Frozen Storage Time Research Articles

Comparison of Pork Quality in Different Frozen Storage Time and Its Change Mechanism

In order to understand the possible reasons and mechanisms of pork quality changes in frozen storage, the quality indicators such as water holding capacity, texture and color were tested to pork for 4 months and 8 months of frozen storage. The type and distribution of moisture in pork samples were detected by low-field nuclear magnetic resonance (LF-NMR), and the correlation between different water distribution and water holding capacity, texture was explored. The changes in pork flavor components and the types of characteristic substances were discussed by the electronic nose and lipidomics analysis based on the time-of-flight mass spectrometer. The results showed that the quality of frozen pork for 8 months significantly deteriorated, and the morphology of the muscle fibers was looser, the water relaxation time was delayed, the peak area was reduced, compared with pork frozen for 4 months. The quality indicators such as water holding capacity and texture of pork were positively correlated with frozen storage time, and negatively correlated with moisture relaxation time and peak area, which also indicated that the main reason for the deterioration of pork texture after a long period of freezing storage might be including the migration and loss of bound water and non-flowing water in pork. The partial least square regression analysis (PLS-DA) of pork electronic nose data found that the flavor components of pork also changed significantly after long-term frozen storage. The changed flavor components were mainly alkanes, aromatic components, weakly polar compounds, methane, and alcohol compounds. The identification of five different compounds related to oxidation by high-resolution mass spectrometry indicated that the significant changes in pork flavor might be caused by the oxidation of lipids in muscle tissue after a long period of freezing storage.

Shelf-Life Prediction of Glazed Large Yellow Croaker (Pseudosciaena crocea) during Frozen Storage Based on Arrhenius Model and Long-Short-Term Memory Neural Networks Model

In this study, the changes in centrifugal loss, TVB-N, K-value, whiteness and sensory evaluation of glazed large yellow croaker were analyzed at −10, −20, −30 and −40 °C storage. The Arrhenius prediction model and long-short-term memory neural networks (LSTM-NN) prediction model were developed to predict the shelf-life of the glazed large yellow croaker. The results showed that the quality of glazed large yellow croaker gradually decreased with the extension of frozen storage time, and the decrease in quality slowed down at lower temperatures. Both the Arrhenius model and the LSTM-NN prediction model were good tools for predicting the shelf-life of glazed large yellow croaker. However, for the relative error, the prediction accuracy of LSTM-NN (with a mean value of 7.78%) was higher than that of Arrhenius model (with a mean value of 11.90%). Moreover, the LSTM-NN model had a more intelligent, convenient and fast data processing capability, so the new LSTM-NN model provided a better choice for predicting the shelf-life of glazed large yellow croaker.

Freeze-thaw stability of emulsions made with native and enzymatically modified egg yolk fractions

Frozen storage of food emulsions can increase their tenability and create possible applications in frozen food products. However, coalescence and phase separation can occur during freezing/thawing. In order to assess options for mitigating freeze/thaw-destabilization, egg yolk's emulsifying functionality in the form of whole egg yolk and its granula and plasma fractions was investigated. The fractions were enzymatically pretreated (phospholipase A2) and their emulsifying functionalities were assessed in dependence of pH, salinity, freezing velocity and frozen storage time with oil droplet size and phase separation as measures. Mayonnaise-type oil in water emulsions of sunflower oil were prepared at pH 3, 4 and 6.5 with a salt content of 0.15 and 0.55 M NaCl with a colloid mill. The emulsions were frozen to −20 °C with varying freezing rates and stored up to 24 h. Egg yolk and plasma stabilized emulsions showed higher freeze/thaw stabilities than granule stabilized emulsions. Enzymatic treatment increased the stability of emulsions prepared with egg yolk and granula, but decreased the stability for plasma stabilized emulsions. The destabilization increased with longer frozen storage time. Very slow or fast freezing velocity resulted in higher destabilization effects than an intermediate freezing rate at low salt content. Increasing salinity from 0.15 to 0.55 M NaCl as well as increasing pH from 3 to 6.5 resulted in more stable emulsions and highest destabilization at the highest freezing rate.

