Changes In Peroxide Value Research Articles

Analisis Umur Simpan Bubuk Kakao dalam Kemasan Plastik Standing Pounch Menggunakan Pendekatan Model Arrhenius

Cocoa powder is usually used to be a raw material in the chocolate products. In the large scale production, cocoa powder must be stored at specific time period before it was used. The quality of cocoa powder can decrease during storage period hence shelf life analysis of cocoa powder is needed. The aim of this study was to determine the shelf life of cocoa powder by Accelerated Shelf Life Testing (ASLT) Method with Arrhenius Model Approach. Cocoa powder was stored at different temperature (30, 40, and 50oC) and different packaging type (plastic with zipper and paper craft with zipper) to simul atedacceleration of damage as a result of temperature increase. Cocoa powder contained high level of fat so it more easily gone rancid. Moisture content and peroxide value were observed periodically that shown the quality parameters of cocoa powder. Initial moisture content and fat content of cocoa powder were analyzed by gravimetric method. Degree of rancidity which was shown with peroxide value was analyzed by iodometric titration method. According to the change of peroxide value, the shelf life of cocoa powder can be estimated.

Effect of mechanical extraction parameters on the yield and quality of tobacco (Nicotiana tabacum L.) seed oil.

The aim of this study was to investigate how the combination of extraction parameters, such as extraction temperature seeds preheating and screw rotation speed, influenced the yield and chemical quality of tobacco seed oil (TSO). For its peculiar properties, TSO can be used for several purposes, as raw material in the manufacturing of soap, paints, resins, lubricants, biofuels and also as edible oil. TSO was obtained using a mechanical screw press and the quality of the oil was evaluated by monitoring the free fatty acids (FFA), the peroxide value (PV), the spectroscopic indices K232, K270 and ΔK and the fatty acid composition. The maximum extraction yield, expressed as percent of oil mechanically extracted respect to the oil content in the seeds, determined by solvent extraction, was obtained with the combination of the highest extraction temperature, the slowest screw rotation speed and seeds preheating. Under these conditions yield was 80.28±0.33% (w/w), 25% higher than the lowest yield obtained among investigated conditions. The extraction temperature and seed preheating showed a significant effect on FFA, on spectroscopic indices K232, K270 and ΔK values. The average values of these parameters slightly increased rising the temperature and in presence of preheating, the screw rotation speed did not affect the chemical characteristic tested. In the extraction conditions investigated no significant changes in PV and fatty acids composition of oil were observed.

Effect of Heating Methods on Quality Attributes of Culled Saanen Crossbred Goat Meat

The effect of boiling, grilling, and microwaving until reaching temperature of 85 °C on culled Saanen goat meat was evaluated and compared to raw samples. Biceps femoris muscle was used to evaluate the effect of these heating methods on proximate composition, collagen, cook loss, color, and texture profile analysis. Supraspinatus muscle was used to determine the effect of these heating methods on changes in peroxide value (PV) and thiobarbituric acid reactive substances (TBARS) of meat during 5 days of chilled storage. Boiled and grilled samples showed lower moisture (63.04 and 63.89 %, respectively) and higher protein (29.20 and 29.59 %, respectively) and fat (5.98 and 4.01 %, respectively) than those of the microwaved sample (68.03 % moisture, 26.72 % protein, and 2.95 % fat) (P < 0.05). Higher total collagen in the grilled sample (14.35 mg/g) and higher soluble collagen percentage (6.57 %) in the microwaved sample were obtained (P < 0.05). Boiled and grilled samples revealed higher cook loss (39.70 and 41.28 %, respectively) compared to microwaved samples (28.82 %) (P < 0.05). Grilled samples exhibited higher hardness (3,730.21 g), gumminess (2,397.76), and chewiness (1,774.71) than those of other heated samples (P < 0.05). Higher lightness (L* = 54.90), lower redness (a* = 4.11) and yellowness (b* = 13.96) in boiled sample were found (P < 0.05). Grilled samples exhibited sharper PV formation while boiled samples revealed sharper TBARS formation during storage (P < 0.05). In summary, variation in remaining moisture, soluble collagen, parallel with types of heating medium led to complexity in the results obtained in total solid, cook loss, color, and texture profile analysis (TPA). Boiled samples were prone to yield higher TBARS formation.

