Effect of Storage on 5-Hydroxymethylfurfural (HMF) Formation and Color Change in Jams

In this study, the effects of storage temperature (10, 20, and 37°C) and time (0, 2, 4, and 6 months) on the HMF and color values in strawberry, cherry and apricot jams were studied. Results showed that the HMF and total color difference (ΔE) values of all jams were increased linearly with storage time and higher values were found at higher storage temperature. Kinetic model was applied to changes in HMF and ΔE. Changes in HMF and ΔE were explained using zero-order reaction kinetics and the dependence of the rate constant on temperature was described by the Arrhenius equation     

Kinetics of ascorbic acid degradation in fruit-based infant foods during storage

The kinetics of ascorbic acid (AA) degradation in a fruit-based beikost product added with AA were determined after storage at 4, 25, 37 and 50 °C during 4, 8, 12, 16 and 32 weeks in plastic polypropylene/ethylene–vinyl alcohol vacuum packaging. It was confirmed that AA degradation followed an Arrhenius first-order kinetics, with an activation energy of 20.11 ± 0.33 kcal mol⁻¹. No AA losses at 4 °C were recorded during the entire storage period. In contrast, a time- and temperature-dependent decrease (p < 0.05) in AA was observed at the other tested temperatures – the degradation rate decreasing from 50 °C to 25 °C, as expected. AA percentage retention at the end of storage ranged between 6.4% (50 °C/16 weeks) and 100.9% (4 °C/32 weeks).     

Acrylamide in almond products

Acrylamide was determined in 86 different almond products, such as roasted almonds, almond-containing bakery products, raw almonds, and marzipan. The highest acrylamide concentrations were found in dark roasted almonds, while only moderate acrylamide contents were determined in bakery products. Roasting experiments under different process conditions showed that acrylamide increases with time and that temperature has a much stronger effect on acrylamide formation than time. During roasting reducing sugars are consumed faster and to a larger extent than free asparagine, suggesting that the content of reducing sugars may be a critical factor for acrylamide formation in roasted almonds. Acrylamide was found to decrease in roasted almonds during storage at room temperature.     

Effect of high pressure processing on the stability of anthocyanin,ascorbic acid and color of Chinese bayberry juice during storage

The stability of anthocyanin (Cy3Gl) and ascorbic acid (AA) of pressure treated Chinese bayberry (Myrica rubra Sieb. et Zucc.) juice was investigated during storage at temperature of 4 °C and 25 °C. Samples of Chinese bayberry juice (350 mL each, packed with a polyethylene bag) were processed at 400, 500, 600 MPa in room temperature for 10 min. The retention ratio of Cy3Gl and AA content after pressure treatment was more than 98% and 96%, respectively. Both Cy3Gl and AA of pressure treated juice were more stable during storage as compared to those of the untreated control juice. The degradation of Cy3Gl and AA of samples during storage could be described using first order kinetic model. It was observed that there was a significant (p < 0.01) correlation between changes of Cy3Gl and AA content for all tested samples of Chinese bayberry juice during storage.     

Fluorescence and color as markers for the Maillard reaction in milk–cereal based infant foods during storage

Free and total fluorescence compounds and color formation were measured in three different milk–cereal based infant foods stored at 25, 30 and 37 °C for 9 months to evaluate the advanced and final stages of the Maillard reaction. Milk–cereal infant foods containing honey (B) or fruits (C) had fluorescent values higher than sample (A) without them. This difference could be ascribed to the higher monosaccharide (fructose and/or glucose) content of (B) and (C), which could increase susceptibility to the Maillard reaction. However, for color increase (ΔE), no significant differences (p < 0.05) among the three types of samples were found. During the storage period, a gradual increase in fluorescence and color was observed, and statistically significant differences among the three temperatures studied were detected, the values being greater at 37 °C than at 30 °C and 25 °C.     

Infrared pasteurization of raw almonds

Due to outbreaks of salmonellosis associated with whole raw almonds, an infrared (IR) pasteurization process was investigated for its efficacy in improving the safety of raw almonds. After almonds were heated to 100, 110 and 120 °C with IR, they were cooled at ambient temperature to a holding temperature of 70, 80 or 90 °C before being transferred to a custom-designed holding device for different time periods up to 60 min. We observed that holding almonds at 90 °C for 10-15 min reduced the Pediococcus population size by more than 5-log and holding at 80 °C for longer than 22 min provided more than 4-log reduction, thus satisfying the targeted 4-log reduction required in the almond industry. The L^∗a^∗b^∗ color values of whole almonds were not affected significantly (P > 0.05) by the IR process whereas the a^∗ and b^∗ color values of ground almonds changed significantly (P < 0.05). The sensory panel did not detect any significant difference (P > 0.01) in appearance, texture, flavor and overall quality of pasteurized almonds compared with untreated samples.     