Effect of part-baking time, freezing rate and storage time on part-baked bread quality

In the baking industry, different processes and methods of freezing have been used for breadmaking to preserve a quality comparable to that of fresh bread. In this study, the effect of part-baking time, freezing rate, and frozen storage time on part-baked French bread quality was determined. The bread was part-baked for 0, 3 and 6 min, frozen at slow (0.15 °C/min) and fast (1.75 °C/min) freezing rates, stored under freezing conditions for up to 56 days and thawed every 14 days. Part-baked bread was rebaked, and the SV and firmness at 2, 24 and 48 h were obtained. An experiment with a factorial design of 3×2×5 (3 part-baking time, 2 freezing rates and 5 frozen storage times) with analysis of variance (ANOVA) at a confidence level of 95% was carried out. The highest SV was ​​obtained at 6 min of part-baking at a slow freezing rate and decreased as the frozen storage time increased. In contrast, TPA showed that bread firmness increases when the specific volume decreases, and the highest firmness is at 0 min of part-baked time. Relatively long part-baking times allow for firm crumb formation with limited damage to the structure and therefore bread with optimal quality.

Effect of High-Pressure Processing and Frozen Storage Prior to Canning on the Content of Essential and Toxic Elements in Mackerel

The mineral content of canned (115 °C, 45 min; Fo = 7 min) Atlantic Chub mackerel (Scomber colias) previously subjected to different high-pressure processing (HPP) (200, 400, and 600 MPa for 2 min) conditions and frozen storage times (3, 10, and 15 months at −18 °C) was studied. Prior processing steps modified extensively the contents of essential and toxic elements, so that substantial changes were produced in canned fish. Thus, canned mackerel showed higher levels of most essential (Na, Ca, Fe, Co, Cu, Se) and toxic (Sn, As) elements when compared with initial raw fish; contrary, some essential (K, Mg, P) and toxic (Pb) elements revealed lower values in canned samples. HPP led to increased levels of essential (S, Se) and toxic (Cd) elements; the opposite effect was produced on Ca and Mn (essentials) and Ba (toxic) elements. Scarce effects of frozen storage time could be concluded; remarkably, storage time increase led to increased Ca and Mn levels, while produced decreases of K, Cd, and Pb contents. Changes in essential and toxic element contents are explained on the basis of protein denaturation, protein and lipid breakdown, water and liquor losses from the fish muscle, and muscle interaction with brine-packaging medium.

Impact of frozen storage duration of raw pork on the formation of advanced glycation end-products in meatballs

Advanced glycation end-products (AGEs) are harmful compounds produced during food processing. This study investigated the effects of frozen storage duration (−18 °C) of raw pork on AGEs generation in meatballs. Meatballs were prepared using frozen raw pork (at 0, 30, 60, 90, and 120 days), and Nε-(carboxymethyl)lysine (CML)/Nε-(carboxyethyl)lysine (CEL) (typical AGEs) levels were determined. With increasing frozen storage times of raw pork, CML levels in meatballs increased from 13.26 (0 day) to 43.30 mg/kg protein (120 days), and CEL levels increased from 12.37 (0 day) to 40.50 mg/kg protein (120 days). Furthermore, oxidative damage to raw pork (carbonyls, total sulfhydryl groups, free amines, surface hydrophobicity, thiobarbituric acid-reactive substances of residual lipids, and intrinsic tryptophan fluorescence intensity) was assessed during storage periods. A significant correlation between myofibrillar protein oxidation and CML/CEL levels was observed, suggesting that oxidative damage to raw pork during frozen storage could promote the generation of CML and CEL in meatballs. Therefore, controlling myofibrillar protein oxidation in raw pork may facilitate reduced AGEs levels in meatballs.