Effect of thermal and photo oxidation on the stability of cold-pressed plum and apricot kernel oils

Oxidative stability of cold-pressed plum (Prunus domestica) kernel oil (PKO), and apricot (Prunus armeniaca) kernel oil (AKO) were evaluated under thermal-oxidation and photo-oxidation conditions. Changes in peroxide value (PV), conjugated dienes (K232), and levels of volatile compounds in the cold-pressed oils were monitored during storage for 12 days under oxidation conditions. Under thermal oxidation conditions, PV values of PKO reached the maximum value (63.8 meq O2/kg) after 12 days of storage, while PV values of AKO reached the maximum value (54.5 meq O2/kg) after 10 days of storage. K232 values exhibited similar behavior under accelerated oxidation conditions, wherein the highest K232 values were 12.38 and 10.91 for PKO and AKO at the 12th and the 10th day of storage, respectively. Under photo-oxidation conditions, both values recorded similar behavior. At the end of storage (12th day), PV values reached 117.5 and 67.62 meq O2/kg for PKO and AKO, respectively. Similarly, the maximum K232 values were 5.72 and 4.56 for PKO and AKO, respectively. Hexanal, and E-2-heptenal recorded the values of 149.2 and 41.83 × 106 AU for the PKO after 12 days of storage under thermal oxidation conditions, while hexanal, and E-2-heptenal reach up to 199.2 and 58.88 × 106 AU for the AKO after only 10 days of storage. At the end of 12 days of storage under photo-oxidation of PKO and AKO, the aldehydes were detected as the most identified chemical group (especially hexanal, and E-2-heptenal) in the photo-oxidized PKO and AKO.

Changes in oxidation indices and minor components of low free fatty acid and freshly extracted crude palm oils under two different storage conditions.

This article reports on the changes of oxidation indices and minor components of low free fatty acid (FFA) and freshly extracted crude palm oils after storage at ambient (28 ± 1 C) and 60 C for 77 days. The changes in peroxide value (PV), FFA, extinction coefficient at 233 and 269nm (K233 and K269), bleachability index (DOBI), carotene and vitamin E contents were monitored. PV, FFA, K233 and K269 of both oil samples increased as storage progressed while the values of carotene and vitamin E contents decreased. At the end of storage period at 60°C, the carotene content of low FFA crude palm oil was 4.24ppm. The storage conditions used led to the loss of entire vitamin E fractions of both oil samples as well as a reduction in DOBI values except for freshly extracted crude palm oil stored at ambient temperature.

Effect of gelatin/agar bilayer film incorporated with TiO2 nanoparticles as a UV absorbent on fish oil photooxidation

AbstractThis research evaluated the effect of gelatin/agar bilayer film and nanocomposites containing different concentrations of TiO2 nanoparticles (0.5%, 1% and 2%) as ultraviolet (UV) and oxygen barriers on the oxidative stability of fish oil. Samples of fish oil covered with the bilayer films were stored under UV light or in darkness and with or without lids at 18 °C for 12 days. Oil quality in terms of peroxide values (PV), thiobarbituric acid (TBA), conjugated diene (CD), fatty acids profile and colour change (∆E) was monitored during storage. Fish oil photooxidation was hindered by increasing TiO2 concentration, so that nanocomposite containing 2% of the nanoparticles could control photooxidation, similar to the samples stored in darkness. Furthermore, upon studying both photooxidation and autoxidation, the highest amounts of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), as well as the lowest amount of changes in PV, TBA, CD and ∆E, were observed in oils covered with the nanocomposites.

