Survival,fermentation activity and storage stability of spray dried Lactococcus lactis produced via different atomization regimes

Dried powders containing Lactococcus lactis ssp. cremoris were produced using laboratory and pilot scale spray dryers with lactose:whey protein isolate (3:1) as a protective medium. The effects of storage temperature (25, 4 and −18 °C) and time (30, 60 and 90 days) were studied. The survival and fermentation activity of the dried bacterial cells were significantly lower when the powders were stored at 25 °C compared to those stored at 4 and −18 °C; powders stored at 4 and −18 °C were statistically similar. The survival and fermentation activity of bacterial cells obtained from a laboratory scale two-fluid nozzle spray dryer were found to be higher than those of cells obtained from a pilot scale two-fluid spray dryer. A rotary wheel atomizer gave significantly higher survival and activity in the same dryer. These observations are consistent with cell damage due to high characteristic shear rates in the atomization process in nozzle type atomizers. The presence of ascorbic acid (oxygen scavenger) in the powder composition was found to improve both the survival and the maintenance of fermentation activity of the dried bacterial cells significantly during storage. The survival and fermentation activity of dried bacterial cells in stored powders indicated that these parameters are system-specific and can be strongly affected by the storage temperature and presence or absence of antioxidant, and also by upstream processing conditions such as the mode of atomization and presence or absence of antioxidants in the dryer feed.     

Preparation and storage stability of dried salted mutton

Minced (8 or 18 mm plate) mutton with salt (25%) and sorbate (0·4%) was pressed into cakes about 11 cm in diameter and 3 cm high. The cakes were partially dried in an air oven at 40°C for 48 h to a water activity of about 0·75. The cakes were packed, either in vacuo or in air, and stored at 30 or 2°C for up to 60 days. Objective assessment of quality showed that these dried salted meats can be kept for up to 60 days at 30°C with little loss of textural or nutritional quality although some fading, due to haemoprotein breakdown, occurs. Packaging in vacuum, however, minimises this loss of colour and would be recommended for centralised manufacture prior to distribution in developing, tropical countries.     

负载虾青素淀粉纳米粒的表征与稳定性能研究

为了提高虾青素的稳定性,制备了淀粉接枝聚甲基丙烯酸甲酯纳米粒,然后采用透析法,将虾青素与纳米粒混合制成虾青素纳米粒。测定了淀粉及接枝共聚物的红外光谱、纳米粒的平均粒径、粒径分布、纳米粒形态,并以虾青素的丙酮溶液作为比较,对虾青素纳米粒的稳定性进行了测定。结果表明,虾青素纳米粒的平均粒径为(208.1±26.4)nm,分散系数为0.284±0.035;4 h光照后,虾青素纳米粒保留率为26.34%;30℃和50℃恒温避光下,贮存8 d时虾青素纳米粒的保留率分别为91.81%和83.44%;在p H=1、3、5、7、9或11条件下,虾青素纳米粒的保留率平均值为86.18%。      

Cryoprotective effects of trehalose and sodium lactate on tilapia (Sarotherodon nilotica) surimi during frozen storage

The cryoprotective effects of trehalose and sodium lactate at level of 8% (w/w) in tilapia surimi were studied in comparison with a conventional cryoprotectant (sucrose/sorbitol, 1:1) during extended storage at −18 °C for up to 24 weeks. All present cryoprotectants retarded the protein changes as evidenced by the lowered decrease in salt extractable protein (SEP), Ca²⁺-ATPase activity, total sulfhydryl content as well as the impeded increase in disulfide bond content and surface hydrophobicity. The gel-forming ability of frozen surimi was more retained with addition of cryoprotectants. Among all cryoprotectants used, trehalose exhibited the greatest protective effect on protein denaturation as shown by the effectiveness in maintaining Ca²⁺-ATPase activity and protein solubility. Additionally, the greatest breaking force and deformation were obtained in surimi added with 8% trehalose throughout the frozen storage up to 24 weeks. Sodium lactate showed a similar cryoprotective effect to sucrose/sorbitol blend. Therefore, trehalose and sodium lactate appeared to be promising alternative cryoprotectants for surimi owing to their low sweetness and caloric value.     

