Effect of Processing and Storage Conditions on the Fate of Vitamins B1, B2, and C and on the Shelf-Life of Goat's Milk

Goat's milk was heat-processed under different time-temperature conditions of pasteurization and sterilization. Losses of thiamin, riboflavin, and total vitamin C in HTST, Flash, and UHT were less than that by LTLT and Autoclave. Also residual oxygen in the milk affected the loss of total vitamin C during storage. A longer shelf-life of pasteurized milk was obtained with HTST, HTST overpasteurization, and Flash process; however, there was no significant difference between UHT and Autoclave sterilized products. From the above results, HTST pasteurization was considered the best process to preserve milk quality.     

Effects of extrusion and conventional processing methods on protein and antinutritional factor contents in pea seeds

The effects of high temperature short time (HTST) treatment compared with other conventional processes on protein, phytic acid, condensed tannins, polyphenols, trypsin, chymotrypsin and α-amylase inhibitor activities and haemagglutinating activities in Renata, Solara and Ballet pea seeds were investigated. Ballet cultivar showed highest protein, phytic acid, tannin, polyphenol contents and trypsin and chymotrypsin inhibitory activities. All pea cultivars contained trypsin- and chymotrypsin-inhibiting activity and lectins but only Solara had α-amylase inhibitory activity. Under extrusion conditions (148°C, 25% moisture and 100 rpm) this thermal processing method was the most effective in condensed tannin, trypsin, chymotrypsin, α-amylase inhibitors and haemagglutinating activity reduction, without modifying protein content as occurs by dehulling, soaking and germination treatments. Trypsin and chymotrypsin inhibitors and haemagglutinating activities in peas were more readily abolished by extrusion treatment than was chymotrypsin inhibitory activity.     

Effect of Ultrafiltration Combined with High-Pressure Processing on Safety and Quality Features of Fresh Apple Juice

Ultrafiltration (UF, 0.05 μm) with a ceramic membrane was combined with high-pressure processing (HPP) at 500 MPa/6 min and high-temperature short time (HTST) at 110 °C/8.6 s to process fresh apple juice. The aim of this study was to compare the effect of UF + HPP and UF + HTST on quality features of fresh apple juice and analyze the quality changes of the juice treated by UF + HPP and stored during 60 days at 4 °C. Applying UF, total plate count (TPC) and yeasts and molds (Y&M) significantly decreased by 0.29 and 0.28 log cycle, total phenols and ascorbic acid decreased by 33.50 and 26.52 %, and antioxidant capacity, using the DPPH and FRAP assay, significantly decreased by 26.40 and 25.37 %. Meanwhile, the juice clarity was 99.75?±?0.07 % and seven aroma compounds were changed. TPC and Y&M in juices treated by UF + HPP and UF + HTST were <1 log cycle. When compared to the juice treated by UF + HTST, the juice treated by UF + HPP showed lower browning degree and higher total phenols and clarity, and retained seven main volatile aroma compounds. Fresh apple juice processed by UF + HPP was microbiologically safe (TPC <1.8 log cycles and Y&M <1 log cycle) during 60 days of storage at 4 °C. The first-order model was a suitable model for all quality parameters of refrigerated fresh apple juice; however, rate constant k of first-order model was between ?0.0157 and 0.0350, showing the quality features of the refrigerated juice was stable.     

INFLUENCE OF WOUND INJURY ON ACCUMULATION OF PROTEINASE INHIBITORS IN LEAF AND STEM TISSUES OF TWO PROCESSING TOMATO CULTIVARS