Oil Bodies Extracted from High‐Fat and Low‐Fat Soybeans: Stability and Composition During Storage

Soybeans contain oil bodies (OBs) that encapsulate triacylglycerols (TAGs) with a phospholipid monolayer carrying scattered proteins. In nature, soybean OBs can form natural emulsions in aqueous media and may serve as natural, minimally processed, stable, and pre-emulsified oil for addition into appropriate food systems. In this study, OBs were obtained by aqueous extraction from the mature seeds of 2 soybean crop cultivars, high-fat soybean and low-fat soybeans. The compositions of the extracted OBs were analyzed during storage at room temperature up to 14 d (pH = 7). The oxidative stability of these OBs, stored at 60°C, was evaluated by measuring the presence of primary (lipid hydroperoxides) and secondary lipid oxidation products (malondialdehyde) by determining the standard peroxide value (PV) and thiobarbituric acid-reactive substances (TBARS) value. During storage, the contents of unsaturated fatty acids, phospholipids, and tocopherols declined in both OBs, while their mean particle diameters (d32 ) and ζ-potentials increased. The changes in PV and TBARS values exhibited a similar trend for both OBs, but the OBs from low-fat soybeans had significantly lower PV and higher TBARS values than the OBs from high-fat soybean cultivars (P < 0.05). Overall, the OBs from both soybean cultivars had good stability during storage.

Shelf Life of Tropical Canarium Nut Stored under Ambient Conditions

There is a need to develop alternative crops to improve the food security and prosperity of developing countries. The tropical nut Canarium indicum (canarium nut) is increasingly used as a shade tree for cocoa and has potential for commercialization as a sustainable crop that will improve food security and livelihoods in Melanesia and East Asia. There is no information on canarium nut shelf life characteristics. Canarium kernels may be prone to rancidity, due to a high content of unsaturated fatty acids. Kernels at 5.4% moisture content were vacuum-packed with a domestic vacuum-packaging system and stored for six months in Papua New Guinea and for nine months in Southeast Queensland, Australia at both ambient temperatures (22 to 31 °C and 22 to 25 °C, respectively) and under refrigeration. Nuts were analysed for changes in peroxide values and free fatty acids (FFAs) over the storage periods that might indicate development of rancidity. Peroxide values indicated very low levels of oxidation in all treatments. Free fatty acids were at low levels but increased significantly during storage at ambient temperatures. The results suggested that vacuum-packed Canarium nuts can be stored safely under ambient tropical conditions for six months with daytime temperatures around 31 °C, and for nine months at 25 °C. Increasing FFA levels at ambient temperatures indicate caution about longer storage time at ambient temperatures. Storage under refrigeration greatly prolonged shelf life.

Formation of cholesterol oxides in lipid medium during microwave heating

Microwave (MW) heating of foods may cause the formation of cholesterol oxidation products (COPs). COPs formation depends on the conditions of MW heating and the composition of the food matrix. The aim of this work was to study the formation of major COPs from cholesterol incorporated into palm, extra virgin olive, soybean, or fish oils during MW heating, and to monitor changes in peroxide value and fatty acid (FA) profiles. Model systems composed of mixtures of cholesterol and oil (2.5 mg of cholesterol/g oil), were heated for 20 min in multimode (900 W), unimode MW (≈300 W) ovens, or convection oven at 180°C. Maximum total COPs contents largely varied (46.4–250.4 µg/g lipids), depending on the type of heating system and oil matrix. Multimode MW heating caused greater COPs formation than unimode MW. COPs formation trends in the conventional oven were similar to those of MW heating, except for fish oil. Results indicated that soybean oil, compared with the other oils tested, did not promote cholesterol oxidation during MW heating, while the opposite trend was observed for extra‐virgin olive oil and palm oil. FA profile and natural antioxidants influenced cholesterol and surrounding media oxidation during MW heating.Practical applications: This work explores the formation of oxysterols by microwave heating in model systems. This will help assess the possible risks for formation of these compounds during industrial and home cooking practices.Microwave (MW) heating of foods may cause formation of cholesterol oxidation products (COPs). In this work, a model system consisting of four types of edible oils with added cholesterol was employed and heated with three different forms (unimodal and multimodal MW, and conventional heating) for different time periods. Generation of COPs in all the model systems was monitored.