Liquid loss in thawed cod—Deconvoluting the effects of freezing‐rate, freezing cycles, frozen storage time, and thawing‐rate through a full factorial design

AbstractFish is a highly perishable product and freezing is the obvious way to increase shelf life. The freezing process involves the initial freezing, a frozen storage period and thawing—all of which influence the quality of the end product. In this study, the quantity of liquid loss is used as an indication of the structural damage induced by these processes. A full factorial experiment design addresses the effects of freezing and thawing rates (fast vs. slow), number of freezing cycles (1 vs. 2) and frozen storage (1 year vs. 1 week). The results show strong evidence that fast processes of freezing and thawing reduce the subsequent liquid loss. However, 1 year frozen storage at −20°C induces high liquid loss independently of the freezing and thawing rates. Adding a second freezing cycle also adds to the liquid loss upon final thawing. By increasing the number of processing steps (additional freezing cycles) the strain put upon the samples progressively increases. This leaves samples at the end of long sequences of processing especially sensitive to damage caused by ice crystals. In this way, the thawing protocol might be of high importance, especially during the last freezing cycle of twice frozen samples.Practical ApplicationIn order to minimize liquid loss through production of frozen seafood, it is imperative that producers use the best practice at every stage. Liquid loss influences yield through production, but it also contributes to quality parameters relevant to both producers and consumers. Every stage of the production impacts liquid loss, and examining and classifying the different processing steps separately is the common approach to assess the effect. For the final product however, the impact of one isolated step is entangled in the combined effect off all the different processing steps. In this study, we have examined the processing continuum from the first freezing to the last thawing, including the effects of an extra freeze cycle and frozen storage period. In this way, we demonstrate the risk of pitfalls through such processing and also highlight the process combinations that are synonymous with low liquid loss.

Molecular mechanism of protein dynamic change for Hengshan goat meat during freezing storage based on high-throughput proteomics

As traditional frozen storage leads to the degradation of meat quality, elucidation of dynamic change mechanism is urgently needed. Proteomic differences in postmortem frozen storage time (0, 30 and 60 days) of Hengshan goat meat at −18 °C were studied by label-free proteomics based on high resolution quadrupole-Orbitrap mass spectrometry. A total of 492 proteins were identified, of which 485 proteins were quantified, and the difference of 199 proteins was observed. The analysis of the differentially expressed proteins related to quality observed that triosephosphate isomerase and peroxiredoxin-6 were potential biomarkers for goat meat discoloration. Troponin and myosin can represent the tenderness of goat meat. Heat shock protein 70 can be used as water-retaining proteins in goat meat. Bioinformatics analysis suggested that the distinguishingly expressed proteins were involved in glycolysis and the ubiquitin–proteasome pathway revealing that the strong degradation of proteins, which cause of the degradation of long-term frozen meat quality. These results could enrich and beyond the existing knowledge of frozen meat, expecting to have a further understanding of the changes of meat quality at the molecular level.

Comparative study of the impacts of conventional freezing and dehydrofreezing on apple fruit quality during storage

The present study deals with the impact of storage time on the quality of dehydrofrozen versus conventionally frozen apple. Samples were submitted to freezing as fresh fruit or following the first stage of air drying. The quality was evaluated along a freezing storage period of 18 months under -18 °C. Thaw exudate water (TEW), total colour difference (TCD), and total polyphenol content (TPC) of dehydrofrozen/thawed samples were assessed regarding the water content (W) versus the frozen storage time (FST) (0-18 months). Dehydrofreezing exhibited significant effects on TEW and TCD of dehydrofrozen/thawed apples. Indeed, the lower the W, the lower the TEW content and TCD of partially dried frozen/thawed samples. TPC losses were significant for samples without any pre-dehydration stage and decreased when initial water content decreased. The 18-month frozen storage at -18 °C had the most insignificant effects on all quality response variables for the previously most dried samples. Thus, adequate drying of fruit before freezing is a relevant way to maintain the stability of fruit quality during long-term storage.

Impact of prior high-pressure processing on lipid damage and volatile amines formation in mackerel muscle subjected to frozen storage and canning

This research describes a first approach to analyse the effects of using high-pressure processing (HPP) as a pre-treatment before frozen storage and subsequent canning of fish. For it, Atlantic Chub mackerel (Scombercolias) was subjected to HPP (200, 400 and 600 MPa for 2 min) followed by freezing (−30 °C for 48 h), frozen storage (−18 °C for 0, 3, 6, 10 or 15 months), canning and canned storage (3 months at 20 °C). Lipid damage development (hydrolysis and oxidation) and volatile amines formation (total and trimethylamine) were determined in canned mackerel. As a result, a marked inhibitory effect (p < 0.05) on free fatty acids content was observed in canned mackerel previously subjected to different frozen storage times. This effect increased with pressure applied. Furthermore, higher average polyene values were obtained in most canned fish previously subjected to any high-pressure treatment when compared with Control canned fish. No effect (p > 0.05) on thiobarbituric acid reactive substances and trimethylamine values was noticed related to HPP. However, increasing (p < 0.05) peroxides and fluorescent compounds contents were obtained when applying the two highest pressure levels.

