EXTENSION OF THE SHELF-LIFE OF BURFI BY PACKAGING

Burfi, an Indian milk‐based sweet, is susceptible to microbial spoilage that restricts its shelf life to 10 days. Large‐scale marketability of burfi and its export potential requires longer shelf life. Therefore, our aim was maximizing shelf life by packaging means. Studies were carried out on burfi in different packaging materials under different atmospheres – normal packing, vacuum packing and use of a free‐oxygen absorber – at 65% RH/27C. Normal packing even in barrier film did not effectively control microbial spoilage. Vacuum packing, although it retarded microbial growth, adversely affected texture and sensory quality. A free‐oxygen absorber coupled with high‐barrier materials like metallized films/foil laminates offered more than 45 days shelf life. Stored samples could be grouped by principal component analysis. The major sensory attributes contributing to grouping were color, firmness, chewiness, creamy and rancid notes. Sensory firmness and chewiness were found to have good correlation with instrumentally measured texture values.     

SHELF-LIFE EXTENSION BY PHENYLGLYOXAL OF CLOSTRIDIUM SPOROGENES-INOCULATED VACUUM-PACKAGED GROUND BEEF

Phenylglyoxal (PG), an aromatic α-dicarbonyl, is used in a variety of industrial, medical, and biological research applications. The compound delays spore germination and inhibits vegetative cells of both aerobic and anaerobic sporeforming bacteria, interacts with several critical bacterial growth factors, and is structurally similar to a number of approved food flavoring agents. Previous research demonstrated inhibitory activity against Clostridium sporogenes in model systems. Therefore, we investigated the shelf-life enhancing effectiveness of PG in C. sporogenes-inoculated vacuum-packaged ground beef at 32C. During extended incubation under temperature abuse conditions, PG delayed undesirable color changes and prevented organoleptic spoilage. Five μg PG/g inhibited proteolysis, while 156 μg PG/g delayed conversion of myoglobin to metmyoglobin, prevented H₂S production, maintained product quality and texture for 25 days, and reduced thermal resistance of C. sporogenes spores at 90C. The observed activity of PG suggests that similar activity might be found with currently approved α-dicarbonyls. Furthermore, the compound's effect on thermal resistance may serve as an example of compounds that could be used to reduce thermal processing requirements of heat-sensitive and/or minimally processed foods.     

SHORT-TERM CONTROLLED ATMOSPHERE STORAGE FOR SHELF-LIFE EXTENSION of APRICOTS1

Shelf-life of ‘Perfection’ and ‘Rival’ apricots can be enhanced with the use of controlled atmosphere (CA) storage. Apricots were harvested at commercial maturity and immediately stored in CA at 1 or 2% 0₂ and 3, 6, 9, 12 or 15% C0₂ for 30, 45 and 60 days. No differences in fruit quality were evident between 02 atmospheres of 1 and 2%, except that fruit stored in 1 % 02 displayed less rot development and higher acid content. Apricots stored in 9% or less C0₂ displayed reduced external and internal color, inadequate finish, increased internal breakdown and more rot development with unacceptable firmness retention for additional handling. Apricots stored in 12 or 15% CO₂ retained firmness and displayed enhanced finish with reduced rots and very little internal breakdown with storage duration of 60 days. Color was much slower to develop in apricots stored in 12 or 15% CO₂ for all storage periods.     

OSMOTIC DEHYDRATION OF APPLES BY IMMERSION IN CONCENTRATED SUCROSE/MALTODEXTRIN SOLUTIONS

The effect of sucrose:maltodextrin (S:M100) ratios on solids gain (SG) and water loss (WL) was investigated during the osmotic dehydration of apple disks. Concentrated solutions were prepared at 40C with 100:0, 90:10, 70:30, 50:50, 30:70 and 10:90 ratios of (S:M100). The highest score in sensory evaluation was achieved with 90:10 ratio of (S:M100). Three stages of osmotic dehydration can be observed by plotting the shrinkage of apple disks vs the moisture content. The result is that a higher maltodextrin concentration favors volume loss and enhances water loss, increasing the duration of stage 2 osmotic dehydration.     