Storage stability of maize-groundnut composite flours and an assessment of aflatoxin B1 and ochratoxin A contamination in flours and porridges

Defatting of groundnut flour used for composite development can not only improve nutritional quality of its products but also the storage stability. Maize, groundnut and their composite (full fat and defatted) flours were prepared and stored at room temperature over a period of 3 months. Storage stability of these products was assessed based on changes in water activity, peroxide value (PV), free fatty acids (FFA), thiobarbituric acid (TBA), microbiological profiling and levels of mycotoxins that included aflatoxin B1 (AFB1) and ochratoxin A (OTA). Overall results revealed that the rate of change of PV, FFA and TBA significantly (p ≤ 0.05) increased with increasing storage time, which was highest for full fat flours than in the defatted flours. For example, PV of the FFG and DFG were respectively, 0.88 and 0.40 mEq/kg, meanwhile TBA was 4.53 and 2.71 mg malonaldehyde/kg. There was a much higher rate of increase in FFA (%) with increasing storage time in full fat and composite flours when compared to that of their defatted counterparts. Generally, microbiological data demonstrated an increase in total microbial counts during storage in these foods possibly resulting in mycotoxins, AFB1 (range: 9.08–38.48 μg/kg) and OTA (range: 0.33–19.50 μg/kg) in all samples with groundnut and maize having the highest contamination levels. A 127.8% increase in OTA level was noted when maize flour inclusion level in the full fat composite increased from 55 to 85%, but only a 24.7% increase in OTA level was noted in defatted composites during storage. Reducing the inclusion level of groundnut flour, the main source of AFB1 as found, resulted in a drastic reduction in AFB1 level in full fat and defatted composite flours by 54.1 and 76.4%, respectively, during storage. The findings highlight that shelf life stability of composites can be maintained upon defatting during the fortification process. It can therefore, be inferred that monitoring quality and safety of the raw materials as well as that of the final products during storage is crucial.

The Effects of Liposomal Encapsulated Thyme Extract on the Quality of Fish Mince and Escherichia coli O157:H7 Inhibition During Refrigerated Storage

ABSTRACTThe effects of liposomal encapsulated and unencapsulated (0.3 and 0.5% w/w) thyme extract (TE) on the quality of silver carp (Hypophthalmichthys moltrix) mince during chilled storage (4 ± 1°C) were examined over a period of 15 days. The samples were analyzed by microbiological (total viable count, psychrotrophic count) and chemical (peroxide value and total volatile nitrogen) experiments. Also, the efficacy of the encapsulated extract in control in the population of Eschershia coli O157:H7 inoculated in silver carp mince was investigated. Results showed that the samples containing 0.5% of encapsulated thyme had fewer changes in peroxide value and total volatile nitrogen in comparison to other treatments (p < 0.05). Encapsulated thyme also could inhibit the growth of mesophilic and psychrotrophic bacteria in the samples compared to the control and the samples containing unencapsulated extract during the storage period. Moreover, 0.5% encapsulated TE reduced the population of E. coli O157:H7 below the acceptable level (< 2) from Day 9 until the end of the storage period. In conclusion, the results obtained from this study suggest that liposomal encapsulation may help to obtain higher antimicrobial activity in lower TE concentrations in minced fish.

