Postharvest structural changes of Hayward kiwifruit by means of magnetic resonance imaging spectroscopy

In the present study magnetic resonance imaging (MRI) was used to evaluate the effect of storage conditions, 0 °C and 90% relative humidity (RH) or 20 °C and 70% RH, on minimal structural changes of kiwi tissue. Storage time was 35 days at 20 °C and 65 days at 0 °C including shelf life. Ethylene and respiration were followed during the experiment as well as commercial quality parameters such as sugars and firmness. MRI images weighted for proton density (ρ) and transverse relaxation times (T₂), were recorded after 10, 20, 35, 55 and 65 days. A decrease of the diameter was clearly visible in samples stored at 20 °C after 3 weeks and a coarse contour of the pericarp appeared after 40 days. Accumulation of water in the pericarp was found, suggesting a migration towards the outer regions occurs and that the fruit water loss due to evapo-transpiration is slower than the migration process. Samples stored at 0 °C showed no relevant changes in dimension and structural features for the whole period considered except after removal to shelf life. The observed variations of the internal morphology were correlated with the transverse relaxation times of defined areas and with softening of fruits. Measured T₂ profiles showed double-exponential decays, a fast- and a slow-relaxing component, indicating the existence of two different types of water molecules within cellular tissues: strongly and weakly bound, respectively. The relation among MRI data, ethylene and softening is discussed.     

Different postharvest strategies to preserve broccoli quality during storage and shelf life: Controlled atmosphere and 1-MCP

Broccoli (Brassica oleracea var. italica) is a vegetable that requires the application of postharvest techniques to extend its marketability. Controlled atmosphere and 1-MCP treatments are most used to extend the shelf life of broccoli and reduce post-harvest deterioration. The aim of this study was to evaluate the visual, physicochemical and functional changes of broccoli head samples stored at 1–2 °C and 85–90% relative humidity (RH) in air (Control samples), under controlled atmospheres (10% O₂ and 5% CO₂) (CA samples) and treated with 1-MCP (0.6 μL/L). After storage all samples were maintained at 20 °C for 2 and 4 days, in order to assess their shelf life. The most suitable postharvest treatment to extend broccoli quality during storage and shelf life, in terms of maintaining the visual quality and reducing loss of health-promoting compounds, was achieved by storage under controlled atmosphere conditions. The use of 1-MCP reduced the loss of green colour and chlorophyll pigments, but only during cold storage not during shelf life at 20 °C.     

Oxidation of linoleic acid as a marker for shelf life of corn flour

The objective of this study was to measure the oxidation of linoleic acid of nixtamalised corn masa (NCM) during an accelerated shelf life study at high temperature (45–85 °C), and 0.45 a_w for 180 days. Linoleic acid (LA) was present at 55.1%, followed by oleic acid (26.9%), as measured by gas chromatography. The propagation of lipid oxidation, measured by anisidine value, reached its peak 2–5 days after the peroxide value had passed over its maximum value. At this time, flour showed at least a 10% reduction of LA; but, at the end of storage only 10% of LA remained. The autocatalytic oxidation of linoleic acid in NCM was temperature-dependent, with Q₁₀ = 1.4. The index of quality loss for corn flour stored at 55 °C was 0.48% per day; under these conditions 50% of its quality decreased in only 104 days. Mathematical modelling estimates a shelf life of 84 days for corn masa (<6 meq/kg peroxide) stored at 25 °C.     

Evaluation of lipid oxidation in spaghetti pasta enriched with long chain n−3 polyunsaturated fatty acids under different storage conditions

This study investigated lipid oxidation in spaghetti enriched in long chain n−3 polyunsaturated fatty acids (LC n−3 PUFA) by the addition to semolina of an integrator containing eicosapentaenoic acid and docosahexaenoic acid. Two oxidative parameters were evaluated: peroxide value (PV), to assess primary oxidation and oxidised fatty acids to quantify secondary oxidation products. Functional spaghetti had a shelf life comparable to control pasta. LC n−3 PUFA were not significantly implicated in the onset of oxidation in spaghetti stored under daylight and accelerated oxidation in a laboratory heater. Storage decidedly affected shelf life: PV in functional spaghetti increased from 7.1 to 43.4 meq O₂/kg of fat under light exposure over 12 months, and from 7.1 to 16.2 meq O₂/kg under accelerated ageing at 55 °C for 27 days, reproducing about 18 months at room temperature. Oxidised fatty acids increased in fortified spaghetti from 4.8 to 13.8 g/100 g of fat under light exposure over 12 months and from 4.8 to 7.8 g/100 g of fat at 55 °C in 27 days. The high sensitivity of spectrophotometric and chromatographic analytical methods permitted the evaluation of primary and secondary oxidative derivatives in small amounts of fat.     

