UHT-Sterilized Peanut Beverages: Kinetics of Physicochemical Changes during Storage and Shelf-Life Prediction Modeling

Strawberry-flavored (S04) and chocolate-flavored (C04 and C20) peanut beverages UHT-sterilized (137 °C, 4 sec or 20 sec) and aseptically filled in Tetra Briks were stored for 6 mo at 5, 20 and 35 °C. Sensory characteristics and kinetics of physicochemical changes were studied. The changes were of zero (pH of S04, and sedimentation and homogenization indices of all beverages) and first (pH of C04 and C20, viscosity and color lightness of all beverages) order. Reaction rate constant and Gibb's free energy increased with temperature. Activation energy followed Arrhenius equation. Deterioration in beverage sensory qualities highly correlated with increase in sedimentation index and decrease in pH and emulsion stability. Shelf-life prediction models were constructed based on sensory and kinetics data. The shelf-life was estimated to be 4–7 mo for beverages stored at 30–35 °C.     

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.     

Effect of Storage Temperature, Time, and Method of Slicing on Microbial Population and White Film Development in Vacuum Packaged, Dry-Cured Ham Slices

Aged ham slices, bone-in or boneless, were vacuum-packaged and stored at 2°C or 24°C for 8 wks. White film was more abundant on bone-in slices. Color was not affected by treatment. Aroma remained normal at 2°C for all slices but abnormal aromas developed in some 24°C packages by 2 wk and in all packages by 8 wk. Aerobic and staphylococci counts on bone-in and boneless slices at 24°C were high at 2 wk and remained high, while lactobacilli counts were highest at 2 wk, decreased to initial levels by 4 wk and increased again to 8 wk. Yeast and mold counts at both temperatures decreased with storage but at a faster rate in bone-in hams.     

Effects of Processing and Storage on the Water-Soluble Vitamin Content of Human Milk

Effects of four heat treatments (62.5°C, 30 min; 72°C, 15 sec; 88°C, 5 sec; and 100°C, 5 min) and frozen storage (?20°C, 4 wk) on water-soluble vitamin content of composite samples of mature human milk were determined. No changes in riboflavin, biotin, and total pantothenic acid content were observed after any of the treatments. Heating at 100°C for 5 min decreased thiamin, vitamin B₁₂, and vitamin C contents. Vitamin Bs content was reduced by heating at 88°C and 100°C. Free folate was not affected by heating while total folate concentration was decreased similarly by all heat treatments. During frozen storage at ?20°C, niacin and free pantothenic acid concentrations were reduced; riboflavin, vitamin Bs, biotin, total pantothenic acid, vitamin C, and vitamin B₁₂ were unaffected; while measurable thiamin and free folate concentrations increased. Overall, the two lower temperature treatments were less detrimental to the water-soluble vitamins in human milk.     

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 Thiamin Degradation in Solutions under Ambient Storage Conditions

Thiamin is being incorporated into a variety of nutritionally enhanced beverages. Although thiamin degradation during thermal processing has been extensively studied, minimal data exist regarding its stability in solution during ambient storage. This study collected kinetic data for thiamin degradation in solutions as a function of pH, buffer type, and buffer concentration at 25 °C. Thiamin was incorporated into sodium phosphate and citrate buffer solutions, each prepared at 0.02 and 0.1 M and pH 4, 5, 6, and 7. Experimental solutions were stored in an incubator at 25 °C. Thiamin concentrations were analyzed at 9 time points over a 42‐wk period. Thiamin degradation data were modeled using pseudo‐1st‐order kinetics. Thiamin stability generally decreased as pH and buffer concentration increased in both phosphate and citrate buffers. In 0.1 M phosphate buffer, the time for a 10% loss of thiamin decreased from 79 wk at pH 4 to 3 wk at pH 7. At pH 6 and 7, thiamin stability was greater in citrate buffer than in phosphate buffer. However, at pH 4 and 5, thiamin stability was greater in phosphate buffer than citrate buffer. To optimize thiamin stability in low pH beverages, phosphate buffer would be more appropriate to use than citrate buffer, whereas citrate buffer should be used for better thiamin stability in high pH beverages.     

Comparison of changes occurring in rheological properties of gelled tissue and model sausage prepared from duck breast muscles stored at −2°C and −18°C

The changes of rheological parameters of gelled tissue and model sausage prepared from duck breast muscles stored at ?2°C and ?18°C were compared. The changes of conventional elasticity and flowability and the sum of reciprocal immediate elasticity modulus and reciprocal elasticity modulus of gelled tissue, and conventional plasticity and Newtonian viscosity of model sausage are comparable for both temperatures and are higher at ?2°C than ?18°C. At both temperatures the changes occurring in rheological parameters of model sausage can not be predicted according to the changes in rheological parameters of gelled muscle tissue.     