Changes in lipid oxidation and related flesh qualities of white shrimp (Litopenaeus vannamei) during iced storage: Effects on the use of increasing ozone exposures

For the first time, changes in lipid oxidation (peroxide value [PV], para‐anisidine value [p‐AnV], and total oxidation [Totox]) and related flesh qualities (titratable acidity [TA], water retention index [WRI] as well as volatile amines of total volatile basic nitrogen [TVB‐N], and trimethylamine nitrogen [TMA‐N]) of farm‐raised white shrimp (Litopenaeus vannamei) during iced storage of up to 11 days as affected by increasing ozone exposures were performed. Both fresh and ice‐stored sample situations were submitted to ozone exposures. Domestic facility commercially available that discharged ozone safely specifically was employed. Results indicated that PV, p‐AnV, Totox, and temporal PV/p‐AnV parameters at both ozone treatment situations would persist during the investigated storage. Increasing ozone exposures brought about some decreases in p‐AnV, Totox, and TVB‐N but less reliably in PV and TMA‐N. Most affected lipid oxidation and related flesh quality parameters would probably be p‐AnV and TVB‐N, respectively. Besides, the trends of TA and WRI over time seemed unclear. In this study, the domestic ozone facility appears promising to improve the quality of shrimp during iced storage. To help establish the ozone treatment approach that would improve the overall quality shelf of processed shrimp, further studies that involve other analyses such as browning development and sensorial acceptance are warranted and applicable to other economically important crustacea species.Practical applications: Domestic facilities that safely discharge ozone for home use are increasingly marketed in many parts of the globe. On the other hand, lipid oxidation although responsible for rancidification and a process that significantly deters the overall fish product quality, remains among the many cold/iced storage concerns. Herein via domestic facility, increasing ozone exposures safely discharged onto farm‐raised shrimp has allowed for the study of lipid oxidation and related flesh qualities of processed samples during iced storage. This is the first report to demonstrate that increasing ozone exposures applied either on fresh and or ice‐stored shrimp situation(s) would result in different changes in PV, p‐AnV, Totox, TA, WRI, TVB‐N as well as TMA‐N. The data provided herein reveals the use of domestic ozone facility as promising candidate towards food safety, and increases both knowledge and understanding concerning changes in lipid oxidation and related flesh attributes of ozone‐treated crustacea.During iced storage of up to 11 days, the evolution of tested parameters of ozone‐treated shrimp as it was affected by increasing ozone exposures showed that for lipid oxidation, the p‐anisidine value (p‐AnV) would appear the most affected probably because it would increase at a much faster rate to generate many secondary oxidation products fairly before the peroxide value (PV) attained the propagation reactions/periods. With respect to related flesh qualities, total volatile basic‐nitrogen (TVB‐N) would appear the most affected over the others namely, trimethylamine nitrogen (TMA‐N), titratable acidity (TA) as well as water retention index (WRI). Moreover, the TA might show a rather decreasing tendency. Amid the wave‐like pattern of TA and WRI that reflect the anticipated fluctuations/trends, the different measurement units of all these parameters put together can be apparently gauged by some proportional estimate.

Effects of Cinnamon (Cinnamomum Verum) Extract on Functional Properties of Butter

Butter is a dairy product made by churning fresh or fermented cream or milk. It is generally used as a spread and as an ingredient in cooking purposes. The incorporation of natural ingredients with health benefits into butter is one way to increase its intake. The potential health benefits of cinnamon (Cinnamomum verum) derived primarily from bioactive ingredients such as antioxidants, polyphenols and flavonoids. The objective of the present study was to improve the quality of butter made from cream with the addition of cinnamon extract. Milk cream with 36% fat was churned at 10oC to maintain the fat at high level with low moisture content. Based on preliminary investigation, soxhelt extraction of cinnamon quills was carried out with 39% (v/v) ethanol. Butter was prepared by incorporating cinnamon extract into butter at 1, 3, and 5% (w/w). Sensory evaluation was done using 20 semi trained panelists based on 5 point hedonic scale. It was found that cinnamon extract can be incorporated in to the butter formulation up to 3% (w/w) without compromising the sensory attributes. It was subjected to further analysis with 1000ppm potassium sorbate added butter. Changes in peroxide value, free fatty acids value and pH were monitored at weekly intervals. Microbiological studies (Total plate count and yeast and mold) were done at two weeks interval during two months storage period. Storage stability was tested at refrigeration (4oC) condition. Total phenolic content and free radical scavenging activity of the 3% cinnamon extract incorporated butter were 135.62±1.00μg GAE/mg and 38.73±0.01% DPPH, respectively. The cinnamon extract incorporated butter has shown low levels of peroxide value, free fatty acids value and low microbial count when compared to ordinary butter (without adding preservative) and potassium sorbate added butter. Antioxidant activity of cinnamon extends the shelf life of butter. This study demonstrates the 3% cinnamon extract can be used to formulate an antioxidant rich butter and it can be placed as a natural preservative for preparation of butter.

