Shelf-life of near-aseptically packaged refrigerated potato strips

The effect of hot water blanching and near-aseptic packaging on the shelf-life of refrigerated potato strips was investigated based on quality; microbial, textural and color. Potato strips were first blanched at low temperature (60 °C) for 10 or 20 min, and then second blanched at high temperature (∼98 °C) for 1, 5 or 10 min. Blanched potato strips were cooled and packaged into near-aseptic polyethylene bags using a near-aseptic packaging chamber. Microbial spoilage was observed for all treatments which received a second blanch of only 1-min. No microbial growth was observed within 28 days of refrigerated storage in strips treated for either 10 or 20 min in first blanch followed by 5 or 10 min in second blanch. Near-aseptically packaged refrigerated potato fries were significantly lighter in color and higher in textural quality compared to unprocessed fries (neither blanched nor near-aseptically packaged). No significant changes were observed in quality of near-aseptically packaged refrigerated potato strips during 28 days of storage at 7 ± 1 °C. These results indicate that combination of blanching and near-aseptic packaging is the better non-chemical alternative method for potato strips to extend shelf-life.     

Effect of in‐package gaseous ozone treatment on shelf life of blanched potato strips during refrigerated storage

The effect of in‐package gaseous ozone treatment on microbiological and colour quality of blanched potato strips was investigated. Potato strips were first blanched in 0.5% CaCl₂ solution at 60 °C for 10 min, second blanched in boiling water for 5 min, then exposed to room air for 30 min and packaged. Ozone gas (5%, wt/wt) was injected into each bag. Strips were subjected to a batch ozone treatment for 20 s or a continuous ozone treatment for 5, 15 or 30 min. Microbial growth was observed on day one for bags with no ozone treatment. Continuous ozone treatment was effective in extending the shelf life of potato strips compared to batch ozone treatment, and there was no microbial growth for 30‐ and 15‐min continuous ozone‐treated strips after 28 and 21 days of refrigerated storage, respectively. No significant difference was observed between the colour of blanched strips and ozone‐treated blanched strips. These results indicate that in‐package gaseous ozone treatment can be used for maintaining quality and improving shelf life of blanched potato strips.     

The effect of asparaginase on acrylamide formation in French fries

Acrylamide formation in French fries was investigated in relation to blanching and asparaginase soaking treatments before final frying. Par-fried potatoes of Bintje variety were prepared by cutting strips (0.8 × 0.8 × 5 cm) which were blanched at 75 °C for 10 min. Unblanched strips were used as the control. Control or blanched strips were then dried at 85 °C for 10 min and immediately partially fried at 175 °C for 1 min. Finally, frozen par-fried potatoes were fried at 175 °C for 3 min to obtain French fries. Pre-drying of raw or blanched potato strips did not generate acrylamide formation as expected. Partial frying of pre-dried control potato strips generated 370 μg/kg of acrylamide and the final frying determined French fries with 2075 μg/kg of acrylamide. When control potato strips were treated with a 10000 ASNU/l asparaginase solution at 40 °C for 20 min, the acrylamide formation in French fries was reduced by 30%. When blanched potato strips were treated in the same way, the produced French fries have 60% less acrylamide content than blanched strips without the enzyme treatment. Soaking of blanched potato strips (75 °C, 10 min) in an 10000 ASNU/l asparaginase solution at 40 °C for 20 min is an effective way to reduce acrylamide formation after frying by reducing the amount of one of its important precursors such as asparagine.     

Quality comparison of continuous steam sterilization segmented-flow aseptic processing versus conventional canning of whole and sliced mushrooms