Shelf life prediction of packaged cassava-flour-based baked product by using empirical models and activation energy for water vapor permeability of polyolefin films

Moisture sorption kinetics and isotherms of cassava-flour-based baked product were investigated. Empirical models were tested to fit the experimental data. Textural changes of the product were investigated. In addition, activation energies (E_p) for water vapor permeability (WVP) of polyolefin films were determined. Finally, the product was packaged in low-density polyethylene (LDPE) or oriented polypropylene (OPP) pouches, and stored at 30 ± 1 °C and 50 ± 2% RH to simulate actual storage conditions and to determine shelf life. This actual shelf life was compared to the predicted shelf life by using empirical models and E_p for WVP. Moisture sorption kinetics was more rapid during the initial stage, while a lesser amount of moisture was adsorbed as adsorption time increased. The higher the relative humidity used, the more pronounced the effect. The sigmoidal moisture sorption isotherms of this product can be classified as type II. The GAB model was found to be the best-fit model for this product. Once the product hardness or work reached the maximum and began to reduce at moisture content (MC) ≈6%, the product texture began to be detected as becoming slightly soft. This implies that hardness and work at the maximum level could be used to identify the critical MC which causes a loss of crispness to an unacceptable degree. The predicted shelf lives – estimated by employing E_p for WVP of LDPE and OPP, and the GAB model – were close to the actual shelf lives. Therefore, the estimation by empirical models and activation energy was found to be applicable for rapid and accurate shelf life prediction.     

Freshness decay and shelf life predictive modelling of European sea bass (Dicentrarchus labrax) applying chemical methods and electronic nose

European sea bass (Dicentrarchus labrax) is one of the finfish species preferred by the consumer, who requires fish freshness to be maintained during distribution and retail. For this reason, the purposes of this study were to define: the shelf life at three storage temperatures (−0.5, 4.8 and 16.5 °C) by applying both chemical (TVB and TBA assays) and olfactometric (e-nose) method; the actual time-temperature exposure conditions during marketing; the prediction of remaining shelf life in the commercial chain, on the basis of time-temperature history data and on appropriate integration routine. Shelf life study revealed the efficacy of chemical markers and electronic nose in describing the freshness decay and in defining a freshness threshold. Freshness of sea bass was kept for about 8 days for fish preserved in melting ice (−0.5 °C), 4 days at 4.8 °C and about 1 day at 16.5 °C. When fresh European sea bass was purchased, 9 out of 10 times the remaining shelf life was more than 55% at an average temperature of 1.19 °C. Therefore, the freshness of fish can be assured for 3-4 days in commercialization. A joint effort (sales point management and consumer advertising) could reduce the exposure temperature by 1-2 °C and justify an extension of the shelf life to 2-3 days after purchase.     

Influence of high pressure homogenization and pulp reduction on residual pectinmethylesterase activity,cloud stability and acceptability of Lane Late orange juice: A study to obtain high quality orange juice with extended shelf life

Lane Late orange juice with extended shelf life (3 months at 3 °C) was obtained by high pressure homogenization (HPH) at 150 MPa at 68 °C for 15 s. Residual pectinmethylesterase (PME) inactivation level achieved was 75% but its cloudiness was maintained during storage and its acceptability undistinguishable from that of fresh juice during the assayed period. Juices with entire and reduced (50% and 25%) pulp contents were also homogenized at 150 MPa at different temperatures (63 °C and 58 °C for 15 s) to establish an appropriate shelf life of orange juices according to a desired level of cloudiness. Results showed how cloud stability of pulp reduced samples, even with a residual PME inactivation level above 90%, was not satisfactory (as in the case of entire juices homogenized out of 68 °C). The proposed methodology can easily be implanted by citrus industry to obtain high quality chilled orange juices with prolonged shelf life.     

Headspace volatile composition and oxidative storage stability of pressed marama bean (Tylosema esculentum) oil

Marama bean (Tylosema esculentum) is an underutilised legume indigenous to the Kalahari Desert region of southern Africa. The bean has high lipid content and hence is a potential source for production of edible oil. The headspace volatile composition of freshly pressed marama bean oil was explored and the oil was further studied during 7 months of storage under different light and temperature conditions. The oxidative stability of the oil was examined by measuring peroxide value, vitamin E content and FT-IR spectra. Additionally, the headspace volatile composition of the oil was investigated during storage by use of dynamic headspace GC–MS. The results showed that marama oil is highly stable and has good natural antioxidant properties; enzymatic lipid oxidation does not take place in marama oil. Light has a greater effect on the lipid oxidation than has temperature, and hence marama oil should preferably be stored in darkness and rather at 25 °C than 35 °C. Under these conditions, the marama oil has a shelf life of at least 7 months.     

