Ready-to-drink protein beverages: Effects of milk protein concentration and type on flavor

This study evaluated the role of protein concentration and milk protein ingredient [serum protein isolate (SPI), micellar casein concentrate (MCC), or milk protein concentrate (MPC)] on sensory properties of vanilla ready-to-drink (RTD) protein beverages. The RTD beverages were manufactured from 5 different liquid milk protein blends: 100% MCC, 100% MPC, 18:82 SPI:MCC, 50:50 SPI:MCC, and 50:50 SPI:MPC, at 2 different protein concentrations: 6.3% and 10.5% (wt/wt) protein (15 or 25 g of protein per 237 mL) with 0.5% (wt/wt) fat and 0.7% (wt/wt) lactose. Dipotassium phosphate, carrageenan, cellulose gum, sucralose, and vanilla flavor were included. Blended beverages were preheated to 60°C, homogenized (20.7 MPa), and cooled to 8°C. The beverages were then preheated to 90°C and ultrapasteurized (141°C, 3 s) by direct steam injection followed by vacuum cooling to 86°C and homogenized again (17.2 MPa first stage, 3.5 MPa second stage). Beverages were cooled to 8°C, filled into sanitized bottles, and stored at 4°C. Initial testing of RTD beverages included proximate analyses and aerobic plate count and coliform count. Volatile sulfur compounds and sensory properties were evaluated through 8-wk storage at 4°C. Astringency and sensory viscosity were higher and vanillin flavor was lower in beverages containing 10.5% protein compared with 6.3% protein, and sulfur/eggy flavor, astringency, and viscosity were higher, and sweet aromatic/vanillin flavor was lower in beverages with higher serum protein as a percentage of true protein within each protein content. Volatile compound analysis of headspace vanillin and sulfur compounds was consistent with sensory results: beverages with 50% serum protein as a percentage of true protein and 10.5% protein had the highest concentrations of sulfur volatiles and lower vanillin compared with other beverages. Sulfur volatiles and vanillin, as well as sulfur/eggy and sweet aromatic/vanillin flavors, decreased in all beverages with storage time. These results will enable manufacturers to select or optimize protein blends to better formulate RTD beverages to provide consumers with a protein beverage with high protein content and desired flavor and functional properties.     

Effect of dipotassium phosphate and heat on milk protein beverage viscosity and color

Our objective was to determine the effect of addition of dipotassium phosphate (DKP) at 3 different thermal treatments on color, viscosity, and sensory properties of 7.5% milk protein-based beverages during 15 d of storage at 4°C. Micellar casein concentrate (MCC) and milk protein concentrate (MPC) containing about 7.5% protein were produced from pasteurized skim milk using a 3×, 3-stage ceramic microfiltration process and a 3×, 3-stage polymeric ultrafiltration membrane process, respectively. The MCC and MPC were each split into 6 batches, based on thermal process and addition of DKP. The 6 batches were no postfiltration heat treatment with added DKP (0.15%), no postfiltration heat without added DKP (0%), postfiltration high-temperature, short time (HTST) with DKP, postfiltration HTST without DKP, postfiltration direct steam injection with DKP, and postfiltration direct steam injection without DKP. The 6 MCC milk-based beverages and the 6 MPC milk-based beverages were stored at 4°C. Viscosity, color, and sensory properties were determined over 15 d of refrigerated storage. MCC- and MPC-based beverages at 7.5% protein with and without 0.15% added dipotassium phosphate were successfully run through an HTST and direct steam injection thermal process. The 7.5% protein MCC-based beverage contained a higher calcium and phosphorus content (2,425 and 1,583 mg/L, respectively) than the 7.5% protein MPC-based beverages (2,141 and 1,338 mg/L, respectively). Pasteurization (HTST) had very little effect on beverage particle size distribution, whereas direct steam injection thermal processing produced protein aggregates with medians in the range of 10 and 175 μm for MPC beverages. A population of casein micelles at about 0.15 μm was found in both MCC- and MPC-based beverages. Larger particles in the 175-μm range were not detected in the MCC beverages. In general, the apparent viscosity (AV) of MCC beverages was higher than MPC beverages. Added DKP increased the AV of both MCC- and MPC-based beverages, while increasing heat treatment decreased AV. The AV of beverages with DKP increased during 15 d of 4°C of storage for both MCC and MPC, whereas there was very little change in AV during storage without DKP and a similar effect was observed for sensory viscosity scores. The L value of beverages was higher with higher heat treatment, but DKP addition decreased L value and sensory opacity greatly. Sulfur-eggy flavors were detected in MPC beverages, but not MCC-based beverages.     