Effect of storage on resistant starch and amylose content of cereal–pulse based ready-to-eat commercial products

A wide range of ready-to-eat (RTE) foods, with varied shelf life are commercially available to meet the increasing demand for convenience foods, both by the Armed Forces and the public at large. The study evaluated the effect of storage on the resistant starch (RS) and amylose content of selected ready-to-eat (RTE) cereal–pulse based processed foods viz., pongal, khara bhath, dal fry, bisibele bhath, rajmah and kesari bhath, developed by Defence Food Research Laboratory, Mysore. RS was quantified directly in the residues obtained after removing digested starch in simulated physiological conditions. Nutrient composition and carbohydrate profile of the foods were also analyzed. The carbohydrate profile indicated low amounts of sugars, except in case of kesari bhath. The total starch content ranged from 14.5 to 24 g% while amylose ranged from 1.2 to 7.2 g%, respectively. The total and resistant starch in the RTE foods varied depending on the ingredients used and type of processing. Foods containing higher amylose content were found to have maximum increases in RS content after storage. Storage at ambient conditions resulted in significant increases (p < 0.05) in RS and TS content of RTE foods. The findings reveal that the RTE foods studied hitherto contained appreciable quantities of RS, which further increased on storage.     

Effects of Roasting on the Characteristics of Australian Wattle (Acacia victoriae Bentham) Seed and Extracts

The effects of roasting at 200°C for up to 30 min on the color, chemical composition, and trypsin inhibitor activity of wattle seed (Acacia victoriae Bentham) and its extracts were studied. Results showed that roasting induced significant (p < 0.05) changes in color difference index (ΔE*_ab) of flours compared to seeds. Furthermore, chemical analysis showed that protein solubility decreased as a result of roasting. Polyacrylamide gel electrophoresis and reverse phase high performance liquid chromatography of soluble proteins showed that large molecular weight polypeptides were rapidly broken down, with resultant formation of smaller, more hydrophilic fragments. Both total and soluble carbohydrates decreased during roasting, most likely due to Maillard-type reactions and caramelization, and polyacrylamide gel electrophoresis and spectrophotometric assays confirmed the essential elimination of trypsin inhibitor activity after 20 min of roasting.     

Advances in the study of the kinetics of color and fluorescence development in concentrated milk systems

The kinetics of color and fluorescence development in systems containing whole milk powder (WMP), sucrose (S) and water were studied; the influence of three design variables: pH (6, 7 and 8), temperature (105, 122.5 and 140 °C) and WMP/S ratio (R = 0.3, 0.68 and 1.06) being particularly investigated. The Kubelka-Munk index (K/S), luminance or lightness (L), optical density (OD) and fluorescence (F), were measured at different reaction times. Reaction pseudo-order (n) varied between 0 and 1 and reaction rate constants for the development of fluorescence and the color parameters were found to be more dependent on temperature than on R at all measured pH values. Temperature dependence of CP was analyzed through the activation energy (E_a) values. The variables F and OD, which are related to the molecular aspects of the systems, showed the extreme values of E_a, while than K/S and 100/L, related to the macroscopic appearance or reflectance, showed intermediate E_a values and lower dependence with R and pH. When compared to the variables related to brown pigment development, fluorescence development showed a higher relative change, which shows its higher sensitivity as a reaction marker. The variables that most affected color and F development were temperature and protein concentration, respectively.     

A novel approach for color degradation kinetics of paprika as a function of water activity

The influence of temperature and water activity on color degradation in paprika powders was investigated. The Hunter color parameters (L, a, b), hue angle (h), and total color difference (TCD) were used to estimate the color changes of paprika during thermal treatment at different temperatures (60, 80 and 99 °C) and water activities (0.459, 0.582 and 0.703). The changes in L, a, b and TCD values were significantly influenced by the processing time, temperature and water activity. The color changes during processing and storage were described by a first order kinetic model. The temperature dependence of the degradation followed the Arrhenius relation. Samples with a high water activity exhibited a high rate constant of the color degradation. The effect of water activity on activation energy was not significant. A linear relationship between the water activity and rate constant of the color parameters was found. By incorporating the linear relationship k_refa_w into the Arrhenius equation, a modified Arrhenius equation was proposed which was used to predict paprika color changes as influenced by temperature and water activity.     