Modeling of Salt Diffusion in White Cheese during Long-Term Brining

Salt transport in white cheese was investigated at two brine concentrations (15 and 20% w/w) and at three temperatures (4, 12.5 and 20°C) for each brine concentration. Two mathematical models were developed based on treating the cheese samples as finite or semi-infinite bodies. Theoretical and experimental salt concentration profiles were in good agreement. The semi-infinite model was valid only for low Fourier numbers, i.e., Fo≤0.07. Effect of convectional flow was insignificant. Salf diffusivity remained constant with time, and an Arrhenius-type equation described its variation with temperature. Salt diffusivity in white cheese was estimated as 0.21 × 10^?9 m²/sec at 4°C and 0.31 × 10^?9 m²/sec at 12.5°C for both brine concentrations and as 0.39 × 10^?9 m²/sec for brine concentration 15% (w/w) and 0.34 × 10^?9 m²/sec at 20°C for 20% (w/w).     

Shelf Life and Quality of Freshly Squeezed, Unpasteurized, Polyethylene-Bottled Citrus Juice

Florida's chief orange and grapefruit cultivars were used to produce five freshly squeezed, unpasteurized, polyethylene-bottled juices using commercial conditions. Juices were stored at different temperatures. Shelf life depended primarily on storage temperature: ?1.7°C, 20–23 days; 1.1°C, 16–22 days; 4.4°C, 10–16 days; and 7.8°C, 5–8 days. Staleness was the primary off-flavor limiting shelf life at the three lower temperatures while spoilage with diacetyl was primarily responsible at 7.8°C. At the three lower temperatures, microbial counts generally decreased markedly during storage, while at 7.8°C, an increase was generally noted. Ascorbic acid retention after 2 wk of storage at the three lowest storage temperatures was about 91–93% for two orange juices and 86–88% for the grapefruit juice.     

Effect of Phosphate Blends on Stability of Cod Fillets in Frozen Storage

Atlantic cod fillets were dipped in commercial tripoly or metaphosphate solutions, frozen and stored at either –12 ° 0.5°C or –30°C (constant or with daily programmed fluctuations to ?26°C) for up to 26 wk. Phosphate treatments at both storage temperatures decreased thaw drip and cooked drip and yielded a product with higher raw and cooked moisture. Protein content of cooked drip from fillets stored at –12°C was reduced by phosphate treatment; no significant difference was found between treated and control samples at –30°C. Although salt extractable protein was lowered, phosphate treatment did not affect dimethylamine/formaldehyde formation. Sensory evaluation of treated fillets stored at –30°C (with daily fluctuation to –26°C) revealed phosphated fillets to be the most tender and, after 26 wk storage, the most highly acceptable. Tripolyphosphate treatment significantly retarded the increase of expressible fluid under abusive conditions of frozen storage.     

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.     

Pectolytic Enzyme Activity During Intermittent Warming Storage of Peaches

Pectin enzyme evolution in peaches intermittently warmed at 15°C (15°C-IW) and at 20°C (20°C-IW) for 24 hr every 8 days of storage at 0°C, was followed. Cold storage increased PME activity until a constant level was reached, whereas PG decreased after 2 wk. 15°C-IW had a similar effect to conventional cold storage. 20°C-IW induced a different behavior, PG activity increasing and PME activity decreasing after 2 wk of storage. This different behavior seemed to be related to the development of chilling injury, since 15°C-IW did not alleviate chilling injury but 20°C-IW did. Chilling injury development during storage was associated with continuous PME activity and inhibition of endo-PG activity after the second week of storage, regardless of exo-PG activity.     

Effect of Irradiation on Discoloration, Phenols and Lipids of Potatoes

The effect of two irradiation doses, 10 and 100 krad, on discoloration, phenolic content and lipid content of Katahdin and Russet Burbank potatoes was studied. Potatoes were stored 1, 4 and 26 wk at 5°C and 20°C following irradiation. Irradiation increased discoloration and phenols and decreased crude lipids and the phospholipids. Potatoes receiving 100 krad dose discolored more, were higher in phenols, and lower in lipids than those given 10 krad dose. Potatoes stored at 5°C discolored more and were higher in phenols and in lipids than those stored at 20°C. Increased storage at both temperatures resulted in greater discoloration, increased phenolic content and decreased lipids content.     

The influence of storage on aroma, soluble solids, acid and colour of sour cherries (Prunus cerasus L.) cv. Stevnsbær

The present study involved a laboratory scale experiment where the impact of post-harvest storage on the quality of sour cherries (Prunus cerasus L.) cv Stevnsbær was investigated. Cherries were stored for 7 days at temperatures of 2??°C, 10??°C, 20??°C, and 30??°C, and at 20??°C in combination with a 20% CO₂ atmosphere. Cherry quality was assessed by analysis of soluble solids, titrateable acids, anthocyanins and aroma compounds. The content of soluble solids of cherries decreased at storage temperatures above 10??°C. The anthocyanin content of cherries decreased during storage at all temperatures. A decrease, followed by an increase, in titrateable acid was observed for all temperatures except 2??°C. Aroma components were also affected by storage time and temperature. The level of benzaldehyde decreased during storage at higher temperatures, while those of eugenol and vanillin increased at all temperatures. The levels of "off" odour compounds, like acetic acid and fermentation alcohols, increased at higher temperatures during storage. The CO₂-enriched atmosphere (20%?CO₂) did not affect the different quality factors significantly.     

