Effect of pasteurisation on sensory quality of natural soursop puree under different storage conditions

Pasteurisation effects on natural soursop (Annona muricata L.) puree were evaluated in terms of appearance, colour, flavour, odour, consistency and overall acceptability for 12 weeks. The packaging and storage temperature combinations used were laminated aluminium foil (LAF), lacquered can (LC) and high density polyethylene plastic bottle (HDPE) at ambient temperature (28–38°C), 15, 4 and −20°C. Results showed pasteurisation at 79°C for 69 s significantly improved the sensory colour, flavour, appearance and overall acceptability of the puree. Pasteurised puree packed in LAF at 4°C had the highest score for almost every attribute evaluated. Overall, all samples were found acceptable by judges during the 12 week storage period. The better stability, in terms of colour, consistency and flavour characteristics, of pasteurised puree packed in foil at 4°C than the frozen control could be an additional and cheap advantage for storage and transport.     

Quality changes during the storage of apple puree

The stability of apple puree at different constant temperatures (-18°C, 4°C, 20°C, 50°C and 60°C) was studied within the period of 30 days. During this time changes in the samples of apple puree, which was stored at variable temperature, were determined as well. The content of ascorbic acid, the sucrose inversion, the formation of furfural and levulinic acid as well as sensory properties were followed as criteria of the puree quality. From obtained data the temperature dependence of these reactions was derived. On this base the shelf life of apple puree (the time, after which the sensory differences became significant) was estimated. This period was relatively short, i.e. less than 100 days at 20°C. The changes in puree at variable temperature were similar to those at higher storage temperatures (40°C–50°C).     

Changes in carotenoids during processing and storage of pumpkin puree

Changes in the contents of carotenoids and their true retentions (% TR) during the production of puree of Cucurbita moschata ‘Menina Brasileira’ and of Cucurbita maxima ‘Exposição’ pumpkins and the stability of such compounds during 180 days of storage were monitored by liquid chromatography coupled with a photodiode array detector. Cooking caused higher losses than commercial sterilisation. High losses of xanthophylls such as lutein and violaxanthin were noted during processing and storage of pumpkin puree. Such losses show the low stability of these compounds. The major carotenoids, pro-vitamin A carotenes, namely, α-carotene and all-trans-β-carotene for C. moschata ‘Menina Brasileira’ and all-trans-β-carotene for C. maxima ‘Exposição’ obtained high retentions (>75%) after processing. A slight degree of isomerisation of β-carotene was noted in the puree samples, but with low concentrations of cis-isomers. Storage for 180 days did not significantly affect (P ? 0.05) the concentrations of these carotenoids.     

苹果泥加工及储藏过程中6种农药残留变化

目的 明确苹果泥加工及储藏过程中多菌灵、噻虫嗪、吡虫啉、啶虫脒、咪鲜胺和苯醚甲环唑残留变化规律。方法 通过实验室模拟加工和加速储藏实验, 采用液相色谱-质谱法检测其中多菌灵、噻虫嗪、吡虫啉、啶虫脒、咪鲜胺和苯醚甲环唑的残留变化。结果 建立的检测方法中, 6种农药回收率范围为80.48%~114.58%, 相对标准偏差为2.08%~6.43%, 检出限为0.10~1.25 μg/kg, 定量限为0.50~5.00 μg/kg。苹果泥加工过程中清洗步骤农药残留浓度降低12.93%~38.87%, 预煮步骤农药残留浓度降低24.61%~58.16%, 而巴氏杀菌步骤农药残留浓度略有增加(P>0.05)。加速储藏过程中6种农药残留浓度均降低, 其中咪鲜胺在加速储藏14 d后未检出。苹果泥加工全程及储藏过程中6种农药的加工因子均小于1。结论 研究结果可为苹果泥中农药最大残留限量制定及消费者安全膳食引导提供参考, 获得的加工因子可用于食品安全风险评估, 提升风险评估结果的准确性。     