Serine proteinase inhibitor(s) and small amounts of cysteine proteinase inhibitor were detected in both leaf and stem tissue 48 h after mechanical injury to the lower leaf of 21–25 day old tomato cultivars (cv). Leaves accumulated about 2–15 times more trypsin inhibitor than stem tissue. Approximately 10 times more trypsin inhibitor (TIU) accumulated in plants held at 30C in continuous light compared to plants held under ambient greenhouse conditions after injury. Uninjured plants held at 30C under continuous light accumulated less proteinase inhibitor(s) than injured plants. Holding Bonnie Best in the dark at 30C for 48 h resulted in less inhibitor(s) accumulation in response to mechanical wounding than holding plants at 30C in continuous light. TIU/g tissue recovered from injured plants held at 30C under continuous light varied with cultivar, i.e., for leaves: Bonnie Best (33.61), Alta (21.00; 25.43), Castlemart (16.00; 13.17) and Halley (1.96); and for stems: Castlemart (8.29), Alta (4.47) and Bonnie Best (2.59). SDS-PAGE assayed for inhibitor activity revealed the main trypsin and chymotrypsin inhibitor(s) in injured leaves both had a molecular mass (Mr) of 19.1 KD on SDS-PAGE substrate gels. Treatment of the inhibitors with 2.0% SDS at 100C prior to electrophoresis revealed a second major trypsin inhibitor (Mr = 16.4 KD) and two additional major α-chymotrypsin inhibitors (Mr = 16.4; 6.2 KD).     

基于计算流体动力学技术的橙汁高温短时灭菌工艺优化

为对果汁高温短时灭菌工艺进行精确研究,在确保果汁品质时降低生产中的能耗,对罐装橙汁的超高温短时灭菌进行计算,分析果汁中常见的细菌,得出灭菌所需的最低温度,在此基础上,利用计算流体动力学(CFD)技术对橙汁的高温短时灭菌方式进行模拟实验,探讨不同温度条件下的灭菌最理想时间条件。结果表明：120℃(393K)、12min,125℃(398K)、11min,130℃(403K)、8min,135℃(408K)、7min 为最理想时间条件;同时根据卡诺循环,计算高温短时灭菌的能耗,得到单位质量橙汁灭菌的机械耗功率分别为127、150、217、263W。根据能耗最低的原则可以得到计算的灭菌温度范围中,最优灭菌工艺为120℃(393K)、12min。     

Impact of different pasteurization temperatures on the survival of microbial contaminants isolated from pasteurized milk

The thermal inactivation of selected microbes was studied using the low temperature long time (LTLT), high temperature short time (HTST) and 'pot' pasteurization methods. Survivors were enumerated after heating for up to 40 min for the LTLT and HTST pasteurization methods and after heating for up to 30 min for the 'pot' pasteurization method. With the exception of the Bacillus cereus strain, the selected microbes did not survive the LTLT and HTST pasteurization methods. The results from the 'pot' pasteurizer showed that B. cereus, Chryseobacterium meningosepticum, Pseudomonas putida, Acinetobacter baumannii and Escherichia coli strains survived the pasteurization conditions applied, showing that the 'pot' pasteurizer does not pasteurize effectively.     

Effect of Infrared Blanching on Enzyme Activity and Retention of β‐Carotene and Vitamin C in Dried Mango

The objectives of this work were to evaluate infrared (IR) dry blanching in comparison with conventional water blanching prior to hot air drying of mango to inactivate polyphenol oxidase (PPO) and ascorbic acid oxidase (AAO) enzymes, and to study its effect on color change and retention of vitamin C and β‐carotene. Mango cylinders were blanched under similar temperature–time conditions either by IR heating or by immersion in a water bath during 2 min at 90 °C (high‐temperature‐short‐time—HTST) or for 10 min at 65 °C (low‐temperature‐long‐time—LTLT). After blanching mango was hot air dried at 70 °C. PPO was completely inactivated during the blanching treatments, but AAO had a moderate remaining activity after LTLT treatment (～30%) and a low remaining activity after HTST treatment (9% to 15%). A higher retention of vitamin C was observed in mango subjected to IR dry blanching, 88.3 ± 1.0% (HTST) and 69.2 ± 2.9% (LTLT), compared with water blanching, 61.4 ± 5.3% (HTST) and 50.7 ± 9.6% (LTLT). All‐trans‐β‐carotene retention was significantly higher in water blanched dried mango, 93.2 ± 5.2% (LTLT) and 91.4 ± 5.1% (HTST), compared with IR dry blanched, 73.6 ± 3.6% (LTLT) and 76.9 ± 2.9% (HTST). Increased levels of 13‐cis‐β‐carotene isomer were detected only in IR dry blanched mango, and the corresponding dried mango also had a slightly darker color. IR blanching of mango prior to drying can improve the retention of vitamin C, but not the retention of carotenoids, which showed to be more dependent on the temperature than the blanching process. A reduction of drying time was observed in LTLT IR‐blanching mango.     

