalA) at 20 °C, whilst that produced using 30 % ethanol solution was the highest (3.90 % as GalA) at 50 °C. Higher extraction temperature (50 °C) resulted in lower pectin contents. These results demonstrate the potential of feijoa waste extracts, especially 50 and 80 % ethanolic extracts, as ingredients for functional food applications.