Abstract: This study was carried out to investigate segmented‐flow aseptic processing of particle foods. A pilot‐scale continuous steam sterilization unit capable of producing shelf stable aseptically processed whole and sliced mushrooms was developed. The system utilized pressurized steam as the heating medium to achieve high temperature‐short time processing conditions with high and uniform heat transfer that will enable static temperature penetration studies for process development. Segmented‐flow technology produced a narrower residence time distribution than pipe‐flow aseptic processing; thus, whole and sliced mushrooms were processed only as long as needed to achieve the target F_o = 7.0 min and were not overcooked. Continuous steam sterilization segmented‐flow aseptic processing produced shelf stable aseptically processed mushrooms of superior quality to conventionally canned mushrooms. When compared to conventionally canned mushrooms, aseptically processed yield (weight basis) increased 6.1% (SD = 2.9%) and 6.6% (SD = 2.2%), whiteness (L) improved 3.1% (SD = 1.9%) and 4.7% (SD = 0.7%), color difference (ΔE) improved 6.0% (SD = 1.3%) and 8.5% (SD = 1.5%), and texture improved 3.9% (SD = 1.7%) and 4.6% (SD = 4.2%), for whole and sliced mushrooms, respectively. Segmented‐flow aseptic processing eliminated a separate blanching step, eliminated the unnecessary packaging of water and promoted the use of bag‐in‐box and other versatile aseptic packaging methods. Practical Application: Segmented‐flow aseptic processing is capable of producing shelf stable aseptically processed particle foods of superior quality to a conventionally canned product. This unique continuous steam sterilization process eliminates the need for a separate blanching step, reduces or eliminates the need for a liquid carrier, and promotes the use of bag‐in‐box and other versatile aseptic packaging methods.     

UHT Milk Processing and Effect of Plasmin Activity on Shelf Life: A Review

Abstract: The demand for ultra‐high‐temperature (UHT) processed and aseptically packaged milk is increasing worldwide. A rise of 47% from 187 billion in 2008 to 265 billon in 2013 in pack numbers is expected. Selection of UHT and aseptic packaging systems reflect customer preferences and the processes are designed to ensure commercial sterility and acceptable sensory attributes throughout shelf life. Advantages of UHT processing include extended shelf life, lower energy costs, and the elimination of required refrigeration during storage and distribution. Desirable changes taking place during UHT processing of milk such as destruction of microorganisms and inactivation of enzymes occur, while undesirable effects such as browning, loss of nutrients, sedimentation, fat separation, cooked flavor also take place. Gelation of UHT milk during storage (age gelation) is a major factor limiting its shelf life. Significant factors that influence the onset of gelation include the nature of the heat treatment, proteolysis during storage, milk composition and quality, seasonal milk production factors, and storage temperature. This review is focused on the types of age gelation and the effect of plasmin activity on enzymatic gelation in UHT milk during a prolonged storage period. Measuring enzyme activity is a major concern to commercial producers, and many techniques, such as enzyme‐linked immunosorbent assay, spectrophotometery, high‐performance liquid chromatography, and so on, are available. Extension of shelf life of UHT milk can be achieved by deactivation of enzymes, by deploying low‐temperature inactivation at 55 °C for 60 min, innovative steam injection heating, membrane processing, and high‐pressure treatments.     

Growth of Bacillus cereus on Oil-blanched Potato Strips for "Home-style" French Fries

Fresh cut, oil blanched strips from whole potatoes stored at 7 or 13 °C were inoculated with approximately 3 or 5 log CFU/g Bacillus cereus and incubated at 21 or 26.7 °C for up to 9 h to model handling of "home-style" French fries. Whole potato storage at 13 °C and incubation at 26.7 °C resulted in faster growth than 7 or 21 °C. Frying (2 to 3.5 min at 185 °C) inactivated up to 5.1 log B. cereus spores. Oil blanched potato strips for "home-style" French fries should be stored at £ 21 °C or finish fried or discarded within 3 to 4 h.     

Effect of natural antioxidants and vacuum packaging on the quality of buffalo meat nuggets during refrigerated storage

Buffalo meat nuggets (BMN) were incorporated with 500 ppm sodium ascorbate, 10 ppm -tocopherol acetate and 0.5% sodium tripolyphosphate while processing. There were three experimental groups of BMN, namely control aerobic packaged (CAP), treated aerobic packaged (TAP) and treated vacuum packaged (TVP), refrigerated and stored at 4 °C. It was observed that the treated samples (TAP and TVP) had significantly (p < 0.05) higher pH, W-B shear force, moisture and protein contents, sensory attributes and lower free fatty acids content in comparison to CAP samples. Vacuum packed nuggets (TVP) had significantly (p < 0.05) lower free fatty acid content, higher lactobacilli and total anaerobe counts and markedly higher scores for flavour and overall palatability, even at the 25th day of storage. Product quality reduced as storage time increased. Use of natural antioxidants and vacuum packaging extended the shelf life of BMN from 10 to 30 days under refrigerated storage.     