A Comparison of the Stability of Beverage Cloud Emulsions Formulated with Different Gum Acacia- and Starch-Based Emulsifiers

Abstract: The performance of several hydrocolloids (3 gum acacias, 1 modified gum acacia, and 3 modified starches) in stabilizing beverage emulsions and corresponding model beverages was investigated employing different core materials, emulsifier usage levels, and storage temperatures. Concentrated emulsions were prepared using orange terpenes or Miglyol^® 812 (comprising medium-chain triglycerides, MCT) weighted 1:1 with ester gum, stored at 25 or 35 °C, and analyzed on days 0, 1, and 3. On day 3, model beverages were made from each emulsion, stored at both temperatures, and analyzed weekly for 4 wk. Stability of concentrated emulsions was assessed by measuring mean particle size and by visual observations of ringing; beverage stability was judged similarly and also by loss of turbidity. Particle size measurements showed concentrated emulsions containing gum acacia or modified gum acacia with either core material were stable over 3 d storage at both temperatures whereas those made with modified starches were not, destabilization being faster at 35 °C. Beverages based on orange terpenes, in contrast to Miglyol, yielded smaller mean particle sizes, both on manufacture and during storage, regardless of hydrocolloid used. Visual observations of ringing generally supported this finding. Modified gum acacia was evaluated at both recommended and higher usage levels, stability increasing in the latter case. In general, all gum acacia and modified gum acacia emulsifiers were superior in stability to those based on modified starches, at either temperature, for orange terpene-based beverages. In Miglyol-based beverages, similar results were seen, except 1 modified starch performed as well as the gum acacia products.     

Nutritional, Microbiological, and Sensory Qualities of a Peanut Beverage Prepared Using Various Processes

Nutritional, microbiological and sensory qualities of peanut beverages processed at 85°C, 100°C and 121°C for 15 min and 121°C for 3 sec were determined. Heating improved the digestibility of peanut beverages, particularly those processed at 121°C for 3 sec and 85°C for 15 min. Methionine was particularly sensitive to the treatment at 121°C. The limiting amino acids were threonine, cystine, valine, lysine and tyrosine. No microbial growth was observed in products processed at 100°C and 121°C followed by storage at 4°C and 30°C for 20 days. Beverage processed at 85°C and stored at 30°C for 3 days contained an aerobic microbial population of 2.4 × 10⁴ CFU/mL. The beany flavor was least pronounced in beverages processed at 100°C for 15 min and strongest at 121°C for 3 sec.     

Influence of milk protein concentrates with modified calcium content on enteral dairy beverage formulations: Storage stability