Viability of total phenol index value as quality marker of sparkling wines, “cavas”

To evaluate the viability of the A280 value for monitoring the development of cava sparkling wine during its ageing in contact with lees and its commercial shelf life, an accelerated test was applied to four types of sparkling wines obtained at industrial scale. All cava types were stored under oxygen and carbon dioxide conditions at 37 °C for 13 weeks. During the accelerated test, a positive relationship between absorbance at 280 nm (A280) and time was observed, while the main phenolic compounds decreased even under nonoxidative conditions. The increase in the phenol index value corresponded (p < 0.01) to an increase in a colourless compound. Both increases occurred mainly under nonoxidative conditions. This compound is a tentatively identified polyhydroxylate structure with a λ_max 284 nm and an accurate mass of 178.0398, which corresponds to the molecular formula, C₆H₁₀O₆. The present study found that sugars are the origin of this compound and play an important role in A280 increase under reductive conditions. The value of A280 could be a simple marker for monitoring the quality of the evolution of sparkling wine during its ageing in contact with lees and its commercial shelf life.     

Engineering packaging design accounting for transpiration rate: Model development and validation with strawberries

Integrative mathematical modelling for Modified Atmosphere Packaging (MAP) has been used to determine the gas composition inside a package, but can also be used to determine the packaging needs of fresh produce in terms of permeability to gases and water vapour. Transpiration rate (TR) is an important physiological process that influences relative humidity (RH) and condensation inside the package, and ultimately quality and shelf life. Strawberries are an extremely valuable crop, but they are susceptible to grey mould rot, fungal decay, moisture loss and condensation. Quantification of strawberry transpiration rate TR would be required to estimate the packaging material water vapour transmission rate (WVTR) and therefore optimise engineering packaging design. This study investigated (i) the impact of temperature and RH on strawberry TR, (ii) developed a predictive model for quantifying TR, (iii) integrated transpiration rate model into the engineering packaging design and quantified the target WVTR for packaging of strawberry and (iv) validated packaging design by comparison to commercial packaging. Experiments were conducted following an experimental design, considering two factors at three levels (3²), i.e. temperature (5, 10 and 15 °C) and RH (76%, 86% and 96%); TR was recorded during 5 days of storage. The results showed that both RH and temperature had a significant effect on TR. In a given temperature and RH range of study, it varied from 0.24 to 1.16 g/kg h. Mathematical model developed considering the effect of temperature and RH, was further validated at 12 °C and 76% RH, showing very good predictability (R² > 0.997). The TR model was found to be useful for describing the strawberry packaging requisites and for optimal engineering packaging design for strawberry. The target WVTR for achieving optimal RH of 90% at 5 °C was found to be 162 g/m² day. Packaging design validation showed that the package designed considering both gas and water vapour requisites of strawberry yielded favourable results for maintaining quality and shelf life of product.     

Green tea – A potential preservative for extending the shelf life of fresh mutton at ambient temperature (25 ± 2 °C)

This investigation was taken up to evaluate the feasibility of using green tea (GT) to extend the shelf life of fresh mutton, at ambient storage conditions (25 ± 2 °C and 85 ± 5% RH). The ethanolic extract of GT (GTE) was found to significantly inhibit (P < 0.01) spoilage microflora, including certain pathogens of acidulant treated mutton (pH 3.8) for up to 4 days. Application of GTE did not cause any deleterious change in sensorial and physical quality and the mutton was acceptable for up to 4 days. While the control samples showed initial signs of spoilage between 20 and 24 h and registered an increase in free fatty acids (FFA) from 1.24 g to 4.1 g/100 g lipid and biogenic amine index (BAI) from 0.27 mg to 4.63 mg/100 g mutton, at the end of two days of storage, the GTE treated sample showed FFA levels of 1.5 g/100 g lipid and BAI of 0.25 mg/100 g mutton at the end of the 4 days. GTE treatment could be effectively used to extend the shelf life of fresh mutton for up to 4 days in Indian climatic conditions, since it significantly (P < 0.01) inhibits the formation of these lipolytic and proteolytic degradation products, which are responsible for sensorial spoilage.     