The irradiation of spices, packaging materials and luncheon meat to improve the storage life of the end products

Spices and packaging materials were exposed to γ‐irradiation at a dose of 10 kGy. Luncheon meat was prepared with irradiated or non‐irradiated spices and packaged in irradiated or non‐irradiated packaging materials. Packaged luncheon meat was treated with 2 kGy. Irradiated and non‐irradiated packaged luncheon meat were kept in a refrigerator (1–4 °C) for 12 months. Microbiological, nutritive and chemical characteristics of luncheon were evaluated after processing and during storage; whereas, sensory quality was evaluated only after irradiation. γ‐Irradiation decreased the microbiological counts of spices, packaging materials and packed products and increased its shelf‐life. No significant differences in moisture, protein, fat, pH value, total acidity, lipid peroxide and volatile basic nitrogen were observed as a result of irradiation. Sensory evaluation showed that all the combinations of treated luncheon meats were acceptable. However, the taste, odour, appearance and texture scores of irradiated packaged products were significantly lower than those of non‐irradiated samples.     

Quality Changes During Refrigerated Storage of Packaged Shrimp and Catfish Fillets Treated with Sodium Acetate, Sodium Lactate or Propyl Gallate

The effects of sodium acetate, sodium lactate, and propyl gallate were determined on microbial populations, pH, ammonia content and color of film-overwrapped or vacuum-skin packaged fresh shrimp and catfish fillets. Products were stored at 4°C up to 12 days. Vacuum-skin packaged shrimp or catfish fillets contained lower (P < 0.05) ammonia compared to film-overwrapped products. Catfish fillets treated with 2% sodium acetate had lower populations of psychrotrophic and anaerobic bacteria compared with untreated catfish, regardless of packaging. Treatment with 2% NaAc has potential for extending shelf life of refrigerated catfish fillets.     

Utilisation of modified atmosphere packaging to extend the shelf life of Khalas fresh dates

Completely matured tamr stage dates are widely available and consumed throughout the year. However, for some date varieties, the earlier khalal stage crunchy fruit is considered a premium product. This work examines the use of modified atmosphere packaging to extend the shelf life of khalal dates under refrigerated conditions. Modified atmosphere packaging with 10% or 20% CO₂ in air was successful in reducing the rate of the ripening processes while control‐packaged dates showed signs of ripening development such as significant weight loss and darkening in date colour (identified visually and as low lactic acid bacteria measurements at 18 and 27 days after packaging), similar to that observed in tamr stage fruit.     

PA/PE复合膜对鲜切莴笋保鲜效果的影响

为了验证尼龙-聚乙烯（polyamide/polyethylene,PA/PE）复合膜对鲜切莴笋的保鲜效果,将新鲜莴笋切片真空包装后在4 ℃条件下冷藏,不加任何包装的鲜切莴笋同样条件下作空白对照。贮藏期间评价菌落总数、色差、pH值、汁液流失率、VC含量、感官等指标。结果PA/PE组贮藏期达24 d,而不加包装的对照组只有4 d。可见对于鲜切莴笋的贮藏,PA/PE复合膜结合真空包装可明显延长其贮藏期。     

Packaging optimisation for portioned Canestrato di Moliterno cheese

Different polymeric films and various headspace conditions (air, vacuum and four different modified atmosphere packaging) were combined to select a packaging system that assured the desired shelf life for two types of portioned Canestrato di Moliterno cheese ripened for 4 and 12 months. To evaluate the quality deterioration of the packaged cheese samples under refrigerated conditions, texture change, weight loss, water activity, moisture content, microbial contamination, pH and sensory attributes were monitored during storage. The results highlighted that a high‐barrier multilayer film delayed proliferation of moulds and gave the best results for both types of ripened cheese.     

Quorum Sensing Involved in the Spoilage Process of the Skin and Flesh of Vacuum‐Packaged Farmed Turbot (Scophthalmus maximus) Stored at 4 °C