贮藏温度对草莓浆理化成分和品质变化的影响

探明贮藏条件对草莓浆理化成分和品质的影响。研究了常温(25℃)、0、4、-18℃冷冻贮藏期间草莓浆花色苷、V_C、可滴定酸、可溶性固形物、风味的变化。结果表明,贮藏60 d,常温和4℃冷藏草莓浆花色苷保留率为12.56%和70.6%,0℃和-18℃冷冻贮藏草莓浆花色苷保留率仍在88%以上,常温和4℃贮藏V_C保留率分别为42.26%和73.21%,0℃和冷冻贮藏V_C保留率均为90%以上;可滴定酸和可溶性固形物在0℃和冷冻贮藏60 d内无显著变化;0℃和冷冻贮藏草莓浆的色泽明显优于常温贮藏;-18℃冷冻贮藏可以较好的保持草莓浆的酸味、甜味等味觉感官品质。经综合评价,0℃和-18℃冷冻环境条件有利于草莓果浆品质的保持,可显著延缓花色苷和V_C的降解,是较合适的草莓浆保藏温度,为草莓浆加工与保藏提供了参考。     

Microbial and chemical changes in 'Sobrasada' during ripening

‘Sobrasada’ is a raw-cured product typical of Mallorca (Balearic Islands). Throughout its ripening process the product, like other raw-cured sausages, undergoes a series of chemical and microbial changes which lead to the formation of its desirable final characteristics.In the ‘sobrasada’ studied, the breeds, feeding and casings used in the Balearic Islands were employed. The evolution of different groups of microorganisms was followed: mesophylic aerobic microorganisms, lactic acid bacteria, Enterobacteriaceae, yeasts and moulds, group D Streptococcus, proteolytic microorganisms and lipolytic microorganisms. It was found that the predominant flora, from the beginning to the end, was made up of lactic acid bacteria. Conversely, Enterobacteriaceae disappeared as ripening went on, and the rest of the microbial groups studied underwent little variation along the process.An important characteristics of the product is the fast fall of pH, from values near 6·0 to values around 5·3, in the first week.     

Quality and consumer acceptance of radio frequency and traditional heat pasteurised kiwi puree during storage

To explore the feasibility of using radio frequency (RF) heating as a method to process kiwi puree, this study compared the effects of RF heating with traditional heat pasteurisation (TP) on various properties of kiwi puree. RF treatment completely inactivate of microbes in kiwi puree, with total aerobic bacteria counts (TAC) decreased by 4.81 log CFU mL^?1 and yeast and mould counts (YMC) decreased by 2.62 log CFU mL^?1, which are similar to TP treatment. During the 7 weeks’ storage, RF‐treated puree showed retarded growth of microbes. The pH, titratable acidity and °Brix values of RF‐treated samples were significantly different from those of the control. The vitamin C, total phenolic compounds and antioxidant capacity of RF‐treated samples were significantly higher than those of TP‐treated samples during storage. RF‐treated sample retained better colour than TP‐treated sample throughout storage. The customer satisfaction analysis indicated that consumers prefer RF‐treated kiwi puree than TP‐treated samples. These findings suggest that RF heating has potential applications in processing of kiwi puree or similar products.     

Microbial community changes in Makgeolli during brewing

Makgeolli, a traditional Korean alcoholic beverage, is produced from the simultaneous saccharification and fermentation of glutinous rice by microbes introduced through nuruk (fermentation starter). The microbial community in Makgeolli is complex, and changes in the community are important for quality control and product development of Makgeolli. In this study, changes in the microbial community of Makgeolli during brewing were monitored by pyrosequencing. Pyrosequencing of microbes in Makgeolli illustrated dynamic changes in the populations and species of bacteria and fungi during brewing. Saccharomyces, a fungal genus, dominated the fungal community in Makgeolli throughout brewing, and produced alcohol after sufficient production of reducing sugars. As the bacterial genera Pediococcus, Weissella, Lactobacillus and Enterococcus, categorized as lactic acid bacteria, grew in Makgeolli, the pH decreased. The fungal community in Makgeolli was not significantly changed during brewing, but there were dynamic changes in the bacterial community, especially during the first 2 days of brewing. Copyright © 2015 The Institute of Brewing & Distilling     