Sorption isotherms and thermodynamics of water sorption of ready-to-use Basundi mix

Basundi mix representing powdered Basundi (an Indian traditional milk product somewhat similar to sweetened condensed milk) is a convenience product developed for enhanced shelf life at ambient temperature. Water sorption isotherms were obtained for this ready-to-use mix over the temperature range of 5-45 °C. There was definite inversion of the temperature effect at high water activity (>0.7). GAB model gave excellent agreement between experimental and predicted values. Other properties of sorbed water viz., monolayer water, number of adsorbed monolayers, density and amount of bound water and surface area of adsorption were also obtained. The net isosteric heat of sorption had strong dependence on moisture content. The enthalpy-entropy compensation suggested that the sorption mechanism involved is enthalpy driven over the entire range of moisture content studied.     

Shelf life of pork from five different quality classes

A total of 117 loins were selected on the cutting line at 24 h post-mortem to study the long term shelf life (35 days, 4 °C) of vacuum packaged pork from five different quality classes (PSE: pale, soft, exudative; PFN: pale, firm, non-exudative; RSE: red, soft, exudative; RFN: red, firm, non-exudative; and DFD: dark, firm, dry). The microbial load at 0 d was not significantly different (P > 0.05) among the pork quality classes, indicating that the initial microflora was influenced by the dressing conditions at the plant, not by the meat quality class. But after 35 d of storage, total aerobic mesophilic and presumptive lactic acid bacteria counts were higher (P < 0.05) in DFD pork due to its higher ultimate pH. RSE was the second quality class most susceptible to spoilage, whereas PFN, RFN and PSE pork had similar microbial loads. Further research is needed to elucidate the causes of the shorter shelf life in RSE pork.     

Dietary citrus pulp reduces lipid oxidation in lamb meat

This study investigated the effect of replacing cereal concentrates with high levels of dried citrus pulp in the diet on lamb meat oxidative stability. Over 56 days, lambs were fed a barley-based concentrate (Control) or concentrates in which 24% and 35% dried citrus pulp were included to partially replace barley (Citrus 24% and Citrus 35%, respectively). Meat was aged under vacuum for 4 days and subsequently stored aerobically at 4 °C. The Control diet increased the redness, yellowness and saturation of meat after blooming (P < 0.01). Regardless of the level of supplementation, dietary dried citrus pulp strongly reduced meat lipid oxidation over 6 days of aerobic storage (P < 0.001), while colour parameters did not change noticeably over storage and their variation rate was not affected by the diet. In conclusion, replacing cereals with dried citrus pulp in concentrate-based diets might represent a feasible strategy to naturally improve meat oxidative stability and to promote the exploitation of this by-product.     

Nutritional characterization and changes in quality of Salicornia bigelovii Torr. during storage

Salicornia bigelovii Torr. (sea-beans or drift seeds in English, sea-asparagus in Chinese) is an oil-seed plant tolerant to seawater irrigation and perishable with a shelf life of only about 6 days at ambient temperature (25 °C). To provide a potential food supplement, nutritional value of S. bigelovii were determined together with its postharvest quality as affected by storage temperatures (0 °C, 2 °C, 8 °C and 25 °C). Nutritional analyses showed that S. bigelovii contained high vitamins and minerals, which made it an ideal nutritional and diet supplement. Storing S. bigelovii at low temperatures could be a practical technique to extend storage life by reducing the quality degradation. After conducing sensory evaluations and determining ascorbic acid and chlorophyll contents, the optimal temperature for storing S. bigelovii was around 2 °C. This research will help to develop technically effective and energy efficient methods for prolonging the shelf life of S. bigelovii.     

Effect of freezing on the physicochemical, textural and sensorial characteristics of salmon (Salmo salar) smoked with a liquid smoke flavouring

This study reports the effect of different refrigeration/freezing treatments on the physicochemical, textural and sensorial properties of farmed Atlantic salmon (Salmo salar) treated with a commercial liquid smoke flavouring. Observations were made on three groups of fillets - group RFS: salted, smoked and stored at 4 °C; group BFS: frozen at −25 °C for 24 h, thawed, salted, smoked and stored at 4 °C; and group AFS: salted, smoked and frozen at −25 °C for 24 h and stored at −18 °C - over a period of 45 days. Scores (on a scale of 1-9) were provided for different sensorial attributes by a panel of 10 trained tasters. Sixty percent of the panellists consistently preferred the AFS fillets. The maximum shelf life associated with each treatment was defined as the last sampling day on which a mean score of ≤5 was awarded for the fillet sensorial attributes by ≥50% of the panellists. Freezing the salmon for 24 h before smoking (BFS) did not increase its shelf life (30 days) over that of refrigerated smoked salmon (RFS). In addition, the former treatment had a negative effect on the adhesiveness, cohesiveness, smoke odour intensity and colour intensity of the flesh. However, maintaining the fish frozen at −18 °C (AFS) increased its shelf life (>45 days) and invested the flesh with greater firmness, cohesiveness and colour intensity.     