Fish skin has both positive and negative effects on the shelf‐life of the fish. This study aimed to investigate the spoilage process of the skin and flesh of refrigerated farmed turbot (Scophthalmus maximus) with vacuum packaging. Microbial community changes were analyzed by combining culture‐dependent and culture‐independent methods. The results indicated that the shelf‐life of vacuum‐packaged refrigerated turbot was 16 d; skin mucus was the interference factor of turbot quality. The culture‐dependent analysis demonstrated that the total viable counts and the population of H₂S‐producing bacteria, Pseudomonas spp., Enterobacteriaceae spp., and lactic acid bacteria in skin had a range of 0.45 to 1.40 log (CFU/g) higher than the microbial numbers in flesh after 16 d in storage. 16S high throughout sequencing results demonstrated that the compositions of spoilage microbes were similar in skin and flesh. Shewanella spp., followed by Carnobacterium spp., was the dominant spoilage organism at day 16. Quorum sensing (QS) signaling activity increased during the storage. Exogenous N‐butanoyl‐L‐homoserinelactone(C4‐HSL) and N‐hexanoyl‐Lhomoserine lactone (C6‐HSL) significantly accelerated the spoilage process of refrigerated turbot, while the addition of 4, 5‐Dihydroxypentane‐2, 3‐dione (DPD) prolonged the lag phase duration. Therefore, QS may be involved in the spoilage process of refrigerated turbot.     

Shelf‐life extension of fresh‐like ready‐to‐use pear cubes

Minimally processed fruit and vegetables are generally more perishable than the original raw materials due to the injury stresses during preparation that greatly increase tissue respiration and lead to deterioration through various biochemical pathways. In this paper, the effects of low intensity blanching treatments on enzymatic and microbiological stability on the fresh‐like quality of ready‐to‐use pear cubes has been evaluated. Blanching treatments as well as packaging were carried out both in aseptic and in non‐aseptic conditions. The combination of low intensity blanching with superficial enzymatic treatments has been carried out. The results confirm that the combination of a mild heat treatment (3 min at 95 °C) under aseptic conditions is enough to enhance the stability of this minimally processed product with an acceptable reduction in the texture. The superficial treatment with lysozyme did not result in an improvement in the stability of the blanched pear cubes during storage under refrigerated conditions. © 1999 Society of Chemical Industry     

Optimization of the blanching process to reduce acrylamide in fried potatoes

A central composite design was used to study the effect of blanching time and temperature on the extraction of reducing sugars from potato strips and slices. After frying, the impact of both factors on the acrylamide content in French fries and potato crisps was evaluated. Acrylamide could be lowered more efficiently in potato crisps compared to French fries, due to a more pronounced extraction of sugars from potato slices upon blanching. In both products, blanching temperature was the main influencing factor for sugar extraction and subsequent acrylamide mitigation. Blanching at temperatures of about 70 °C for a short period of time (about 10 min) was more efficient compared to blanching at lower temperatures, which appeared more time-consuming. However, the extraction efficiency of reducing sugars was over 10% lower when the potato cuts were blanched in water which was previously used for blanching, leading to over 10% less reduction in the final acrylamide content.     

Effect of Initial Headspace O2 Level on the Growth and Volatile Metabolite Production of Leuconostoc Mesenteriodes and the Microbial and Sensorial Quality of Modified Atmosphere Packaged Par‐Fried French Fries

This study evaluated the effect of residual O₂ level (0% to 5%) on microbial growth and volatile metabolite production on par‐fried French fries packaged in a modified atmosphere with 60% CO₂ (rest N₂) at 4 °C. The results obtained showed that the initial headspace (IH) O₂ level had an effect on growth of Leuconostoc mesenteroides on French fry simulation agar, whereby growth was slightly faster under 5% O₂. In terms of quantity, ethanol, 2‐methyl‐1‐propanol, and dimethyl disulphide were the most significant volatile metabolites produced by L. mesenteroides. The production of ethanol by L. mesenteroides was highest on simulation agar packaged under low IH O₂ levels (0% to 1%), indicating that the fermentative metabolism was induced under these conditions. In agreement with the results observed on the simulation medium, growth of native lactic acid bacteria was faster under an IH O₂ level of 5%. In addition, ethanol, 2‐methyl‐1‐propanol, and dimethyl disulphide were also quantitatively the most important volatile metabolites. However, in contrast, greater quantities of ethanol and dimethyl disulphide were produced on par‐fried French fries packaged under 5% O₂. This was attributed to the limited growth of the native flora on the par‐fried French fries under residual O₂ levels of 0% and 1%. Although some significant differences (P < 0.05) occurred between the French fries packaged in 0%, 1%, and 5 % residual O₂ during storage, all products were considered to be acceptable for consumption. The results of this study can be used to optimize the shelf‐life of packaged chill stored potato products.     

