EFFECTS of SHUCKING METHOD ON OPENING, MEAT YIELD and SELECTED QUALITY PARAMETERS of WEST AFRICAN CLAM, GALATEA PARADOXA (BORN)

Samples (n= 100) of freshly harvested clams ( Galatea paradoxa Born) from the Cross River, Nigeria, were subjected after 24 h depurations to heat treatment (steam and water at 60, 70, 80, 90, 100C) for 1–6 min to evaluate the effects of level of heat treatment on opening, meat yield, sensory properties, proximate composition, pH and electrical conductivity (EC). Observations were also made on the effects of some chemical shucking aids (NaOH, NaHCO₃, Na₂CO₃, NaCl) in 60C water on these parameters.
Results showed that boiling water was most effective in opening the clams, with 100% shucking achieved in 1 min. Steam was least effective, requiring 6 min for 100% opening. Temperature significantly and strongly influenced meat yield (p<0.05;r=-0.92). pH (p<0.01; r=0.97), EC (p<0.05; r =0.65) and sensory properties (p<0.05). In general, shucking aids reduced opening time, significantly p<0.05) raised meat pH and EC, and with the exception of NaCl, insignificantly (P>0.05) improved yield. NaHCO₃, and Na₂CO₃, which cut time for 100% opening from 5 min to 2 min were most effective. There were slight but significant (P <0.05) drops in meat moisture, crude protein and ash contents with increase in temperature (T). the model equations, pH = 4.69 + 0.021 T and % yield = 39.95–0.172 T were found to reliably predict meat pH and yield, with insignificant differences (P>0.05) between predicted and experimental values.     

EVALUATION OF PRODUCTIVITY AND POSTHARVEST QUALITY DURING STORAGE OF FIVE AGARICUS BISPORUS STRAINS

Five Agaricus bisporus commercial strains (S100, A15, F56, F40 and F62) were evaluated as regards their colonization rates, yields, quality characters and storability. Concerning their colonization performance, the mycelial growth rates examined in “race tubes” on sterile compost, as well as earliness in fructification did not differ significantly. Significantly lower was the yield of strain S100 compared to the yield of strains F62 and F56, which presented the greatest cumulative biological efficiency values. However, mushroom number and average weight presented negative relation. For the storage and quality study, mushrooms at the “closed‐cap” stage packaged in 500‐g plastic containers were stored for 5 days at 2C and 5 days at 18C (shelf life). The respiration behavior of the five strains was similar with the mass loss not exceeding 15% during storage at 2C and 40–50% at the end of the shelf life. Also, no differences in the whiteness and texture change were detected and a correlation between the period of pileus diameter increase and the respiration rate was found. According to their color and texture quality assessment, mushrooms deriving from the first four strains may be considered well acceptable at the end of the shelf life, whereas these from strain F62 just saleable.     

QUALITY OF SWEETPOTATO FLOUR DURING PROCESSING AND STORAGE

Sweetpotato flour can easily be promoted as a substitute for wheat flour in sweet baked products and can also be used for its high carotenoid content. However, the price of the sweetpotato flour must be competitive with wheat flour and be of good quality. This article defines and describes the different quality characteristics of sweetpotato flour. After an overview of the different steps and equipment used in the small-scale processing of sweetpotato flour, the influence of the different processing steps and storage on the quality characteristics are reviewed.     

QUALITY OF MEAT PRODUCTS DURING REFRIGERATED AND ULTRA-CHILLED STORAGE

Standard domestic refrigerators store food between 1 and 5C (33.8–41F). A manufacturer recently developed a refrigerator capable of storing food in the “ultra‐chilled region” (?3 to ?7C) and claimed that storage of fresh meat in this region better maintains quality. To understand quality in terms of chemical reaction rates, microbial growth and texture and flavor changes, three common consumer meat products – steak, ground beef patty and salmon – were stored for a selected period of time, as determined by microbial testing, in five refrigerator models with different environmental conditions (constant temperature and temperature fluctuation). At the end of the storage period, consumer panelists assessed the quality of the cooked samples by ranking them according to preference. In addition, instruments were used to measure the color and shear cutting force (for steak only) of each sample. Results from the consumer Ranking R‐Index Test indicate that panelists preferred samples stored under or near ultra‐chilled conditions rather than samples stored under standard refrigerated conditions. The ultra‐chilled samples not only had higher panelist rankings and more favorable comments, but also had lower microbial aerobic plate counts. The instrument readings, however, highly varied and did not correlate well with sensory data.     