Kinetic models of non‐enzymatic browning in apple puree

The effects of thermal treatments on 11 °Brix apple puree were studied at temperatures from 80 to 98 °C. Colour changes (measured by reflectance spectroscopy, colour difference, L*, a* and b* and the evolution of 5‐hydroxymethylfurfural (HMF) and sugars (hexoses and sucrose) were used to evaluate non‐enzymatic browning. A kinetic model based on a two‐stage mechanism was applied to the evolution of colour difference and a*. A first‐order kinetic model was applied to L* evolution, while the evolution of absorbance at 420 nm (A₄₂₀) of the liquid fraction was described using a zero‐order kinetic model. Thermally treated samples became more reddish and suffered a slight loss of yellow hues. The effect of temperature on the kinetic constants was described by an Arrhenius‐type equation. The presence of pulp in the samples led to activation energies for A₄₂₀ and sucrose which were lower than those found previously for clarified juices with the same soluble solids content. © 2000 Society of Chemical Industry     

Microbial changes and growth of Listeria monocytogenes during chilled storage of brined shrimp (Pandalus borealis)

Thirteen storage trials and ten challenge tests were carried out to examine microbial changes, spoilage and the potential growth of Listeria monocytogenes in brined shrimp (Pandalus borealis). Shrimp in brine as well as brined and drained shrimp in modified atmosphere packaging (MAP) were produced and studied. Different recipes were used to study the effect of preserving parameters (organic acids, pH and NaCl) on growth of microorganisms and shelf life at 7-8 degrees C or 12 degrees C. Particularly, brines with different concentrations of (i) benzoic, citric and sorbic acids or (ii) acetic, citric and lactic acids were studied. Furthermore, the effect of adding diacetate to brined shrimp was evaluated. A single batch of cooked and peeled shrimp was used to study both industrially and manually processed brined shrimp with respect to the effect of process hygiene on microbial changes and the shelf life of products. Concentrations of microorganisms on newly produced brined shrimp from an industrial scale processing line were 1.0-2.3 log (CFU g(-1)) higher than comparable concentrations in manually processed samples. This resulted in a substantially shorter shelf life and a more diverse spoilage microflora of the industrially processed brined shrimp. In addition, shelf life of brined shrimp was affected by the types and concentrations of organic acids and by the storage temperature as expected. The effect of MAP was less pronounced. Eighty-two isolates from the spoilage microflora of brined shrimp were identified and they included 53 lactic acid bacteria, 6 coagulase negative Staphylococcus spp., 18 Pseudomonas fluorescens and 5 yeast isolates. After storage at 7 degrees C, P. fluorescens, Enterococcus-like isolates, E. malodoratus, Carnobacterium maltaromaticum, coagulase negative Staphylococcus spp. and Lactobacillus sakei constituted the dominating microflora of shrimp in brines that contained benzoic, citric and sorbic acids as preservatives. L. sakei dominated the spoilage microflora of brined and drained MAP shrimp, and of brined shrimp preserved using acetic, citric and lactic acids, irrespective of packaging conditions. Shrimp in brine with benzoic, citric and sorbic acids prevented growth of L. monocytogenes during more than 40 days at 7 degrees C when the preserving parameters resembled those of commercial products. However, small changes in the preserving parameters and, particularly, reduced concentrations of benzoic acid led to growth of L. monocytogenes in brined shrimp. The present study provides significant new information on microbial changes, shelf life and growth of L. monocytogenes in brined shrimp. This information can facilitate development of new and safe brined shrimp products.     