Chemical and microbial stability of high moisture dried apricots during storage

BACKGROUND: This study was conducted to determine the chemical and microbial stability of high moisture (HM) dried apricots during storage at 5, 20 and 30 °C for a period of 8 months. HM dried apricots were obtained by rehydrating dried apricots in ‘water’ and ‘water + H₂O₂’. RESULTS: Analysis of kinetic data suggested first‐order models for loss of SO₂ and non‐enzymatic browning reactions. Higher storage temperatures increased the rate of SO₂ loss and formation of brown colour in HM dried apricots. Results from extensive colour measurements (non‐enzymatic browning, reflectance colour and β‐carotene) revealed that the colour of HM dried apricots stored at 5 °C was almost unchanged during 8 months of storage. The colour of samples stored at 30 °C was unacceptable starting from 2 months of storage. Total mesophilic aerobic bacteria counts decreased 0.7, 1.1 and 1.5 log cycles after 8 months of storage at 5, 20 and 30 °C, respectively. For the same storage period, the decrease in mesophilic bacteria was 0.62 log cycle in samples rehydrated in ‘water + H₂O₂’ and stored at 20 °C. CONCLUSION: These results suggest that HM dried apricots should be stored at temperatures lower than 20 °C to preserve the characteristic golden yellow colour. A relatively low level of SO₂ (1458 mg kg^?1 at 200 g kg^?1 moisture level) was sufficient to prevent the growth of spoilage organisms in HM dried apricots at all three storage temperatures. Copyright © 2008 Society of Chemical Industry     

Effect of phospholipids on membrane characteristics and storage stability of liposomes

The membrane characteristics and storage stability of liposomes prepared by different phospholipids were investigated, including soybean phosphatidylcholine (SPC), egg yolk phosphatidylcholine (EPC) and hydrogenated soy phosphatidylcholine (HSPC). The mean vesicle size of HSPC liposomes was 437.8 nm, while the size of SPC and EPC liposomes were 112.3 and 121.3 nm, respectively. The AFM and TEM images demonstrated that SPC and EPC liposomes exhibited a more uniform distribution and greater membrane fluidity. The liposomes demonstrated different crystallization behavior and phase transition temperatures by XRD and DSC, respectively. Due to high saturated fatty acids content of HSPC, these liposomes displayed a tighter membrane packing as evident by FTIR and Raman spectra. The membrane hydrophobicity and micropolarity decreased with storage time. During storage, HSPC liposomes maintained a more compact membrane structure. HSPC liposomes were the most stable during storage as evident by significantly lower levels of lipid hydrolysis and oxidation.     

Characterization of volatile compounds in a fermented and dried fish product during cold storage

ABSTRACT:  The northern European production technique for dry-cured meat sausages was used to produce a sliceable, fermented, and dried fish product rich in omega-3 polyunsaturated fatty acids (PUFA). The fatty fish Atlantic salmon ( Salmo salar) , the lean fish saithe ( Pollachius virens ) (1:1, w/w), Lactobacillus sakei , and 4 different milk protein-based ingredients were used in the recipes. The changes in the volatile compounds during cold storage (+4 °C) of vacuum-packed dried sausages were studied by dynamic headspace gas chromatography-mass spectrometer (GC-MS). Of  the 117 volatile compounds identified, alcohols, alkanes, esters, aldehydes, ketones, and compounds derived from amino acids were the most prevalent groups of volatiles. Thirty volatiles decreased and 17 increased significantly ( P < 0.1) during storage for 15 wk. Despite the high content of PUFA, amino acid catabolism and ester synthesis led to larger changes in the composition of volatiles in the fish product than did lipid oxidation reactions. The milk-protein-based powders that were used to physically stabilize the fish oil did not affect the lipid oxidation compounds.     