CHANGES IN TOTAL PHENOLIC AND FLAVONOID CONTENTS OF ROWANBERRY FRUIT DURING POSTHARVEST STORAGE

ABSTRACT

Postharvest storage conditions of rowanberry (Sorbus aucuparia) fruits were investigated. The influences of temperature and storage time on total phenolic content were observed. Both variables affected phenolic content of rowanberries, and their total phenolic contents significantly reduced during the 20‐day storage at 4 and 22C. The loss of total phenolic was found to be almost 50% of its initial amount (3,619.8 mg/kg fresh weight [fw]) at 22C, which was higher than occurred loss (30%) at 4C. An investigation of rowanberry flavonoids showed the presence of rutin, quercetin‐3‐glucoside and quercetin‐3‐D‐galactoside (Q3DG). Quantitative analysis of berry flavonoids showed Q3DG as a major compound, being 24.55 mg/kg fw. The highest reduction (86% of its initial amount) was also seen in that compound level compared with other ones. Degradation kinetics of flavonoids was studied at 22C over 16 days of storage. Checking of model adequacies indicated that their reductions followed a first‐order kinetic.

PRACTICAL APPLICATIONS

Postharvest storage has been taken, increasing the interest of scientists because of various reasons, one of which is explained next. The presented results indicated the direct and/or indirect influence of storage conditions on the quality of berries, implying that whoever is planning to store plant and/or plant origin food products in a refrigerator or at room temperature should consider the conditions and their possible effects on the quality parameters from the aspects of economics and nutritional properties of products. In the present study, the stability of an important bioactive group, phenolics, in rowanberries and the influences of environmental conditions were examined, and additionally, degradation kinetics of major phenolic group, flavonoids, was analyzed. The results are valuable and helpful for the evaluation of the postharvest storage and its effect on rowanberries. Introduced model may be helpful for the prediction of storage time required for the degradation of phenolics up to the acceptable limit.     

RHEOLOGICAL AND SENSORY QUALITY OF READY-TO-BAKE CHAPATTI DURING FROZEN STORAGE

The effect of prolonged frozen storage at − 18C, on the textural and sensory properties of ready-to-bake frozen chapatti (R-BFC) was evaluated. The R-BFC samples were prepared from normal- (control) and microwave-treated (18% moisture content for 80 s) wheat grains. Results showed that the extensibility of dough and maximum load for resistance increased gradually in both the samples during frozen storage; however, the increase was lesser in the treated ones. Chapattis prepared from both R-BFC samples exhibited higher hardness, cohesiveness, chewiness and lower springiness values during frozen storage. Microwave-treated R-BFC samples were rated as better retained in color, texture and overall acceptability scores as compared with control, up to 6 months of storage at − 18C. Thiamin and riboflavin contents were monitored during frozen storage and a loss of 12.0–14.5% in thiamin and 4–6% in riboflavin after 6 months of frozen storage was recorded.

PRACTICAL APPLICATIONS

During frozen storage, various physical, rheological and sensory changes occur in the food products, which determine the consumer's acceptability. The results of this study will help to establish quality of the frozen chapattis with respect to texture, color and aroma which will meet the consumer's acceptance. The protocol for the storage of frozen chapattis will help the industry to deliver the product of optimum quality.     

QUALITY CHANGES OF SARDINE (SARDINA PILCHARDUS) PATTIES DURING REFRIGERATED STORAGE

In this study, quality changes in sardine patties stored at 4C were investigated. Total viable bacteria, psychrotrophic and coliform bacteria counts of sardine patties increased from 2.50 log cfu/g, 2.60 log cfu/g, 19 MPN/g to 6.15 log cfu/g, 6.45 log cfu/g, 70 MPN/g on day 6, respectively. Yeast–molds, Staphylococcus aureus and Escherichia coli were not detected during the storage period. Total volatile basic nitrogen, thiobarbituric acid and trimethylamine nitrogen values of sardine patties were 13.66 mg/100 g, 1.50 mg MA/kg and 1.20 mg/100 g at the beginning and 29.55 mg/100 g, 3.60 mg MA/kg and 5.01 mg/100 g at the end of the storage period (at day 6), respectively. Based on sensory evaluation, the shelf life of sardine patties was determined to be 4 days during refrigerated storage. When chemical, microbiological and sensory analyses were compared, sensory analysis was the found to be most effective for determining the shelf life of sardine patties .

PRACTICAL APPLICATIONS

There is a possibility of consuming sardines as fish patties when catches are large. Sardines are very suitable for patties because of their flavor and taste, and their consumption is very large as fresh fish in Turkey. In recent years, the increase in civilization or socioeconomic factors such as the increasing numbers of working women have led to direct consumers' preference for ready-to-eat foods. Thus, sardine patties were made and quality changes in sardine patties during refrigerated storage were investigated.     