Comparison of Microbial Inactivation and Rheological Characteristics of Mango Pulp after High Hydrostatic Pressure Treatment and High Temperature Short Time Treatment

The effects of high hydrostatic pressure (HHP) treatments at pressures of 300–600 MPa for 1–20 min and of high-temperature, short-time (HTST) treatment on the inactivation of natural microorganisms in blanched mango pulp (BMP) and unblanched mango pulp (UBMP) were investigated. No yeasts, molds, or aerobic bacteria were detected in BMP or UBMP after HHP treatments at 300 MPa/15 min, 400 MPa/5 min, 500 MPa/2.5 min, and 600 MPa/1 min and HTST treatment at 110 °C/8.6 s. Therefore, these conditions were selected to study the effects of HHP and HTST treatments on pectin methylesterase (PME) activity, water-soluble pectin (WSP) levels, and the rheological characteristics of UBMP and BMP. HHP treatment at a pressure of 600 MPa for 1 min significantly reduced PME activity in UBMP and significantly activated PME in BMP, whereas pressures of 300–500 MPa activated PME regardless of blanching. However, PME activity was reduced by 97 % in UBMP and was completely inactivated in BMP by HTST treatment. WSP levels were significantly decreased by HHP treatment but were increased by HTST treatment in UBMP and BMP. Both HHP and HTST treatments increased the viscosity, storage modulus, and loss modulus of UBMP and BMP. No significant changes in total sugar, total soluble solids, titratable acid, or pH were found after any treatment.     

Potentiation of fungicidal activities of trans-anethole against Saccharomyces cerevisiae under hypoxic conditions

A naturally occurring phenylpropanoid, trans-anethole (anethole), was assayed for its fungicidal activity in Saccharomyces cerevisiae grown under hypoxic and aerobic conditions. Anethole killed the growing cells in malt extract broth only under hypoxic conditions. Anethole did not exhibit fungicidal effects against non-growing cells. The cells of a mitochondrial-DNA-lacking rho0 mutant, which grew fermentatively even in the presence of O2, were killed by anethole regardless of aeration. The fungicidal potency of anethole against a strain capable of respiration under aerobic conditions was enhanced by the addition of a respiratory inhibitor antimycin A3. Therefore, anethole possibly expresses fungicidal activities only against fermentatively growing cells of S. cerevisiae.     

Development of quick-cooking dehydrated pulses by high temperature short time pneumatic drying

Quick-cooking dehydrated pulses were made from husked split grains of red gram, black gram and Bengal gram using high temperature short time (HTST) pneumatic drying technique wherein porosity was brought about in the dried pulses by exposure of the cooked grains initially to air at a high temperature (170–200°C) for a short duration (4–6 min) in a laboratory model HTST pneumatic drier followed by finish drying at a lower temperature (60–70°C) in a conventional tray or fluidized bed drier. Optimum temperature and time for the HTST drying of the grains were worked out and the HTST dried products were evaluated with respect to their drying behaviour, rehydration characteristics and shelf stability vis-a-vis the conventional hot air dried products.
Considerable reduction in drying and rehydration times could be achieved by the HTST process. The increase in porosity achieved and the HTST treatment did not adversely affect the shelf stability of the grains to any measurable extent.
The technique involves simple equipment and less capital investment as compared to other methods of drying, such as explosive puffing, achieving the same objective. It is amenable to continuous processing as the time of high temperature drying is very short.     

Canned Dry Bean Quality as Influenced by High Temperature Short Time (HIST) Steam Blanching

High temperature short time (HTST) steam blanched dry beans had greater drained weights and shear values than water blanched dry beans. Moisture content of dry beans was greater after water blanching. Subjective grade was closely related to drained weights and shear values, and HTST steam blanched dry beans had better subjective grades than water blanched dry beans. Water blanched dry beans were lighter in color than HTST steam blanched dry beans. As length of HTST steam blanch was increased, Agtron color of the beans darkened. High quality canned dry beans can be produced with HTST steam blanching with energy and time savings, but differences between water and HTST steam blanching and canning quality is highly dependent on cultivar and length of HTST steam blanch.     