Effect of anacardic acid on oxidative and color stability of spray dried egg yolk

The effect of anacardic acid on lipid stability and coloration of spray dried yolks was evaluated. The yolks were added to antioxidants, according to the treatments: no added antioxidant, with 100 mg/kg butylated hydroxytoluene and with 50, 100, 150 and 200 mg/kg anacardic acid. The yolks was dehydrated according to the following conditions: inlet temperature of drying air (130 °C), feed flow rate of yolk (0.5 L/h) flow of hot air (3,5 m³/min) and pressurized air flow (30 L/min). After drying, yolks were stored for 180 days, and the analysis of lipid oxidation and color performed each 45 days. In regression analysis to assess anacardic acid-dose effect, there was a linear decrease in lipid oxidation in all storage periods with the increased acid dose. According to the means test, at 0, 90, 135 and 180 days, the concentrations of 150 and 200 mg/kg anacardic acid were more effective in retarding the lipid oxidation. The anacardic acid inclusion provided higher yellowness in the yolks, which decreased linearly with storage. Thus, the dose of 150 mg/kg anacardic acid had the best results among treatments studied to prevent the damage of lipid oxidation in the yolk, favoring the coloring.     

Effect of spray drying and storage on the stability of bayberry polyphenols

Bayberry juice was spray dried with maltodextrin (DE 10) as a carrier and then stored under different temperature and water activities (aw). The retention of the total phenolic content (TPC) and total anthocaynins (ACN) during the drying process were about 96% and 94%, respectively, suggesting spray drying was a satisfactory technique for drying heat sensitive polyphenols. Under an aw of 0.11–0.44, the TPC and ACN in bayberry powders decreased by about 6–8% and 7–27%, respectively, after 6 months storage at 4 °C; at 25 °C for the same storage period the decreases were between 6–9% and 9–37%, respectively, while at 40 °C the decreases were in the range 7–37% and 9–94%. The anthocyanin component was more readily degraded relative to other phenolic compounds. The results suggest that bayberry powder should be stored at less than 25 °C and aw of 0.33, on account of greater polyphenol stability under such conditions.     

多重油脂微胶囊乳液喷雾干燥粉工艺及其理化性质

为提高膳食中脂肪酸组成多样性,本研究以多重脂肪酸组成的复合油脂（玉米油、黄油、椰子油、藻油）为芯材,麦芽糊精、乳清蛋白浓缩物、酪蛋白酸钠为主要壁材,通过微射流耦合食品乳化剂制得O/W型均匀乳液,经喷雾干燥制得粉末微胶囊,利用单因素实验结合响应面分析包埋率影响因素,优化了最佳制备工艺: 进风温度170 ℃、均质压力31 MPa、乳化剂添加量0.3%,该产品的油脂包埋率高达85.75%。红外光谱（FTIR）分析证实油脂通过微胶囊得到了较好包埋,扫描电镜（SEM）图像显示产品表面虽略有凹陷但是结构致密完整。实验发现产品粉末的复原乳液液滴平均粒径为241.8 nm,zeta电位为-33.1 mV,显示该产品具有良好的复溶性与稳定性;激光共聚焦扫描显微镜（CLSM）发现油脂完整包埋且可均匀悬浮,显示微胶囊复原乳中油脂的保护效果好。     

Colour stability of lutein esters in liquid and spray dried delivery systems based on Quillaja saponins

Aim of the present study was to expand the existing knowledge on the functionality of Quillaja saponin extract by comparing micellar systems, nanoemulsions and the corresponding spray-dried formulations for the delivery of lutein esters as colouring agents to foods. A chemically well-defined saponin extract was used, and characterised by MALDI-TOF-MS and HPTLC-MALDI-TOF-MS. The composition of the extract comprised all major saponins described for Quillaja, but the relation between the individual constituents differed considerably from the literature. Colour intensity of lutein ester loaded systems was higher in nanoemulsions compared to micelles. Quillaja saponins provided good stability to lutein ester loaded systems during the process of microencapsulation by spray drying, as indicated by particle size analysis of the dispersed phases and colour determination. Colour stability upon storage was high in microencapsulated formulations. Results therefore prove the high functionality of Quillaja saponins for stabilisation of sensitive, natural food colourants.     