Evaluation of porcine skin layers separation methods, freezing storage and anatomical site in in vitro percutaneous absorption studies using penciclovir formulations

Literature reveals high variation in the techniques used for in vitro studies of percutaneous absorption, resulting in several outcomes and making it difficult to establish a correlation with in vivo absorption. This paper investigates the role of the main parameters that may influence on the penetration/permeation profile of penciclovir as a model drug, from a conventional (cream) and an innovative formulation (hydrogel nanoemulsion) in porcine skin. The parameters evaluated were: the separation method of skin layers after contact with formulation, the penetration and permeation skin capacity according to frozen storage time (up to three months of storage) and the evaluation of different anatomical sites (abdomen and ear). Concerning the separation method of skin layers, this study showed that, for both products, there was a drug loss when the hot water immersion classic technique was employed. Regardless of the anatomical site, there was no significant difference for the penetration and permeation for both formulations between the non-scalded abdomen and ear skin. Finally, it was confirmed that porcine skin permeability does not vary significantly with frozen storage for up to 30 days. Our findings provide new understandings about the parameters addressed and will further stimulate their application as an important knowledge for in vitro percutaneous studies.

Understanding the structural, pasting and digestion properties of starch isolated from frozen wheat dough

The multi-scale structure and physicochemical properties (e.g., pasting and digestion features) of starch isolated from native and frozen dough (storage at −18 °C for 10, 20 and 30 days, respectively) were investigated with combined analytical methods. Differential scanning calorimetry revealed increased freezable water contents as the extension of frozen storage time. Results showed that frozen storage treatment disrupted the granular structure but increased the particle size and ordered degree of semi-crystalline lamellae system involving lamellar structure, crystalline structure, short-rang ordered molecular structure and helical structures. And these multi-scale structural alterations were more obvious with the storage time increasing. As for gelatinization and pasting properties of frozen starches, it reflected an improved thermal-stability (e.g., increased Tc and pasting temperature) and decreased viscosity parameters such as peak and final viscosity, which may be due to the rearrangement and ordered packing of starch molecular chains during frozen storage. However, the frozen storage treatment caused increased digestibility of wheat starch by promoting the access and binding of enzymes to starch. Therefore, these results extended the knowledge of starch microstructures and technological properties during frozen storage, which may be beneficial to promote better preservation of frozen foods.

Efek Lama Penyimpanan Semen Beku Sapi Bali pada Pos Inseminasi Buatan terhadap Membran Plasma, Tudung Akrosom Utuh, dan DNA Spermatozoa

The purpose of this study was to determine the effect of frozen storage time for Bali Bull in artificial insemination station in Samarinda City, East Kalimantan on the quality of motility, viability, velocity, abnormality, plasma membrane integrity (MIn), acrosome integrity (AIn), and DNA damage of spermatozoa. The study design used a completely randomized design (CRD) with 5 treatments (storage time) and 5 replications. Frozen semen of Bali Bull used in 2009 (10 years of storage), 2011 (7 years of storage), 2013 (5 years of storage), 2015 (3 years of storage), and 2017 (1 year of storage). The storage time of frozen semen stored for one to ten years in liquid nitrogen at the artificial insemination station in Kota Samarinda, East Kalimantan was still suitable for use in artificial insemination based on motility quality (44.99±2.40%), viability (55.33±2,60%), velocity (0.050±0.002 mm/sec), abnormality (12.87±1.09%), plasma membrane integrity (58.83 ± 1.86%), acrosome integrity (75.48 ± 1 , 61%), and DNA damage of spermatozoa (1.60 ± 0.21%).