Quality of applesauces processed by pulsed electric fields and HTST pasteurisation†

A pilot plant scale continuous flow pulsed electric field (PEF) and high temperature short time (HTST) processing system was integrated with an aseptic packaging machine. Fuji applesauce and blueberry applesauce were processed with PEF followed by HTST pasteurisation (PEF + HTST). PEF + HTST processed Fuji applesauce from fresh Fuji apples demonstrated high and stable sensory scores during 9 months storage at 27 °C, and had comparative sensory quality with Meal Read‐to‐Eat (MRE) and commercial applesauce products stored at 4 °C. PEF + HTST processed blueberry applesauce from pre‐pasteurised materials had lower sensory scores than PEF + HTST processed Fuji applesauce and was significantly less stable during the storage at 27 °C. PEF + HTST processed applesauces had aerobic count and mould and yeast count of <10 cfu mL^?1 during storage. Electrical conductivity, pH and °Brix, were not significantly changed throughout storage time (P > 0.05).     

鲜食青花椒热处理工艺

为了延长青花椒的贮藏期,以汉源青花椒为实验材料,采用高温蒸汽短时热处理方法,以挥发油含量和过氧化物酶(POD)酶活为指标,在研究蒸汽压力、蒸汽处理时间和载料量单因素试验基础上,进行Box-Behnken中心组合试验,利用响应面分析优化的最佳热处理工艺条件为蒸汽压力0.33MPa、蒸汽处理时间12.4s、载料量2696g/m2,在此条件下响应面模型预测的挥发油含量为0.41mL/20g。     

Effect of HTST Pasteurization of Milk, Cheese Whey and Cheese Whey UF Retentate upon the Composition, Physicochemical and Functional Properties of Whey Protein Concentrates

The effect of high temperature-short time (HTST) pasteurization of milk, Cheddar cheese whey and cheddar cheese whey ultrafiltration (UF) retentate upon the composition, physicochemical and functional properties of whey protein concentrates (WPC) was investigated. HTST pasteurization (72°C-15 sec) of milk, whey and UF retentate caused no significant differences in chemical composition of resulting WPCs. HTST pasteurization of milk and whey had no significant effect upon WPC solubility, whereas, heating UF retentate caused significant loss of WPC solubility. HTST pasteurization of milk caused a significant lowering (P<0.10) of maximum foam expansion of WPC dispersions, but HTST pasteurization of whey and UF retentate had no significant effect upon this latter parameter.     

Effects of pulsed electric field on colloidal properties and storage stability of carrot juice

The effects of pulsed electric fields (PEF) and high‐temperature short time (HTST) on the colloidal properties of carrot juice initially after PEF processing and throughout storage period were studied. Compared with HTST treatments, PEF treatments have less effect on the colloidal properties, such as cloud stability, zeta potential, viscosity and particle size distribution (PSD). Pectin methyl esterase (PME) could influence the colloidal properties of carrot juice by de‐esterification of the pectin. In the present work, PME activity was reduced significantly as electric‐field strength (from 15 to 30 kV cm^?1) and treatment time (from 100 to 800 μs) increased. The results also showed that the emergency of a new peak in PSD of samples occurred when the electric intensity exceeded 30 kV cm^?1. Images of transmission electron microscopy showed that particles slightly gathered after PEF treatment. However, under HTST treated, these smaller particles aggregated into net‐like structures that further gathered larger particles. At the micro level, both PEF treated (30 kV cm^?1, 800μs) and HTST treated kept good stability for more than 1 month.     

HlGt-i TEMPERATURE-SHORT TIME (HTST) PROCESSING OF SUSPENSIONS CONTAINING BACTERIAL SPORES

HTST sterilization of nutrient broth containing particles inoculated with B. subtilis 5230 spores was evaluated. The particles were tight rolls of chromatography paper 12.7 mm long by 7.64 mm in diam. Presence of these particles increased the time needed to sterilize the broth. These results are quantitatively presented as a protection ratio. For nutrient broth containing paper rolls, the protection ratio was of no concern at a processing temperature of 240° F, began to become important at 250° F and became the dominant factor at 260° F and above. It is thus established that the time of a HTST process of liquids containing particles differs significantly from HTST processing of clear liquids. For example, this difference should apply to commercial HTST processing of meat in a gravy stew or dumplings in a chicken soup as contrasted with consommes or to fermentation mashes as compared to fermentation broths.     