Control of calcium-mediated storage defects, such as age gelation and sedimentation, were evaluated in enteral high-protein dairy beverages during storage. To investigate the effects of reduced-calcium ingredients on storage stability, 2 batches each of milk protein concentrates (MPC) with 3 levels of calcium content were acquired [control, 20% calcium-reduced (MPC-20), and 30% calcium-reduced (MPC-30)]. Control and calcium-reduced MPC were used to formulate 8% (wt/wt) protein enteral dairy beverages. The formulation also consisted of other ingredients, such as gums, maltodextrin, potassium citrate, and sucrose. The pH-adjusted formulation was divided into 2 parts, one with 0.15% sodium hexametaphosphate (SHMP) and the other with 0% SHMP. The formulations were homogenized and retort sterilized at 121°C for 15 min. The retort-sterilized beverages were stored at room temperature for up to 90 d and particle size and apparent viscosity were measured on d 0, 7, 30, 60, and 90. Beverages formulated using control MPC with 0 and 0.15% SHMP exhibited sedimentation, causing a decrease in apparent viscosity by approximately 10 cP and clear phase separation by d 90. The MPC-20 beverages with 0% SHMP exhibited stable particle size and apparent viscosities during storage. In the presence of 0.15% SHMP, particle size increased rapidly by 40 nm on d 90, implying the start of progressive gelation. On the other hand, highest apparent viscosities leading to gelation were observed in MPC-30 beverages at both concentrations of SHMP studied. These results suggested that beverages formulated with MPC-20 and 0% SHMP would have better storage stability by maintaining lower apparent viscosities. Further reduction of calcium using MPC-30 resulted in rapid gelation of beverages during storage.     

Studies on fish muscle protein. Nutritional consequences of the changes occurring during frozen storage

Samples of cod, whiting, herring, lemon sole and skate muscle were frozen and stored at ? 8°C for up to 20 months. Samples of cod muscle were also stored at ? 30°C. During storage at ?8°C the decrease in the solubility of the muscle proteins in 5% NaCl (denaturation) was most rapid in whiting followed in order by skate, cod, herring and lemon sole. Little change was detected in the NaCl solubility of cod muscle protein stored at ? 30°C. An increase in the pH was found to occur in all the species examined. The relationship between these changes and the toughening that occurs in fish muscle during frozen storage is considered. No nutritionally significant decrease in the lysine availability or the in vitro digestibility of the muscle proteins was found to occur in any of the species examined. In whiting, lemon sole and skate very small, statistically significant, increases in the available lysine content were detected after 7 months of storage at ?8°C and this may indicate that unfolding of the protein chains had occurred.     

Producing of natural clouding agents from orange and lemon peels

Two beverage clouding agents were produced from peels of Valencia orange and of Baladi Lemon. Three enzyme preparations, Pectinex ultra SP-L, Novo Ferm and Ultrazyme 100, were used under their estimated optimum conditions to hydrolyse pectin of the peel. Novo Ferm was proved the optimum preparation to use for preparing the two clouds. The chemical and physical properties of the produced clouds were evaluated. During storage the colour of lemon cloud was more stable than that of orange which showed significant browning. Sensory evaluation of two citrus drink when 5, 10 and 15% of the clouding agents were added, indicated that colour and appearance of drinks were improved. No bitterness was detected when orange cloud was added up to 15%. The cloudy of the produced drinks was stable after 42 days storage at 25 °C.     

Controlled Atmosphere and Ethylene Effects on Quality of California Canning Apricots and Clingstone Peaches

Storage at 2% O₂ plus 5% CO₂ at 1.1°C maintained higher flesh firmness and lower pH and retarded decay more effectively than air storage of immature (M1) and over-mature (M3) Patterson and Tilton apricot fruits. CA storage of fruits picked at the optimum maturity stage (M2) produced little benefit over air storage, however. -Treatment with 100 ppm ethylene for 48 hours accelerated softening and color change at 20°C compared to ripening in air and may potentially be used to prepare immature apricot fruits for canning in the shortest possible time. Large differences in storageability and canned quality following storage were found among the five clingstone peach cultivars tested. Loadel and Carolyn: peaches, if in sound condition at harvest, can be stored for up to 4 wk under 2% O₂+ 5% CO₂ at 1.1°C. Andross, Klamt and Halford peaches should be stored for shorter storage periods only. Fruits ripened at 20°C with ethylene (100 ppm for 48 hr) were similar to those ripened without it in appearance, texture, and flavor.     