PINK SALMON (ONCORHYNCHUS GORBUSCHA) QUALITY DURING ICE AND CHILLED SEAWATER STORAGE

Pink salmon were stored up to ten days in ice, chilled seawater (CSW), transferred from ice to CSW and from CSW to ice, and evaluated by chemical, physical, microbiological, and sensory methods. The sensory quality of CSW-held fish declined at a faster rate than for iced fish. CSW-held fish had higher weight gain, higher salt and hypoxanthine levels and had softer texture than iced fish. Microbial counts were highest for iced fish and a two-log increase occurred during storage. Moraxella species were predominant in the microbial flora of iced fish whereas Pseudomonas species were predominant in the microbial flora of CSW-held fish. Ice was superior to CSW for maintaining salmon quality.     

QUALITY CHANGES OF BLUE CRAB (CALLINECTES SAPIDUS) MEAT DURING FROZEN STORAGE

The aim of the investigation was to determine the quality changes of blue crab (Callinectes sapidus) meat during frozen storage. Blue crabs were obtained directly from fishing boats in the Gulf of Antalya, Turkey and immediately transferred to the laboratory alive. Whole crabs were placed into polyethylene polyamide (PE/PA) pouches, shrunk and stored at ?18C for 10 months. The main changes that take place in blue crabmeat were investigated by means of sensory assessments (odor, appearance), chemical analyses (total volatile bases (TVB‐N), trimethylamine (TMA‐N)) and physical measurements (pH). TVB‐N, TMA‐N values and pH were significantly (P < 0.01) different following frozen storage. Moreover, it was observed that the differences in odor values were significant (P < 0.05), while appearance values were not. All of the measurements indicated that blue crabmeat kept its good quality at ?18C for 10 months.     

花粉多糖对酸奶贮藏中酸度及感官品质的影响

以牛乳为原料进行发酵,并添加花粉多糖研制多糖酸奶.测定贮藏期间对酸奶的酸度,色泽、气味、滋味和组织状态等感官指标进行评定,研究多糖对酸奶酸度和感官品质的影响.结果表明.多糖可抑制酸度上升,延迟酸奶的后酸化过程.多糖在酸度上可延长酸奶贮藏期5 d～6 d.     

EFFECT OF HARVESTING SEASON AND POSTHARVEST TREATMENTS ON STORAGE LIFE OF MEXICAN LIMES (Citrus aurantifolia Swingle)

Changes in susceptibility to chilling of citrus fruits vary with the low temperature applied, storage period, growing area, season, time of harvest and postharvest treatments. The objective of this study was to determine the effect of low temperatures on the quality of Mexican limes coated with wax applied through spraying or dipping, and treated with thiabendazole (TBZ) at 500 ppm and gibberellic acid (GA3) at 250 ppm. Weight loss, % of juice, degrees Brix, titratable acidity, color development and severity of chilling injury were examined weekly during storage. The results, obtained from fruit collected in two harvest periods, demonstrated that limes during the maximum production period of harvest in July, in contrast to those harvested in September, retained 90.6% of their fruit marketability. The conditions under which the best quality was obtained were the following: waxing by dipping + TBZ at 500 ppm + GA₃ at 250 ppm and 10C storage temperature with RH at 85–90%.     

STUDIES ON POSTHARVEST PHYSIOLOGY AND THE STORAGE TECHNOLOGY OF MANGO (MANGIFERA INDICA L.)

Mango (Mangifera indica L. cv. Hongxiangya and Wacheng) was chosen to study the effect of postharvest biological characters in different storage conditions. The determining items included respiratory rate, total sugar, vitamin C (Vc) content, firmness, polyphenol oxidase (PPO) and peroxidase (POD). The results showed that both 8 and 11C were the better storage temperatures, and the storage life would last 50 days in this situation. The respiration rate increased quickly between the 16th to the 22nd days; the peak values were the 28th and 25th days at 8C for Hongxiangya and Wacheng, respectively. The flesh firmness decreased dramatically at 6 days after harvest. Total sugar content, Vc content, PPO and POD increased at first and then decreased. The color changed from green to yellow with the increase of carotenoids content. After treatment with thiabendozole and iprodione, the number of rot fruits was markedly lower than the other treatments. The best temperature is 11 and 14C for Hongxiangya and Wacheng, respectively. The rot rate is 6.77 and 8.33% with 1,000‐ppm iprodine treatment after 50‐days storage.