Decrease Quality during Storage Packaged Beef Sausage Edible Coating by Durian Seeds Starch-Chitosan with the Addition of Kesum Leaf Extract

This study aimed to determine the effect of the type of packaging and frozen storage time of beef sausage on the decrease in the quality of beef sausage in edible coating durian-chitosan seed starch with the addition of kesum leaf extract. The study was conducted using the factorial completely randomized design experimental method with 2 treatment factors. The first factor is the type of sausage packaging consisting of 3 levels and second factor is storage time consisting of 5 levels. The results showed the type of packaging treatment, storage time, and interaction had a significant effect on TBA but no significant effect on pH. Kesum Leaf Extract can reduce the process of lipid oxidation in sausages that are treated with edible coatings with Kesum Leaf Extract (K2) and had average 0,21–0.48 mg malonaldehyde/kg.

Changes on enzymatic activity and on sarcoplasmic and myofibrillar proteins of frozen‐stored hake (Merluccius merluccius) pre‐treated by high pressure

SummaryHigh‐pressure (HP) pre‐treatments were applied on European hake (Merluccius merluccius) followed by a frozen accelerated experiment (−10 °C). A central composite design ranging pressure levels (150–450 MPa) and frozen storage time (0–150 days) was used, being evaluated the enzymatic activities and muscle proteins. Acid phosphatase and calpain activities decreased after 150 days of frozen storage (58%/56% and 38%/56% for non‐/HP‐treated samples, respectively). Cathepsin B showed higher reductions (98%) for longer storage times. Furthermore, HP and frozen storage did not affect significantly cathepsin D activity, only slightly decreasing at 169 MPa. Furthermore, HP seemed to not affect myofibrillar proteins, while sarcoplasmic proteins were clearly affected by HP and frozen storage time, resulting in a reduction of about 53% or 23% for 431 or 450 MPa, respectively. Thus, HP could be used to lowering the deleterious effect of proteases on frozen European hake.

The effect of freezing rate, frozen storage time and thawing methods on the concentration of thymosin proteins in pork meat

Proteins are the most important ingredients in meat. They are found in meat in different forms and with different functions. Thymosins are small proteins present in many animal tissues, with molecular weights of 1000–15000 Da. The technological processing of meat causes changes in the amount and shape of the basic ingredients. During the freezing of meat and its storage in the frozen state, various chemical reactions take place causing changes in the proteins. The aim of this paper was to examine the influence of the freezing rate and thawing methods on the changes and behaviour of thymosin proteins in pork meat (M. longissimus thoracis et lumborum) during storage. Protein analyses were performed using capillary gel electrophoresis (CGE) and the SDS-MW Analysis Kit (Beckman Coulter). The meat samples were frozen at 10 different rates (from 0.23 cm/h to 1.43 cm/h). The samples were tested at different times during 60 days of storage at -20oC (after 1, 15, 30, 45, 60 days). Before the analysis, the samples were thawed in the refrigerator, at room temperature and in the microwave. After one day of storing frozen meat samples, the relative concentration of thymosin was less than 1% in all tested samples. During 60 days of storage, most samples had a slight increase in the relative concentration of thymosin. The highest relative concentration of thymosin after 60 days of storage (1.67%) was recorded in a meat sample that was frozen at a rate of 1.10 cm/h and thawed in a microwave oven.

Changes in Microbiota Profiles After Prolonged Frozen Storage of Stool Suspensions.

Introduction: Fecal microbiota transplantation (FMT) is recommended as safe and effective treatment for recurrent Clostridioides difficile infections. Freezing the FMT preparation simplifies the process, allowing a single stool sample to be used for multiple receivers and over an extended period of time. We aimed to assess the effect of long-term frozen storage on bacterial taxonomic profiles of a stool suspension prepared for FMT.Methods: DNA was extracted from a stool suspension before freezing and sequentially during the 18-month storage period at −80°C. Two different protocols were used for DNA extraction. The first relied on a classical mechanical and chemical cell disruption to extract both intra- and extracellular DNA; the second included specific pre-treatments aimed at removing free DNA and DNA from human and damaged bacterial cells. Taxonomic profiling of bacterial communities was performed by sequencing of V3–V4 16S rRNA gene amplicons.Results: Microbiota profiles obtained by whole DNA extraction procedure remained relatively stable during frozen storage. When DNA extraction procedure included specific pre-treatments, microbiota similarity between fresh and frozen samples progressively decreased with longer frozen storage times; notably, the abundance of Bacteroidetes decreased in a storage duration-dependent manner. The abundance of Firmicutes, the main butyrate producers in the colon, were not much affected by frozen storage for up to 1 year.Conclusion: Our data show that metataxonomic analysis of frozen stool suspensions subjected to specific pre-treatments prior to DNA extractions might provide an interesting indication of bacterial resistance to stress conditions and thus of chances of survival in FMT recipients.