Refining Ostrich Oil and its Stabilization with Curcumin

Ostrich Oil is particularly known for its cosmetic and therapeutic use. Being rich in polyunsaturated fatty acids, it is prone to oxidation causing undesirable changes in peroxide value, color, flavour and odor, which deteriorates its nutritional value. The objective of the study is to establish an efficient separation method to refine ostrich oil and stabilize it with curcumin or the extract of Curcuma longa. The reduction in peroxide value, color intensity, moisture content and odor were used as indicators of the purity of the oil. The modified refining process developed saw a reduction of 75% free fatty acid, 90% peroxide value, 54% moisture content, 60% in color intensity and odor. Curcumin, a natural antioxidant, prevented lipid peroxidation by 56% while vitamin E by only 8%, when tested at the same concentration (0.04%). Curcumin proved to be an effective stabilizer in a 6-month accelerated stability test. This study presents a method to refine ostrich oil efficiently and the ability of a natural antioxidant, curcumin, to stabilize the refined ostrich oil.This simple and straight forward method to refine and stabilize the oil can be adapted to be used for any ratite oils. The use of a natural alternative, curcumin as the anti-oxidant is not only safe but provides further added health benefits.

Effect of natural antioxidants and modified atmosphere packaging in preventing lipid oxidation and increasing the shelf-life of common dolphinfish (Coryphaena hippurus) fillets

We investigated the effects of natural antioxidants and modified atmosphere packaging (MAP) on the quality and shelf-life of Coryphaena hippurus (common dolphinfish) fillets. Fillets of the control group (CO) were simply placed on trays and not sealed. Fillets of the second group (MAP) were preserved in modified atmosphere (45% CO2, 50% N2, 5% O2), and fillets of the third group (MAP-AOX) were preserved by combining natural antioxidants from halophytes with modified atmosphere. All samples were stored in a refrigerator at −1±0.5 °C for 18 days. Analyses were conducted at T0 and after 3, 6, 12, 15 and 18 days of storage. According to sensory tests and colour analyses, the fillets in the MAP and MAP-AOX groups maintained the best appearance. In the CO group, we observed a significant decrease of omega-3 polyunsaturated fatty acids (FAs) (P < 0.05), which indicates the oxidation of these FAs. FAs in the MAP and MAP-AOX groups were protected against oxidation. Further, lower peroxide value (PV) and malondialdehyde (MDA) content were observed in the MAP and MAP-AOX groups compared to the CO group. The sensory properties of the fillets were correlated with changes in FA content, PV and MDA content.

Property Prediction of Dry Common Carp (Cyprinus Carpio) During Storage by Kinetic Model

Abstract Common carp (Cyprinus carpio) is an important food resource in European and Asian countries. Nowadays, common carp after drying process is appreciated by the transportation agency and food industry because of its low transportation cost. Changes of acid value (AV), total bacterial count (TBC), and peroxide value (PV) were reported in this study. We found that the changes of AV, TBC and PV of dry common carp fitted the first order reaction model and the reaction energies of changes of AV, TBC, and PV during storage were 4.56 kJ/mol, 2.21 kJ/mol, and 2.33 kJ/mol, respectively. This study will provide theoretical knowledge to food factories relating with dry fish storage and transportation.