Influence of protein content and storage temperature on the particle morphology and flowability characteristics of milk protein concentrate powders

Milk protein concentrate (MPC) powders are widely used as ingredients for food product formulations due to their nutritional profile and sensory attributes. Processing parameters, storage conditions, and composition influences the flow properties of MPC powders. This study investigated the bulk and shear flow properties of 70.3, 81.5, and 88.1% (wt/wt, protein content) MPC after storage for 12 wk at 25 and 40°C. Additionally, the morphological and functional changes of the MPC powders were investigated and correlated with flowability. After 12 wk of storage at 25°C, the basic flow energy values significantly increased from 510 to 930 mJ as the protein content increased from 70 to 90% (wt/wt). Flow rate index was significantly higher for samples with high protein content. Dynamic flow tests indicated that MPC powders with high protein content displayed higher permeability. Shear tests confirmed that the samples stored at 25°C were more flowable than samples stored at 40°C. Likewise, the higher-protein content samples showed poor shear flow behavior. The results indicated that MPC powders stored at 25°C had less cohesiveness and better flow characteristics than MPC powders stored at 40°C. Overall, the MPC powders had markedly different flow properties due to their difference in composition and morphology. This study delivers insights on the particle morphology and flow behavior of MPC powders.     

EFFECTS OF SHRINK FILM WRAP ON INTERNAL GAS CONCENTRATIONS, CHILLING INJURY, AND RIPENING OF HONEYDEW MELONS

Honeydew muskmelons (Cucumis melo L.) were individually wrapped with polyvinyl chloride (PVC) shrink film and stored at 2.5° or 7.5 °C for 21 days and examined, then held an additional 2 or 3 days at 20°C and examined again. Nonwrapped melons were the control. The concentration of CO₂ in the cavity of wrapped melons stored 21 days was 5.6% at 2.5°C, 9.1% at 7.5°C, but only 1.1% and 1.5% in the nonwrapped held at 2.5°C or 7.5°C, respectively. Wrapped fruit ripened slower than nonwrapped fruit during storage and subsequent holding at 20°C, after which time 70% of the wrapped melons were rated eating ripe, but 62% of the controls were overripe. Wrapped melons exhibited 30% less chilling injury (CI) symptoms than nonwrapped fruit stored at 2.5°C. The CI symptoms ranged from reddish-brown to dark-brown surface discolorations and sometimes included dry sunken areas of skin. Fresh weight loss was about 1 % in wrapped melons, but 5% in nonwrapped fruit, regardless of storage temperature. Decay incidence was about equal in wrapped and nonwrapped melons after storage at 2.5°C, but was greater for wrapped than nonwrapped melons after storage at 7.5°C. Soluble solids content was about 12.5% in wrapped and nonwrapped melons stored at either temperature.     

Improvement of Aroma and Shelf-Life of Non-alcoholic Beverages Through Cyclodextrins-Limonene Inclusion Complexes

Limonene is a monoterpene flavor compound found in several beverages. However, it easily degrades by oxidation reactions at acidic environment contributing to an undesirable off-flavor. Encapsulation technologies can protect compounds from degradation. This work focuses on the effect of using complexes of limonene with α-, β-, and γ- and HP-β-cyclodextrins in non-alcoholic beverages to improve flavor and shelf-life stability due to the chemical structure of cyclodextrins. Spray-drying technology was applied to prepare different cyclodextrin/limonene forms, from which the most promising was selected and further applied in simulated lemon juice beverages. Different drying process conditions were tested, namely feed temperature (120, 160, and 180 °C) and setting of prior incubation (temperature, room and 50 °C; time, 0.17 and 24 h). An inlet temperature of 160 °C favored the encapsulation of limonene into resulting nano/microparticles. Moreover, incubation for 24 h enhanced limonene retention for all complexes, especially for β-cyclodextrin/limonene complexes, which achieved 66% of encapsulation efficiency and a 6.25 w/w of limonene load. The β-cyclodextrin/limonene particles which enabled higher load (160 °C, 24 h) presented particle size ranging between 1 and 3 μm and were chosen to undergo an accelerated aging process in a lemon juice beverage model. This study revealed that the limonene content decreased over time for model and supplemented juice, but decreased less when β-cyclodextrin/limonene particles were added. After 10 days, which mimics 9 months of storage, 40% of complexed limonene remained in the model beverage.     