Physicochemical properties and storage stability of spray‐dried soya bean sprout extract

Amylase is a very important enzyme due to its wide food applications. To preserve amylase activity in soya bean sprout extract (SSE), SSEs were spray‐dried with 10% maltodextrin and 0–3% alginic acids, and their physicochemical properties and storage stability were compared with freeze‐dried one. SSE exhibited maximum amylase activity at pH 7.0 and 60 °C, with the most active substrate specificity towards soluble starch. Spray‐dried SSEs exhibited higher water solubility index (WSI) and in vitro relative amylase activity but lower water vapour sorption (WVS) and smaller particle size than freeze‐dried SSE. For spray‐dried SSEs, particle size, WSI and in vitro relative amylase activity increased while WVS decreased with increasing % alginic acid. This study demonstrated that spray drying of SSE, especially with 10% maltodextrin and 2% alginic acid, was effective in keeping amylase active and stable during 7‐week storage at room temperature (25 °C).     

过热蒸汽对燕麦挂面贮藏稳定性及风味的影响

本文采用过热蒸汽钝化燕麦中脂质降解酶,并通过测定脂肪酸组成、脂肪酸值、生育酚和挥发性风味成分的变化来分析其对燕麦挂面贮藏稳定性的影响。结果表明,过热蒸汽处理后燕麦挂面中脂肪酶和过氧化物酶活性显著（p < 0.05）降低,脂肪氧合酶活性在贮藏后期显著下降。处理后的挂面脂肪酸值显著（p < 0.05）低于对照组,且贮藏12周后,190 ℃处理组中不饱和脂肪酸降解程度最低。同时,190 ℃处理组挂面贮藏期间生育酚的稳定性显著（p < 0.05）提升。GC-MS结果表明,己酸、2-戊基呋喃是燕麦挂面贮藏期间所产生的主要挥发性风味物质,而170、190 ℃处理可明显抑制其产生。综上,190 ℃过热蒸汽处理对提高燕麦挂面贮藏稳定性、改善风味有积极作用。     

双酶法制备牡蛎干酶解液及其体外抗氧化活性评价

以牡蛎干为原料,选用动物蛋白水解酶和风味蛋白酶对其进行酶解,获取营养丰富的蛋白酶解物。以水解度为试验指标,分别进行了酶解单因素及正交优化试验,结果表明最佳酶解工艺组合为:酶解时间5h,料液比1∶15(g/mL),加酶量3%。该条件下牡蛎干蛋白水解度为33.7%,蛋白质回收率为78.75%,酶解液中氨基酸总量达3 662.53mg/100mL,其中必需氨基酸含量达38.93%。对牡蛎干蛋白酶解物进行体外抗氧化活性评价,结果表明:该牡蛎干蛋白酶解物清除率DPPH自由基IC50为5.95mg/mL,清除ABTS自由基的IC50为10.8mg/mL,清除羟基自由基的IC50为14.56mg/mL。     

Production and properties of casein hydrolysate microencapsulated by spray drying with soybean protein isolate

The aim of this work was to encapsulate casein hydrolysate by spray drying with soybean protein isolate (SPI) as wall material to attenuate the bitter taste of that product. Two treatments were prepared: both with 12 g/100 g solids and containing either two proportions of SPI: hydrolysate (70:30 and 80:20), called M1 and M2, respectively. The samples were evaluated for morphological characteristics (SEM), particle size, hygroscopicity, solubility, hydrophobicity, thermal behavior and bitter taste with a trained sensory panel using a paired-comparison test (non-encapsulated samples vs. encapsulated samples). Microcapsules had a continuous wall, many concavities, and no porosity. Treatments M1 and M2 presented average particle sizes of 11.32 and 9.18 μm, respectively. The wall material and/or the microencapsulation raised the hygroscopicity of the hydrolysate since the free hydrolysate had hygroscopicity of 53 g of water/100 g of solids and M1 and M2 had 106.99 and 102.19 g of water/100 g of solids, respectively. However, the hydrophobicity decreases, the absence of a peak in encapsulated hydrolysates, and the results of the panel sensory test considering the encapsulated samples less bitter (p < 0.05) than the non-encapsulated, showed that spray drying with SPI was an efficient method for microencapsulation and attenuation of the bitter taste of the casein hydrolysate.     