A predictive model of acrylamide formation influenced by moisture content, lipid oxidation, and methylglyoxal in fried potato slices

Acrylamide (AA) is known to be a neurotoxic, genotoxic and carcinogenic compound, which is classified as a probable human carcinogen. The main purpose of this paper was to study the changes in peroxide value (PV), p-anisidine value (PAV), methylglyoxal (MG), and moisture content (MC) in potato slices fried at different temperatures and lengths of time. The determination of AA was carried out using HPLC-MS/MS. Our results showed that AA formation was obviously influenced by MG content and PV; the AA content increases with the increase of PV and MG. The contribution of PV and MG to AA formation was included in a prediction model that could be used as a tool to predict the formation of AA in potato slices, and the model was as follows: AA = −0.200–0.001 × MC + 0.330 × PV + 0.074 × PAV + 0.103 × MG. The predicted AA content value was in good agreement with the actual AA content.

Evaluating and Predicting the Oxidative Stability of Vegetable Oils with Different Fatty Acid Compositions

The aim of this research was to evaluate the oxidative stabilities and qualities of different vegetable oils (almond, blend 1-8, camellia, corn, palm, peanut, rapeseed, sesame, soybean, sunflower, and zanthoxylum oil) based on peroxide value (PV), vitamin E content, free fatty acid, and fatty acid composition. The vegetable oils with different initial fatty acid compositions were studied under accelerated oxidation condition. It showed that PV and n-3 polyunsaturated fatty acid (PUFA) changed significantly during 21 d accelerated oxidation storage. Based on the changes of PV and fatty acid composition during the oxidation process, mathematical models were hypothesized and the models were simulated by Matlab to generate the proposed equations. These equations were established on the basis of the different PUFA contents as 10% to 28%, 28% to 46%, and 46% to 64%, respectively. The simulated models were proven to be validated and valuable for assessing the degree of oxidation and predicting the shelf life of vegetable oils.

California Almond Shelf Life: Lipid Deterioration During Storage

The effects of storage conditions on the lipid deterioration in California almond nuts and sliced were studied. Natural whole almonds with or without polyethylene (PE) packaging and blanched whole almonds and sliced with PE packaging were stored in 10 different storage conditions which were combinations of different temperatures and relative humidity levels. The peroxide values (PVs), iodine values (IVs), and free fatty acids (FFAs) were monitored during the storage. The PVs in the natural samples did not change noticeably whereas the blanched samples changed greatly, indicating that skins may have played a significant role. The IVs decreased slightly in the 1st 150 d of storage and then leveled off. The slightly faster changes in IVs in the blanched samples coincided with the greater changes in PVs in the blanched samples. The natural samples exhibited much higher FFA levels than the blanched samples after storage. In general, FFA increased with increasing storage time, temperature, and humidity. Highest levels of FFA were observed in the samples stored at high temperature and high humidity. The results reported in this article provide useful information that almond producers and processors could use to develop their storage and transport processes.

Effect of electron beam irradiation on quality indicators of peanut butter over a storage period

Electron beam (e-beam) irradiation is an effective non-thermal processing step for the reduction of Salmonella in peanut butter. The objective of this study was to evaluate the effects of e-beam irradiation on quality indicators of peanut butter. Peanut butter samples were exposed to a range of e-beam doses and examined over a 14-day period at 22°C. Colour analysis (L∗, a∗, b∗), spreadability, peroxide values (PV) and thiobarbituric acid reactive substances test (TBARS) for lipid oxidation were monitored, fatty acid and amino acid profiles were verified and protein degradation was determined by sodium dodecyl sulphate–polyacrylamide gel electrophoresis (SDS–PAGE). Changes in colour, PV, and TBARS were observed as e-beam dose increased. No significant changes in spreadability were observed (P>0.05). When applied to peanut butter, e-beam irradiation will produce significant changes in quality indicators; future studies should include sensory evaluation and consumer acceptance studies.