Effect of freezing methods, frozen storage time, and thawing methods on the quality of mildly cooked snow crab (Chionoecetes opilio) clusters

Mildly cooked snow crab clusters were subjected to three freezing methods (in brine, in still air, and in circulating air), two frozen storage times (72 h and 6 months), and two thawing methods (in air and in circulating water) followed by refrigerated storage. The clusters were evaluated for weight changes during freezing, frozen storage and thawing as well as for drip loss and melanosis during the refrigerated storage. Both the freezing method and the frozen storage time significantly affected the weight changes (P < 0.001) and drip loss (P < 0.015), likely due to differences in the protein denaturation and crystallization phenomena related to the rates of freezing and thawing. Freezing in brine allowed the least weight loss during the freezing process whereas freezing in circulating air followed by short frozen storage and thawing in air minimized the weight loss during the frozen storage and thawing process. The melanosis was significantly affected by both the freezing and the thawing method (P < 0.001) in the case of short frozen storage, whereas for long frozen storage, only the effect of the freezing method was significant. To minimize melanosis, the clusters should be frozen in brine and thawed in water.

Influence of frozen storage time and thawing methods on the microflora of thawed Nile tilapia fillets

This study was aimed to find out the influence of frozen storage time and thawing methods on the counts of coliforms, E. coli, Pseudomonas spp., and total viable counts (TVC) of thawed de-skinned Nile tilapia (Oreochromis niloticus) fillets. Individual quick frozen fillets of size 120-170 g, packed in polyamide packs (2 fillets/pack), were stored at -18 ± 2 °C. Samples were taken for thawing experiments every month (months 0, 1, 2, … and 8). Four different defreezing environments, namely cold air (7 ± 1 °C), air at ambient temperature (30 ± 1 °C), cold water (8 ± 1 °C), and water at normal temperature (25 ± 1 °C), were investigated. All experiments were triplicated. No E. coli was detected in all thawed samples. No differences (p > 0.05) were observed in coliforms, E. coli, Pseudomonas spp., and TVC of the newly stored samples (month 0) after thawing by the four studied methods. No significant effects (p > 0.05) of storage time (months 1, 2, and 3) and thawing methods on the coliforms and Pseudomonas quantity of tilapia fillets were found. Thawing by cold air showed to be the most suitable mean, which resulted in significantly lower TVC (p < 0.05) compared to defrosting in ambient air or in water at normal temperature. Meanwhile, air at ambient temperature showed to be the worst medium, giving the highest TVC in the fillets after thawing. The results supported a slow thawing method (e.g. by cold air) for this fillet product or similar ones, which are processed and frozen pre-rigor mortis.

Storage and initial processing of water samples for organic carbon analysis in runoff

Runoff monitoring experiments are often conducted in remote sites. Sample collection and dispatch for analysis are often delayed due to sites’ remoteness and limited local laboratory facilities. The standard method of dissolved organic carbon (DOC) and total organic carbon (TOC) analysis in water samples requires storage of the samples at 4 °C after collection and analysis with a minimum of delay. However, there is no freezing storage time limit specified to avoid degradation. To overcome the limitations of this approach, we investigated the method of storage, that is refrigeration (4 °C) versus freezing (-18 °C), and the effect of storage time on DOC and TOC fractions in runoff water. Storage of samples at 4 °C for more than a week resulted in a decline of TOC and DOC concentrations in runoff water.•Freezing unfiltered water samples immediately after collection minimized TOC losses during storage, however, it may lead to variable DOC results.•Filtering a subsample of runoff or irrigation water immediately after collection using a 0.45 µm filter and freezing both the filtered and unfiltered samples until analysis of DOC and TOC, respectively, can minimize losses during storage.