Non-enzymatic browning in peach puree during heating

Non-enzymatic browning in peach puree (11° Brix) due to extended thermal treatment was investigated. Absorbance at 420 nm, colorimetric parameters (CIE L*, a*, b* and ΔE*), content in sugars (fructose, glucose and sucrose) and hydroxymethylfurfural were used to estimate the extent of nonenzymatic browning during heating at high temperatures (80, 85, 90, 95 and 98°C) for 480 min. Zero and first order kinetics were applied to describe evolution of relative absorbance at 420 nm. Relative luminosity and sucrose content follow a first order kinetic. Colour difference was successfully adjusted to a model including two stages: the first one includes the colour formation and it follows a kinetic of order zero and the second includes the colour destruction and it follows a first order kinetic model. Both first and autocatalytical models can describe HMF formation. Parameter b* was significantly reduced with heating time, especially at higher temperatures, on the contrary parameter a* increases during heating. The Arrhenius model described well the temperature dependence of the reaction rate constant for all the parameters considered.     

Microbiological changes in mayonnaise-based salads during storage

Within 6 h of manufacture of coleslaw, Florida, potato, Spanish and vegetable salads the concentration of acetic acid in the mayonnaise component decreased by absorption into the plant tissue, and the pH increased. Except in Spanish salad, where the concentration of acetic acid remained at an inhibitory level, these changes allowed the growth of microorganisms in salads stored at 10°C, but not at 5°C, and emphasized the need for careful control of temperature during the distribution and sale of these products.     

Effect of magnetic field with different dimensions on quality of avocado puree during frozen storage

The magnetic field-assisted freezing (MFAF) has been identified as an emerging physical method used for food preservation, characterised by its high penetrability in food materials. However, effects of magnetic fields in different dimensions on food freezing process and its products quality have not been previously compared. Thus, the alternating magnetic fields (4 mT and 50 Hz) were applied in different directions and its impact on the physiochemical properties of frozen avocado puree during the storage were investigated. In comparison with the conventional freezing process, the application of MFAF could reduce the weight loss and soluble solids rise. The transformation between different types of water and their corresponding redistribution were also limited under MFAF. The decrease of total polyphenol content with extended storage time was reduced due to the inhibitory effect of MFAF on the polyphenol oxidase activity. In general, the MFAF of avocado purees presented better texture characteristics and higher sensory qualities than the controls. The more directions the magnetic field was applied, the better it performed in maintaining the quality of avocado puree. This study provides a reference for the application of the MFAF on food cryopreservation.     

Microbial and sensory changes during refrigerated storage of desalted cod (Gadus morhua) preserved by combined methods

Water blanching and the use of additives (potassium sorbate and citric acid) combined with different types of packaging (air, vacuum "VP" and modified atmosphere packaging "MAP": 60% CO(2), 30% N(2) and 10% O(2)), were studied as new methods of preservation of chilled desalted cod. Microbial counts and total volatile basic nitrogen (TVB-N) analyses were carried out during a period of 42 days on all samples stored at 4 degrees C. No Aeromonas or sulphite-reducing Clostridium were isolated from any of the analysed samples. The lowest microbial counts of mesophilic, psychrotrophic, Pseudomonas, moulds and yeasts, were found in samples with additives in all kinds of packaging. These samples in VP or MAP maintained an excellent microbial quality throughout the 42 days of storage, with mesophilic and psychrotrophic counts always below 4 log CFU/g. Counts of the four microorganisms above-mentioned in blanched samples packaged with air, exceeded 5 log CFU/g on days 21-28, so it became necessary to use VP or MAP to maintain these microorganisms at an acceptable level for the entire storage period. TVB-N contents were low in samples with additives, regardless of the kind of packaging, as well as in blanched samples packaged in VP and MAP, never reaching 25 mg/100 g. Since there were no significant differences either in microbial growth or in TVB-N between samples in VP and MAP, a sensory analysis was performed only in desalted cod submitted to the two treatments (blanching and additives) combined with VP, both in raw and cooked samples. The results of this analysis showed that the addition of potassium sorbate and citric acid did not alter the typical organoleptic features of desalted cod. The sensory characteristics of both blanched samples and those with additives in VP showed no change during the period of the study.     