THE EFFECT OF ULTRAVIOLET IRRADIATION ON SHELF-LIFE AND RIPENING OF PEACHES AND APPLES

“Loring” and “Elberta” peaches and “Golden Delicious” apples were irradiated with UV (254nm) to doses of 0.84 × 10⁴ to 40 × 10⁴ erg/mm² then stored. “Loring” were stored 10 days and “Elberta” 20 days at 12°C. “Golden Delicious” were stored 30 days at 20–25°C in a dark room. Fruit were examined and differences in percentage rot and in physical-chemical properties determined. Percentage rot decreased with increasing UV dose. Fruit were firmer, pH and soluble solids lower and acidity higher for UV-treated than for nontreated peaches; pH was lower and acidity and ascorbic acid higher in UV treated than in nontreated apples. Percentage weight loss was less for UV-treated apples. The results indicated that UV treatment not only reduced storage rots but also delayed ripening of peaches and apples.     

MEALINESS DETECTION IN APPLES USING TIME RESOLVED REFLECTANCE SPECTROSCOPY

Mealiness is a textural attribute related to internal fruit disorder that is characterized by the combination of abnormal softness of the fruit and absence of free juiciness in the mouth when eaten by the consumer. Time‐resolved laser reflectance spectroscopy was used as a tool to determine mealiness. This new technique in agrofood research may provide physical and chemical information independently and simultaneously, which is relevant to characterize mealiness. Using visible and near infrared lasers as light sources, time‐resolved laser reflectance spectroscopy was applied to Golden Delicious and Cox apples (n = 90), to characterize batches of untreated samples and samples that were stored under conditions that promote the development of mealiness (20C & 95% RH). The collected database was clustered into different groups according to their instrumental test values. The optical coefficients were used as explanatory variables to build discriminant functions for mealiness. The performance of the classification models created ranged from 47 to 100% of correctly identified mealy versus nonmealy apples.     

阳离子染料可染涤纶纤维的染色工艺

从染色工艺方面对阳离子可染改性涤纶的染色性能进行了研究.通过逐次改变单一因素保持其他因素不变的方法进行对比试验,测定各实验组纤维上染百分率,并进一步探讨了染料用量、酸度、助剂用量和时间对染色性能的影响.得出阳离子染改性涤纶的最佳染色工艺为:染料用量0.5%(owf),匀染剂1227用量O.5%(owf),醋酸钠用量1....     

SHELF-LIFE EXTENSION OF TILAPIA IN CRUSHED ICE WITH ADDITIVES AT −3C

Thirty-six experiments were carried out with potassium sorbate, citric acid and ascorbic acid at 0, 0.1, 0.15 and 0.2% in separate and mixed forms added to water to produce ice for storing tilapia at −3C for 15 days. Every three days chemical indicators trimethylamine and hypoxanthine as well as psychrotrophic bacteria counts were determined.
Fish stored in crushed ice with additives have markedly lower changes in trimethylamine and hypoxanthine with storage compared to iced controls. By linear regression analysis of 36 treatments, the following six treatments were best: 0.2% ascorbic acid, 0.15 or 0.2% citric acid, and 0.1, 0.15 and 0.2% potassium sorbate. These six treatments were not statistically different due to trimethylamine, hypoxanthine content nor due to psychrotrophic bacteria growth during storage. Probably, the treatment with the lowest concentration of citric acid (0.15%) and potassium sorbate (0.1%) should be considered as the best.     

THE SHELF-LIFE EXTENSION OF HADDOCK IN CARBON DIOXIDE-OXYGEN ATMOSPHERES WITH AND WITHOUT POTASSIUM SORBATE

Fresh haddock, whole fish or fillets, treated or not with various potassium sorbate dips, were sealed in gas impermeable bags containing gas atmospheres of 60% CO₂, 20% O₂ and 20% N₂, air or vacuum, stored on ice in insulated AIRBOX containers at 0°C and subsequently assessed using the Torry freshness scale after 11 to 18 days storage. The trends in the data suggested higher freshness scores for gas and gas plus dip compared with the air and vacuum packs. The dip alone was not effective. It was important to maintain the fish at 0° C.     

USING GELATIN-BASED ANTIMICROBIAL EDIBLE COATING TO PROLONG SHELF-LIFE OF TILAPIA FILLETS

Skinless tilapia (Dreochromis niloticus x D. aureus) fillets were covered with a gelatin coating containing benzoic acid as an antimicrobial agent. Benzoic acid content of fish fillets was used to estimate the amount of gelatin coated on fillet surface, and it was found that the gelatin contents were between 16.3 mg and 17.3 mg per g of fillets. Aerobic and anaerobic microbial loads, volatile basic nitrogen (VBN) contents, and sensory evaluation were used as indicators to survey the feasibility of an antimicrobial gelatin coating to prolong the shelf‐life of tilapia fillets under refrigeration. After 7 days of storage under refrigeration, tilapia fillets coated with gelatin containing benzoic acid had acceptable VBN contents, increased moderately in microbial loads, and showed no significant sensory difference (P < 0.05) from fresh fillets. The results indicate that an antimicrobial gelatin coating is suitable for preservation of tilapia fillets.     