Sodium lactate addition on the quality and shelf life of refrigerated sliced poultry sausage packaged in air or nitrogen atmosphere

The aim of this study was to determine the effect of sodium lactate addition on shelf-life extension of sliced poultry sausage packaged both in air and nitrogen atmospheres and stored in refrigerated conditions. Basic chemical composition, pH, and malonaldehyde content were assayed and color measurement using the reflection method was carried out. Microbiological examination consisted of determination of total number of aerobic psychrotrophic bacteria and number of lactic acid bacteria. Sensory evaluation of products was performed. Microbiological and sensory quality of sliced poultry meat sausage was dependent on the addition during production of sodium lactate and the composition of gases (air or nitrogen) used in packaging. Slices of poultry sausage with 1% as well as 2% of sodium lactate maintained their initial quality of evaluated sensory attributes longer, irrespective of the applied gases. Sodium lactate inhibited growth of aerobic psychrotrophic bacteria and lactic acid bacteria during refrigerated storage. Sodium lactate also inhibited the formation of malonaldehyde in sliced poultry sausage during refrigerated storage. The effectiveness of this process depended on the concentration of sodium lactate addition. It was concluded that 1% as well as 2% addition of sodium lactate could extend the shelf life of sliced poultry sausage packaged in air atmosphere and stored at 5 to 7 degrees C by 3 or 4 times, respectively. Sliced poultry sausage treated with 2% sodium lactate packed in nitrogen had the longest (35-day) shelf life. This was a sevenfold increase in the shelf life of sliced poultry sausage compared with the control.     

Tastier and Healthier Alternatives to French Fries

ABSTRACT: The effect of both the origin and shape of potato cuts on fry quality was investigated in this study. Linear strips from the inner core of tubers were compared to those from outer tissues, both before and after processing, and strips from either specific tissues or whole peeled tubers were also evaluated against ring-shaped cuts. Both strips and rings had 0.7 cm sides and, in most cases, a volume of 4.9 cm³. They were analyzed for moisture content, antioxidants, asparagine, and reducing sugars. The material was then blanched, dipped in 0.5% disodium acid pyrophosphate and 0.3% glucose, dried at 77 °C, par-fried in soybean oil at 191 °C, and finish-fried at 168 °C. The fried product was analyzed for sensory characteristics and oil, salt, and acrylamide content. Our results showed that strips from the inner core absorbed 28% more oil and exhibited inferior sensory characteristics compared to strips from the outer parts. The extended drying and frying times needed to match the crispness and flavor of inner strips to those of regularly fried outer strips resulted in a further increased absorption of oil and, importantly, triggered a 163% increase in levels of the toxic Maillard reaction product acrylamide. Potato rings consisted of higher dry matter material, contained more antioxidants, and had a lower surface-to-volume ratio than the conventional linear strips. Upon processing, they also absorbed 22% less oil, contained 26% less salt, and displayed superior sensory properties. Thus, ring fries may represent an attractive alternative to French fries as processed staple food.     

The microbial safety of strawberry and raspberry fruits packaged in high-oxygen and equilibrium-modified atmospheres compared to air storage

Microbial safety of strawberry and raspberry fruits was assessed after shelf‐life extension by two new packaging systems, high‐oxygen atmospheres (HOA) and equilibrium‐modified atmospheres (EMA), in combination with an ethylene absorbing film. Both fruits had a shelf‐life of 3 days at 7 °C when macroperforated films were used. Strawberry fruits were acceptable for 5 days in both packages, raspberries had a shelf‐life of 7 and 5 days when using EMA and HOA respectively. Escherichia coli, Salmonella spp. and Listeria monocytogenes were artificially inoculated onto packaged fruits. All were able to survive on packaged fruits stored at 7 °C. Raspberries showed an enhanced inactivation of Salmonella during storage time in both types of packaging. Growth of L. monocytogenes was observed on the calyx of strawberries after the end of the established shelf‐life. Generally, increasing the shelf‐life of the fruits with EMA and HOA did not give an increased microbial risk.     

Changes of polysaccharide content and texture of potato during French fries production

The purpose of the present study was to determine the changes in non-starch polysaccharide and lignin contents of potato during French fries production and also the relationship between the texture of the finished product and half-products, as a result of processing at each stage under investigation. The samples for laboratory studies were taken from potato tubers, strips and French fries collected from nine locations of a technological line. The greatest changes in non-starch polysaccharide content and texture of potatoes resulted from blanching and frying. The texture of French fries was mainly affected by pectin and cellulose. The texture of French fries can be predicted from the measurements of the texture of potato strips after blanching.