Frozen Vegetable Quality as Influenced by High Temperature Short Time (HTST) Steam Blanching

Quality differences in processed vegetables can be controlled with high pressure steam blanching (HTST). In addition, HTST blanching required significantly less energy to blanch vegetables than water blanching. HTST-blanched vegetables displayed quality parameters distinctly different than water-blanched vegetables. Differences in quality parameters were highly dependent upon the vegetable being blanched and the pressure and time of the HTST blanch. The quality of vegetables were similar between water and HTST blanching treatments, but by controlling the pressure and time of the HTST blanch, quality characteristics could be changed to meet individual requirements. High quality frozen vegetables can be produced with HTST steam blanching but quality is dependent upon the particular vegetable and pressure and time of the HTST steam blanch.     

Flow characteristics of a pilot-scale high temperature, short time pasteurizer

In this study, we present a method for determining the fastest moving particle (FMP) and residence time distribution (RTD) in a pilot-scale high temperature, short time (HTST) pasteurizer to ensure that laboratory or pilot-scale HTST apparatus meets the Pasteurized Milk Ordinance standards for pasteurization of milk and can be used for obtaining thermal inactivation data. The overall dimensions of the plate in the pasteurizer were 75 x 115 mm, with a thickness of 0.5 mm and effective diameter of 3.0 mm. The pasteurizer was equipped with nominal 21.5- and 52.2-s hold tubes, and flow capacity was variable from 0 to 20 L/h.Tracer studies were used to determine FMP times and RTD data to establish flow characteristics. Using brine milk as tracer, the FMP time for the short holding section was 18.6 s and for the long holding section was 36 s at 72 degrees C, compared with the nominal times of 21.5 and 52.2 s, respectively. The RTD study indicates that the short hold section was 45% back mixed and 55% plug flow for whole milk at 72 degrees C. The long hold section was 91% plug and 9% back mixed for whole milk at 72 degrees C. This study demonstrates that continuous laboratory and pilot-scale pasteurizers may be used to study inactivation of microorganisms only if the flow conditions in the holding tube are established for comparison with commercial HTST systems.     

UHP与HTST杀菌处理的猕猴桃NFC果汁贮藏期品质变化

通过比较不同杀菌处理(超高压 Ultra-high pressure,UHP和高温短时 High temperature short-time,HTST)的猕猴桃非浓缩还原汁(Not From Concentrate,NFC)贮藏期(4 ℃,4周)品质的变化,为明确NFC果汁产品杀菌方式提供理论依据。以海沃德猕猴桃为原料制备NFC果汁,利用化学、微生物学等方法及GC-MS手段研究了两种杀菌处理(UHP,400 MPa,15 min;HTST,95 ℃,30 s)的NFC猕猴桃汁贮藏期的理化与营养、微生物、抗氧化活性及香气物质的变化。结果表明,UHP与HTST杀菌的NFC果汁V_C与总糖含量分别减少为14.89%、18.96%和16.03%、18.62%;UHP处理贮藏期果汁的pH、可溶性固形物、总酸含量变化均较小,HTST杀菌的NFC猕猴桃果汁变色大于UHP。UHP与HTST处理的NFC果汁均有100%杀菌率,但贮藏期HTST杀菌NFC果汁微生物指标好于UHP处理。贮藏期UHP与HTST处理NFC果汁对DPPH、ABTS自由基的清除率下降,第4周分别为79%和74%、78%和74%。UHP处理后NFC果汁香气物质中醇类和酯类的种类和含量(4.75%,2.53%)降低,酮类和醛类物质的种类和含量(6.10%,27.38%)增加;HTST处理后醇类物质含量降低5.14%,种类增加;酮类、醛类物质的种类和含量(8.14%,26.39%)增加。试验说明UHP处理的猕猴桃NFC果汁在4 ℃贮藏3周其色泽、营养、香气与抗氧化活性的保留率高于HTST杀菌,最大限度地保持猕猴桃NFC果汁品质;该研究结果可为NFC果汁生产与货架期的确定提供试验依据。