Thermal degradation kinetics of anthocyanins from Chinese red radish (Raphanus sativus L.) in various juice beverages

Thermal and storage stabilities of red radish anthocyanins (RRAs) in various juice beverages (apple, grape, peach, pear, pomegranate and lemon) were studied over temperature range 70–90 °C and 4–25 °C. RRAs degradation in all juice beverages followed first-order reaction kinetics. RRAs showed a much faster degradation rate during storage at room temperature (t _1/2 value ≤84.0 days) than did in refrigerated temperature (t _1/2 ≥value 130.9 days). The rate constant (k), E _a and Q ₁₀ values for RRAs in juice beverages varied from 1.33 to 0.33, 47.94 to 14.77 kJ mol^?1 and 1.16 to 1.89 at 70–90 °C. During heating, RRAs in peach and pomegranate showed higher stability than others at these temperatures. There was a positive correlation (R ² > 0.9128) between ascorbic acid content of juice beverages (8–36 mg/100 mg) and stability of RRAs at 70–90 °C. It was found that RRAs in apple and pear juice beverage were more stable than in other juice beverages.     

Changes in the Tenderness of Meat Cooked at 50–65°C

Warner-Bratzler (WB) shear force values obtained for stretched veal muscles decreased as cooking temperatures were increased from 50 to 60°C. Increased proteolytic enzyme activity at these temperatures to give accelerated aging did not appear to explain the effects since there was still a substantial decrease in shear force with increase in cooking temperature from 50 to 60°C, even when well aged (7 wk at 5–6°C) meat and meat cooked for 24 hr was used. A more likely explanation was that, even at these relatively low temperatures, changes in connective tissue were involved since (a) the magnitude and direction of the change in shear force with increasing temperature was dependent on animal age and cooking time; (b) the effect of recooking at 80°C was dependent on animal age; and (c) the effects of increasing the cooking temperature and/or time on adhesion between the meat fibres was significantly greater for the samples from the younger animals.     

Effect of Heat Treatments on In Vitro Digestibility of Delactosed Whey Protein as Determined by the Digestion Cell Technique

Diafiltered whey protein concentrates (WPC) were heated, in liquid form, under various conditions of time and temperature. Protein and amino acid digestibilities were determined by in vitro pepsin and pan-creatin digestion with continuous dialysis. Whey nitrogen digestibility decreased (P < 0.05) after heating at 121°C for 5000 sec. Heating WPC for 5000 set at temperatures below 121°C increased the digestibility of all amino acids except alanine and lysine at 75°C, and methionine and lysine at 100°C. In general, the longer was the heating period at 100°C or 121°C the lower was the amino acid digestibility. These results emphasized the importance of structural modifications brought about by heat treatments on protein digestibility.     

Hydroxymethylfurfural Accumulation in Applesauce Packaged in Multilayer Polymer Films and Glass

Applesauce packaged in four different multilayer polymer films and glass was evaluated for changes in hydroxymethylfurfural content during storage. Packages were held for 15 wk at 20°, 30°, 37° and 43°C. Hydroxymethyfurfural content was measured by HPLC analysis every 5 weeks. For all package types more HMF was measured at higher storage temperatures as expected, however, total amounts of HMF also varied according to package type. Comparison of HMF across . package types as an index of thermal history would be of questionable value.     

Accelerated Kinetic Study of Aspartame Degradation in the Neutral pH Range

The degradation of aspartame in solution as a function of temperature (70–100°C), buffer concentration (0.01–0.1M phosphate), and pH (6–7) was studied in order to estimate losses during thermal processing and storage of aseptic milk-based drinks. Prior data have been mostly on acid carbonated beverages. First order rate constants were obtained in all the conditions with activation energies in the range 14–20 kcal/ mole. An increase in both pH and buffer concentration caused an increase in rate of loss. These data were used to predict losses that would occur during pasteurization and sterilization conditions. Experiments at 4 and 30°C showed significant losses would occur during 4 and 30°C temperature storage and extrapolation from high temperatures predicted faster degradation rates than those found.     

Changes in Texture of Green Peas during Freezing and Frozen Storage

The effects of freezing (still-air, air-blast, and Freon immersion freezing) and frozen storage (?5°, ?10° and ?15°C for 0 to 48 wk) on texture of cooked frozen peas were examined. Peas frozen by a Freon-12 immersion method with no appreciable damage to cell structure had firmer and more chewy sensory textural quality compared to those peas frozen by a slower freezing method. Sensory tenderness decreased initially and then increased with storage time to the maximum storage times of 6 wk in ?5°C storage, 16 wk in ?10°C storage, and 48 wk in ?15°C storage. Sensory chewiness increased initially, then remained constant with storage time except in ?15°C storage. Generally, the lower storage temperature resulted in less sensory chewiness. The correlation coefficients (r) between sensory and objective measurements for tenderness and chewiness were 0.76 and 0.88 (P < 0.05), respectively.