Quality and shelf life evaluation of pork nuggets incorporated with fermented bamboo shoot (Bambusa polymorpha) mince

Pork nuggets were processed by incorporating fermented bamboo shoot mince and their physico-chemical, microbiological and sensory characteristics were evaluated during 35 day storage at refrigeration temperature (4 ± 1 °C). Addition of fermented bamboo shoot significantly affects the pH, moisture, protein, fat, fiber, instrumental color values and texture profiles of nuggets, especially at 6% and 8% addition levels. Nuggets with 6% and 8% FBSM had significantly lower TBARS values at the end of the storage period (i.e. 0.39 and 0.33 mg malonaldehyde/kg respectively) compared to the control (0.84 mg malonaldehyde/kg). Bamboo shoot addition significantly improved the microbial and sensory qualities of the pork nuggets. Incorporation of fermented bamboo shoot at 8% level increased the shelf life of pork nuggets by at least two weeks i.e. from 21 days to 35 days at 4 ± 1 °C compared to the control.     

Dietary citrus pulp improves protein stability in lamb meat stored under aerobic conditions

The antioxidant effects of dried citrus pulp on proteins in lamb meat, when used as a replacement of concentrate in the feed, was studied using meat from 26 male Comisana lambs. The lambs of age 90 days had been grouped randomly to receive one of the three dietary treatments: (1) commercial concentrate with 60% barley (Control, n = 8), (2) concentrate with 35% barley and 24% citrus pulp (Cp24, n = 9), or (3) concentrate with 23% barley and 35% citrus pulp (Cp35, n = 9). Slices from the longissimus thoracis et lomborum muscle were packed aerobically and stored for up to 6 days at 4°C in the dark. The citrus pulp groups, Cp24 and Cp35, significantly decreased protein radicals and carbonyls, and preserved more thiols within six days of storage compared to the Control group. The citrus pulp groups significantly slowed down the rate of protein oxidation, indicating that dietary citrus pulp reduced oxidative changes in meat proteins.     

Comparative shelf life study of blackberry fruit in bio-based and petroleum-based containers under retail storage conditions

The shelf life of blackberries is relatively short, 2–3 days at 0 °C. Different marketing strategies like packaging can be used to retain blackberry quality during postharvest. This study compares the blackberry retail shelf life performance of different packaging materials, bio-based versus petroleum-based using the same packaging design. ‘Cancaska’ and ‘Chester’ blackberries were packaged in snap-fit closed packages made from oriented poly(lactic acid), OPLA, and oriented poly(styrene), OPS, and stored at 3 °C and 85% RH for three weeks. Both cultivars exhibited an increase in pH, weight loss, SSC to TA ratio, and fungal count, and a reduction in firmness, anthocyanin content, TA, and SSC during storage. The changes in TA, SSC, SSC to TA ratio, and weight loss significantly depended on the packaging material while no such effect was observed on firmness, anthocyanin content, pH and fungal growth. Both cultivars demonstrated better quality in the OPS container with less weight loss, and decrease in SSC and TA. Blackberries in both OPS and OPLA containers met the “US standard No 1” grade for commercialisation for more than 12 days at 3 °C.     

Analysis of vitamins A,E and C,iron and selenium contents in infant milk-based powdered formula during full shelf-life

The stability of vitamins A, E and C, and the iron and selenium content were determined in two types of long chain-polyunsaturated fatty acid (LC-PUFA) supplemented milk-based powdered infant formulas (IF), during an 18-month storage period at 25 and 40 °C. The first type (IF-A) was supplemented with vitamin A as retinol acetate. The second type (IF-B) was supplemented with vitamin A as retinol palmitate. Both types were also supplemented with vitamin E as α-tocopherol acetate and with vitamin C as ascorbic acid. The two formulas studied had higher vitamin A (140% and 139%), vitamin E (109% and 198%) and vitamin C (167% and 118%), but lower iron (65.0% and 65.3%) and selenium (72.9% and 79.4%) than the amounts declared on the label. As expected, all the studied vitamins showed decreases during storage, and these decreases were higher in formulas stored at 40 °C. The losses of vitamin A at 40 °C after 18 months of storage were 27.5% in IF-A and 29% in IF-B, while vitamin E losses under the same conditions were 23.1% and 28.1%, and vitamin C losses under the same conditions were 28.4% and 48.6%. All these losses justify the over-fortification of the aforementioned vitamins in these LC-PUFA supplemented IFs. Iron and selenium content remained unchanged throughout storage.