Optimization of lipid nanoparticle formation for beverage applications: Influence of oil type,cosolvents, and cosurfactants on nanoemulsion properties

The influence of flavor oil composition, cosolvents (glycerol and propylene glycol), and cosurfactant (lysolecithin) on the formation and stability of lemon oil nanoemulsions stabilized by sucrose monoesters was examined. At ambient temperature, nanoemulsions containing 1-, 3-, and 5-fold lemon oils were stable to droplet growth, whereas those containing 10-fold lemon oil were unstable. For 10-fold lemon oil nanoemulsions, the droplet growth rate increased with increasing temperature, cosolvent addition, and decreasing lysolecithin concentration, which was attributed to the influence of these factors on the phase inversion temperature. Clear nanoemulsions could be formulated that maintained small mean particle diameters (d ≈ 81 nm) during storage at ambient temperature for 1 month. The information generated in this study is useful for designing stable flavor nanoemulsions for applications in functional foods and beverages.     

The influence of storage temperature and storage time on color stability,retail properties and case-life of retail-ready beef

Steaks from three different muscles were either vacuum or carbon dioxide packed and stored for up to 24 weeks at three different storage temperatures (−1.5, 2, or 5 °C). Following storage, they were displayed for up to 30 h. CIE color coordinates, the oxidative states of myoglobin and pH were measured and muscle color, surface discoloration, retail appearance, and odor were evaluated prior to storage and during display (0, 1, 2, 4, 6, 24 and 30 h), and/or immediately prior to and following display. Prior to display, pH was negatively related to duration of storage, and samples stored at −1.5 °C had the highest and samples stored at 5 °C, had the lowest pH. Perception of muscle color was influenced by duration of storage and display, but lower storage temperatures appeared to produce a stabilizing effect. Both lightness of muscle color and deoxymyoglobin content were apparently not influenced by storage temperature or duration of storage or display. Both oxymyoglobin (OMB) and redness, as defined by CIE a* values, were lost progressively during storage and display, but this loss was progressively lower as storage temperature decreased. Yellowness of muscle color, as defined by CIE b* values, generally decreased as storage was prolonged, and this decrease was observed more quickly at higher storage temperatures. Surprisingly, b* values were not related to duration of display. Both surface discoloration and metmyoglobin (MMB) content increased progressively during storage and display. Samples stored at 5 °C displayed the most surface discoloration, while samples stored at −1.5 °C contained the least MMB and displayed the least surface discoloration. Retail appearance deteriorated progressively during storage in all samples stored at 2 and 5 °C and in samples stored at −1.5 °C, which were displayed for at least 24 h. Retail appearance also deteriorated progressively during display in samples stored at −1.5 and 2 °C for three weeks or longer and in samples stored at 5 °C for 0 to 15 and 24 weeks. In unstored samples, samples to be stored at −1.5 °C generally received the lowest retail appearance scores, but after prolonged storage and display, samples stored at −1.5 °C received higher retail appearance scores than samples stored at 5 °C, particularly when samples were stored for 12 weeks or longer and displayed for 1 h or more. Odor deteriorated progressively during storage when measured both prior to display and after 30 h of display. In samples stored for three weeks or longer, samples stored at −1.5 °C generally received the lowest odor scores and were perceived to have the least prevalent off-odors. Samples stored at −1.5 °C maintained a retail case-life of 30 h, when stored for up to 17 weeks, while samples stored at 2 and 5 °C maintained a retail case-life of 30 h, when stored for only eight and seven weeks, respectively. Consequently, storage life can be more than doubled by storage at subzero temperatures (−1.5 °C).     