SHELF-LIFE EXTENSION AND SAFETY CONCERNS ABOUT FRESH FISHERY PRODUCTS PACKAGED UNDER MODIFIED ATMOSPHERES: A REVIEW

Shelf-life and quality of fresh fishery products can be extended by the use of a modified atmosphere (MA) and high barrier film packaging coupled with refrigerated storage. MAs with elevated levels of carbon dioxide inhibit or slow the growth of various aerobic spoilage bacteria of fishery products by extending the lag phase. However, at the same time, MAs provide conditions for the growth of Grampositive bacteria and food pathogens within the package. The extension of the storage life of the refrigerated MA products may enable the slower-growing Gram-positive bacteria to reach high populations. The shelf-life of fishery products packaged under MAs rich in carbon dioxide coupled with storage at 8.0°C or below can be extended more than 100%. Major safety concerns regarding the risk of foodborne botulism can result from MA packaging of fresh fishery products that contain the spores of nonproteolytic C. botulinum and are subsequently temperature-abused. Minimizing the risk of foodborne botulism by including inhibitory factors such as antimicrobial agents before packaging fishery products under MAs and strict adherence to refrigerated storage temperatures are discussed.     

SHELF-LIFE EXTENSION OF RAW BROWN SHRIMP (PENAEUS AZTECUS) WITH POTASSIUM SORBATE IN ICES AND DIPS

The shelf-life of shrimp, as indexed by psychrotrophic bacterial counts, was extended approximately 1.0, 1.9, and 3.1 days using levels of 0.05%, 0.1%, and 0.2% potassium sorbate-containing ice, respectively. Shelf-life was extended an additional 0.5 to 2.5 days when a 3% potassium sorbate dip was administered prior to storage on modified ice. In all cases, potassium sorbate extended the lag phases of the spoilage bacteria.     

利用生物传感器检测植物组织中蔗糖含量的变化

采用生物传感器检测方式测定梨和海棠两种作物不同时期、不同部位的蔗糖含量,结果显示,作物的蔗糖含量与总光合源呈正相关,光照天数越多,时间越长其含量就要越高,此外果实积累、贮存蔗糖还与茎的运输能力,果实的卸糖能力密不可分。     

THE EFFECTS OF USING ALTERNATIVE SWEETENERS TO SUCROSE ON ICE CREAM QUALITY

In this study, seven different ice cream samples were produced using sucrose, high fructose corn syrup (HFCS), glucose syrup (GS), honey, sucrose  +  GS, sucrose  +  HFCS and sucrose  +  honey mixtures (1/1). The ice cream samples containing only sucrose were used as control.
The acidity values of the samples with sucrose and GS were lower than those of the others. The viscosity value of the sample containing honey and stored for 15 days was the lowest. When honey together with sucrose (1/1) was added to the ice cream mixture, the viscosity increased. On the other hand, using honey increased the fat destabilization value. The overrun ratio of the sample with sucrose was the highest. The lowest melting ratio was determined in samples containing GS at the beginning of storage period. The melting ratios of the ice creams slightly increased during 15 days of the storage. The highest glucose and fructose amounts were observed in the samples made with honey. Panellists preferred the ice cream samples with sucrose  +  GS compared to control and the other samples.

PRACTICAL APPLICATIONS

Due to increasing consumer demands for low calorie foods, products made with alternative sweeteners have became more popular recently. Changing attitudes in sucrose consumption have heightened because of its causing effect to diabetes and obesity. Therefore there is a need for evaluating the alternative sweeteners. Although there were many studies about ice cream in the literature, there are few studies on using different sugars in ice cream production.     

SHELF-LIFE OF FRIED POTATO CHIPS USING RBD PALM OLEIN, SOYBEAN OIL AND THEIR BLENDS

Shelf-life of potato chips fried in refined, bleached and deodorized palm olein (RBDPO), soybean oil (SBO) and their blends was evaluated. Potato slices were fried for 130 s at 180 PT 5C at 30 min intervals over a period of 5 h/day for 5 consecutive days. Indicators of frying oil quality with the shelf-life of fried products chosen were total polar component and acid value. This study indicated that RBDPO was better than SBO for the preparation of fried potato chips in terms of shelf-life of products. The blends were also slightly better than SBO with increasing proportion of RBDPO. However, the effects were minimal on the rate of development of rancidity in fried products beyond the fourth day of frying in the frying medium.