Effects of postmortem storage time on color and mitochondria in beef

To assess the effects of aging time (0, 15, 30, and 45 d) and temperature (0 or 5 °C) on beef mitochondria and steak color, vacuum packaged longissimus (n = 15) and cardiac muscles were assigned to 1 of 6 temperature × time combinations. As time increased, initial red color intensity increased whereas both mitochondrial oxygen consumption and color stability decreased. The decrease in mitochondrial oxygen consumption associated with longer aging times will increase initial color intensity. However, this improvement in color development will be negated by the decreased color stability that results from the effects of storage on mitochondria.     

杏仁乳生产防浮防沉技术研究

确定了杏仁乳生产工艺。杏仁乳稀释倍数为１５,添加０．１％柠檬酸调整乳液ｐＨ值为４．２３左右,并加入１０％白砂糖,０．３％ＰＧＡ和０．２％单甘酯。生产的杏仁乳可溶性固形物＞１０％,蛋白质含量＞１％,经１个月观察无上下沉现象。     

鱼丸贮藏过程中品质变化动力学模型研究

研究不同温度下贮藏过程中鱼丸细菌总数、脂肪氧化值(TBA值)及挥发性盐基氮(TVB-N值)随存放时间的变化规律及其动力学特性,建立了细菌总数、TBA值、TVB-N值与贮藏温度和贮藏时间的动力学模型,以预测和控制鱼丸在贮藏过程中的品质和货架期。贮藏过程中鱼丸的细菌总数增加,脂肪氧化和腐败现象加重,随贮藏温度的上升,鱼丸品质劣化速度加快。细菌总数、TBA值和TVB-N值对一级化学反应模型和Arrhenius方程具有很高的拟和精度。     

Kinetics of changes in the physical quality parameters of fresh tomato fruits (Solanum lycopersicum, cv. ‘Zinac’) during storage

The effects of storage at different temperatures (2, 5, 10, 15 and 20 °C) conditions on whole tomato (Solanum lycopersicum, cv. ‘Zinac’, fruits harvested at mature-green stage) quality parameters, such as colour, chilling injury, firmness, weight loss and total phenolic content, were investigated during a month period.     

Effect of storage conditions on furosine formation in milk–cereal based baby foods

The effect of storage during 9 months at 25, 30 and 37 °C on furosine formation in three milk–cereal based baby foods was studied to evaluate development of the Maillard reaction. Furosine was measured by HPLC-UV. Immediately after the manufacturing process, furosine contents were 310–340 mg/100 g protein and at the 9th storage month were 426–603 mg/100 g protein. Storage time and temperature have a significant increase (p < 0.05) of furosine content during storage. Furosine contents were higher in sample containing honey than in those without honey. Interactions (p < 0.05) between storage time and temperature or type of sample were found. A predictive model equation of the evolution of furosine during storage explaining 80% of the variability in furosine content was obtained. The blockage of lysine through storage calculated using the furosine and total lysine provided values ranged from 9.5% to 18.1% for analysed baby foods.     

Storage length,storage temperature,and lean formulation influence the shelf-life and stability of traditionally packaged ground beef

The effect of storage length and temperature on the shelf life of three ground beef formulations (lean:fat: 73:27, 81:19 and 91:9) was investigated. Coarsely ground beef was stored at − 1.7 or 2.3 °C for up to 28 d. Traditional overwrap packages were produced every 7 d prior to retail display for 24 h. Lipid oxidation (TBARS), subjective color, instrumental color, and aerobic bacteria were evaluated after 0 and 24 h of display. Formulation influenced initial L* and subjective color values (P < 0.05). Storage temperature did not affect initial color, but product stored at 2.3 °C was more discolored after 24 h (P < 0.05). Aerobic bacteria increased as storage d and temperature increased (P < 0.05). Initial TBARS increased through d 21, but were lower after 28 d. Overall, initial characteristics depended on formulation; however, ground beef shelf-life and stability were largely influenced by storage length and storage temperature.