不同茶饮料贮藏过程中品质的变化

本文从色泽、浊度及活性成分含量三个方面分析不同茶饮料的品质变化特征，分别对高酸绿茶饮料、低酸绿茶饮料、高酸红茶饮料及低酸红茶饮料在不同贮藏条件下的可溶性固形物含量、透光率、浊度、色差、茶多酚含量、表没食子儿茶素没食子酸酯（Epigallocatechin gallate，EGCG）含量等指标进行测定，探究不同茶饮料在不同贮藏条件（温度、时间）下品质变化的情况。结果表明:不同茶饮料在贮藏过程中，透光率无显著变化；高酸绿茶饮料在4 ℃及25 ℃条件下贮藏，随贮藏时间的延长，浊度显著增加，贮藏至第180 d，分别增加了52.04%、34.12%，红茶饮料浊度无显著变化；不同茶饮料在贮藏过程中，随贮藏时间的延长，L*值降低，a*值及b*值增加，25 ℃条件下贮藏至180 d，高酸绿茶饮料、低酸绿茶饮料、高酸红茶饮料及低酸红茶饮料的L*值分别降低了31.86%、39.98%、30.22%及37.73%；茶饮料中的茶多酚及EGCG含量随着贮藏时间的延长而降低，EGCG降解程度较茶多酚高，在55 ℃条件下贮藏15 d，高酸绿茶饮料、低酸绿茶饮料、高酸红茶饮料及低酸红茶饮料的茶多酚含量分别降低9.08%、10.28%、13.39%及18.63%，EGCG含量分别下降了35.32%、42.18%、47.22%及49.03%。     

Effects of N6-Benzyladenine and Storage Temperature on Shelf-Life and Quality of Raw and Cooked Broccoli (Brassica oleracea L. var. italica)

Fresh broccoli heads were dipped in solutions containing 20 ppm N⁶-benzyladenine (BA) with 0.1% Tween-20 or water with 0.1% Tween-20 for 30 sec then stored for 5 wk at 2° and 5°C. Broccoli heads receiving BA treatments maintained higher subjective quality ratings for color, turgidity, aroma, flavor, and texture throughout the 5-wk period. Gardner color measurements and total chlorophyll were significantly higher for samples treated with BA and stored at 2°C than for controls. Samples stored at 2°C had lower shear resistance than those kept at 5°C. The content of hot water insoluble materials (fiber) was much less in broccoli heads treated with BA than in untreated heads. Maintenance of good quality by BA treatment and 2°C storage was reflected in all parameters of sensory evaluations for cooked broccoli. Loss of color and reduction of quality were observed in raw and cooked broccoli during 4 wk of storage. Evaluations of quality parameters and color measurements were greatly influenced by the turgidity factor.     

Kinetics of haze formation and factors influencing the development of haze in clarified apple juice

The rate of haze formation in commercial clarified apple juice stored at 4, 25 and 37°C was monitored over a 16 to 35-week storage period. Changes in turbidity, tannin content and browning index were evaluated. The juice appeared virtually clear and had very little colloidal particles during the initial stages of storage. After 24 weeks, an increase in turbidity of 2.32 NTU was observed for juice samples stored at 37°C. An increase of 0.58 and 0.95 NTU was observed for samples stored at 25 and 4°C, respectively. There was a general decrease in tannin content and an increase in browning index with storage; this effect was most pronounced for samples stored at 37°C. The rate of haze formation and tannin depletion in juice samples followed first-order reaction kinetics. Light and headspace did not affect haze formation. NaCl and CaCl₂ increased haze development while sucrose (up to 60%), urea (0.5 M), and EDTA (up to 0.01 M) had little effect. Addition of sodium dodecyl sulfate retarded haze formation.     