肠溶包衣乳糖酶纳米微囊的制备及稳定性研究

研制一种在胃和肠液中对乳糖酶具有保护作用的口服制剂。采用复乳法制备了肠溶包衣乳糖酶纳米微囊,对其理化性质进行了评价;研究了制备过程中影响乳糖酶活性的主要因素,并采取了一定的保护策略;对微囊化的乳糖酶在人工胃液和人工肠液中的稳定性进行了考察。结果表明,超声强度越大,活性损失越多;在二氯甲烷中引入乙酸乙酯(体积比为1∶1),复乳化采用高压均质,有利于保护乳糖酶的活性。在内水相添加牛血清白蛋白、聚乙烯醇和聚乙二醇400等保护剂,可有效提高乳糖酶的活性。制备的肠溶包衣乳糖酶纳米微囊在人工胃液中2h乳糖酶剩余活性为88.97%,在含胰酶的人工肠液中6h,其活性保留可达95%以上,有望成为乳糖酶口服制剂的有效剂型。     

带骨兔肉脯的加工与贮藏

将兔骨制成食用骨粉,兔肉斩成肉糜,制成带骨兔肉脯。采用4因素3水平正交试验筛选出了带骨兔肉脯较优配方。并进行了带骨兔肉脯的辐射处理等贮藏试验。     

Cis-trans isomerisation of lycopene and colour stability of foam—mat dried tomato powder during storage

Tomato powder with ～3% moisture was obtained by foam-mat drying tomato paste (29% solids). Samples of powder were stored at various temperatures (?10° +2° +20° and +37°c), atmospheres (air, nitrogen) and humidities (with and without in-package desiccation), and colour changes were observed for periods of up to 1 year. The main cause of colour fading was the oxidation of lycopene. However, another phenomenon, trans—cis isomerisation of all-trans lycopene, can occur, with apparent loss of coloration, which is later restored by re-isomerisation. The existence of this mechanism was demonstrated by simultaneous measurements of total liposoluble colour at 420 nm and separations of carotenoid pigments by column chromatography on Al₂O₃. Neo-lycopene A (6-mono-cis-lycopene) and at least one other cis-lycopene isomer were found in fresh powder and in samples stored up to 5 months. cis-Isomers were more susceptible to oxidation. Colour changes depend upon the interplay of isomerisation and oxidation; in some cases, tomato powder was more intensively coloured after storage than when fresh. Storage at +20°c was more favourable for colour retention than storage at +2°c, or — 10°c. Excessive desiccation strongly promoted oxidation losses. Storage in an inert atmosphere improved colour retention. At +37°c non-enzymic browning, accompanied by formation of water, caused rapid darkening although carotenoid pigments were not lost to a great extent.     

Impact of trehalose,sucrose and/or maltodextrin addition on aroma retention in freeze dried strawberry puree

Trehalose was studied as a drying aid to establish its impact on aroma retention in freeze dried strawberry puree. The evaluation was done by sensory analysis and headspace‐solid phase microextraction‐gas chromatography with a mass detector (HS‐SPME‐GC‐MS); results were compared with those obtained using sucrose and maltodextrin (MD) as drying aids. The carbohydrate used significantly modified the type and concentration of volatiles retained during freeze drying. HS‐SPME‐GC‐MS outcomes showed that the use of trehalose (alone or with MD) resulted in the product with the chromatographic profile most similar to fresh strawberry puree, being different from sucrose and MD. Meanwhile, sensory analysis showed a similarity with the aromatic profiles when using trehalose or sucrose, remaining both different from MD. This study proved that the use of trehalose as a drying aid can be beneficial on volatile aroma retention and that different combinations of organic volatiles can lead to similar sensory profiles.