Aroma changes in mango juice during processing and storage

Mango juice was analysed after bottling and during storage for 2 and 4 months, in order to follow the changes in aroma constitutents which have an adverse influence on the juice quality. Heat processing at 85°C/10 min caused the reduction of all volatile fractions due to evaporation and, in addition, the formation of acetyl furan, 5-methyl furfural, β-terpineol, terpinen-4-ol and butyl-3-hydroxy butanoate, which were not found in fresh juice. These compounds were attributable to degradation reactions and especially to ascorbic acid. Storage of bottled mango juice at room temperature resulted in the appearance of ethyl fatty acids and seline-11-ene-4-ol, in addition to a decrease in hydrocarbons and oxygenated components; these very important factors affected the flavour of mango juice.

According to these findings, the furan derivatives, - and β-terpineol, terpinen-4-ol and ethyl fatty acids, are detrimental factors resulting from heat-processing and storage of bottled mango juice.     

再制干酪贮藏期间的物理及化学变化

再制干酪往往被认为是一种保质期较长的、稳定的干酪食品。事实上，再制干酪即便不被微生物污染，室温下的保质期也只有几个月。贮藏期间，再制干酪的质地和风味都慢慢改变，本文阐述了引起储藏期间再制干酪质地和风味变化的主要原因，对引起这些变化的因素加以分析．并概括了国外关于再制干酪储藏期的研究进展。通过对再制干酪贮藏期质地变化的研究，将有助于干酪生产者更好的预测和控制产品贮藏期间的质量。     

Quality changes in pomegranates during ripening and cold storage

The changes in the quality parameters of Spanish pomegranate fruit (cultivar Mollar) during ripening and during 7 weeks of cold storage at 5°C and 90–95% relative humidity were studied. The fruit and seed weights, as well as the surface colour increased with ripening. Total soluble solids (TSS), pH and titratable acidity (TA) did not show significant differences during the weeks studied (from the 26th to 32nd weeks after flowering), but the seeds' colour (Lab values) and juice colour (absorbance at 510 nm) showed an increase during this period with a maximum during the last 2 weeks. These results indicate that pomegranates should be harvested during the 31st to the 32nd after flowering, in order to get the best pigmentation without a decrease in other quality parameters. The anthocyanin profile changed during the different maturity stages, since the diglucoside derivatives were the prevailing pigments during the early ripening stages, whereas the monoglucoside derivatives were the main pigments in the latter stages. After cold storage of pomegranates harvested at two maturity stages, no differences in TSS, pH, TA and skin colour were observed. In addition, seeds' and juice colour did not decrease during storage. Hence, this study supports the theory that pomegranate is a nonclimacteric fruit and that pomegranates can be stored for at least 45 days without deterioration in the fruit quality.     

酶解与均质对香蕉浆料稳定性的影响

对香蕉浆料进行单因素和正交实验,确定最佳酶解条件为果胶酶用量0.07%,淀粉酶用量0.03%,温度50℃,时间2h。通过不同均质处理后的流变性和静置稳定性的比较,得出香蕉浆料的最佳均质条件为20MPa,2次。     

Effect of rice bran protein extract on enzymatic browning inhibition in potato puree

Effect of rice bran protein extract (RBPE) on enzymatic browning inhibition in potato puree was studied by colour measurement and polyphenol oxidase (PPO) inhibition. RBPE inhibited browning in potato puree and showed a higher per cent potato PPO inhibition at pH 4.0 and 5.0 than those at pH 3.0, 6.0 and 7.0 (P ≤ 0.05). RBPE heated to 40 and 60 °C had browning inhibition in potato puree and per cent potato PPO inhibition at a similar extent to unheated RBPE (P > 0.05). Browning inhibition and per cent potato PPO inhibition of RBPE were decreased when it was heated to 80 °C (P ≤ 0.05). RBPE inhibited browning in potato puree higher than 5, 10 and 20 mm ascorbic acid and 5 and 10 mm citric acid (P ≤ 0.05). Regarding the kinetics study, RBPE exhibited a mixed‐type inhibition for potato PPO. Therefore, RBPE has a potential to be used as a natural antibrowning agent in the potato industry.