USE OF FLEXIBLE POLYMER MATERIAL FOR PACKAGING FRESH PEACHES

Fresh peaches (Prunus persica) were overwrapped in trays with 1 of 3 formulations of flexible polyvinyl chloride (PVC) film that differed in gas transmission rate or they were held in nonwrapped trays (controls). The CO₂ transmission rate at 0°C for PVC type III film was 280 mL/m^2. h (1 atmos); that of type II was 4 times greater and that of type I, about 5 times greater. The peaches were stored either 14 days at 0° or 7.5°C, or 7 days each at 0° and 7.5°C plus 2 days at 20°C to simulate retail display. The mean CO₂ levels were 10, 7.2 and 4.7% in packages that were wrapped with PVC III film and held at 7.5°, 0°/7.5° and 0°C, respectively. CO₂ in packages wrapped with PVC I or II was below 3% at each storage temperature. O₂ concentration remained about 4% in all packages. Weight loss was less and fruit was firmer among those packaged in PVC III than among nonwrapped controls at each of the 3 storage temperatures. Storage temperature had no effect on weight loss or of fruit held in PVC III film. External appearance of fruit packaged with the 3 types of film was significantly better than that of the controls. Internal appearance of the peaches was unaffected by any of the treatments. A microatmosphere favorable for fresh peaches can be maintained within packages overwrapped with polymer films that are selectively permeable to respiratory gases.     

UHT-Sterilized Peanut Beverages: Changes in Physicochemical Properties during Storage

Strawberry-flavored and chocolate-flavored peanut beverages were produced in a pilot plant, UHT sterilized at 137°C for 4 sec and 20 sec, aseptically filled and stored at 5, 20 or 35°C. Microbiological and physicochemical properties of the beverages were periodically assessed for up to 6 mos. No Microbial growth was observed. The pH decreased while homogenization and sedimentation indices increased with time in all beverages at all temperatures. Color lightness decreased during the first 6 wk and remained constant afterwards. Viscosity of strawberry-flavored beverage was constant whereas chocolate-flavored beverages gelled after 19 wk at all temperatures. Proteolysis was <6% in gelled beverages.     

A COMPARISON OF ARTIFICIAL SWEETENERS' STABILITY IN A LIME-LEMON FLAVORED CARBONATED BEVERAGE

Three intense sweeteners, aspartame, acesulfame‐K and sucralose, were incorporated singly in lime‐lemon flavored carbonated beverage in optimized concentrations on a sucrose equivalence basis at controlled pH conditions. The beverages were stored for 60 days at 4, 27 and 37C and the sweetener concentration determined by HPLC. The loss of aspartame was maximum (29.5%) while that of sucralose was minimum (1.9%) at the end of 60 days' storage at 37C. In the case of acesulfame‐K, the loss was 6.1%. Sucralose was more stable than the other sweeteners.     

Evaluation of Enterococcus faecium NRRL B-2354 as a surrogate for Salmonella enterica in milk powders at different storage times and temperatures

While the increase in thermal resistance of microorganisms at reduced water activity is demonstrated for low-moisture food products, the effect of storage time on the thermal resistance of microorganisms in low-moisture foods is not well established. As low-moisture foods are stored for long periods and are used as ingredients, cross-contamination can occur at any time period before the lethality step. Therefore, this study was designed to investigate the effect of storage time (30, 60, and 90 d) on the thermal resistance of Salmonella and Enterococcus faecium NRRL B-2354 in milk powders at a low water activity of 0.10 (conservative level). In this study, 2 milk powders, whole milk powder (WMP) and nonfat dry milk (NFDM), were inoculated with a 5-serotype Salmonella cocktail or E. faecium and equilibrated to a water activity of 0.10. The thermal resistance of Salmonella and E. faecium in WMP and NFDM were determined at different storage times (30, 60, and 90 d) at 85°C. The storage time had no effect on the thermal inactivation kinetics of Salmonella within 90 d of storage at 85°C. In the second part of this study, isothermal treatments were also conducted at higher temperatures (90 and 95°C) to evaluate the suitability of E. faecium as a surrogate for Salmonella in milk powders. The D-values of Salmonella in WMP with 30 d of storage at 85, 90, and 95°C were 7.98, 3.35, and 1.68 min. The corresponding values for E. faecium were 16.96, 7.90, and 4.16 min. Higher D-values of E. faecium indicates that it is a conservative surrogate. Similar results were found for NFDM. In general, D-values of both microorganisms are slightly higher in NFDM than WMP. Two primary models (log-linear and Weibull) were compared for their goodness-of-fit. The Weibull model was found to be more appropriate than the log-linear model. This study provides valuable information for establishing process validation for the pasteurization of milk powders.