CHEMICAL, NUTRITIVE AND SENSORY CHARACTERISTICS OF TOMATOES BEFORE AND AFTER CONVENTIONAL AND MICROWAVE BLANCHING AND DURING FROZEN STORAGE

The objective of this study was to evaluate the effects of microwave blanching on chemical, physical and sensory characteristics of tomatoes prior to and after frozen storage. Tomatoes were blanched (4 min) using four treatments: conventional boiling water (BW), steam (ST), microwaved in a glass container (MW), and microwaved in boilable bags (MWB). The lowest moisture content occurred in MW‐blanched tomatoes before (92%) and after (86%) frozen storage. These tomatoes had the highest reduced ascorbic acid (RAA) content and the highest RAA retention (> 23 mg/100 g, >91%) after blanching and after frozen storage. After blanching, MWB‐blanched tomatoes were the lightest, while after frozen storage, ST‐blanched tomatoes were the lightest. BW‐blanched tomatoes had generally higher flavor, texture and appearance scores. This study demonstrated that though visual color and sensory attributes were highest for BW‐blanched tomatoes, MW‐blanched tomatoes retained more nutritive value in the finished product.     

冻藏时间对速冻水饺品质影响的试验研究

主要考查冷冻保藏时间对于速冻水饺的理化性质、微生物指标及感官性状的影响。结果表明,随保藏时间延长,饺皮的水分含量呈线性规律下降,从最初的（37．25±0．44）％降至试验末期的（32．5±0．92）％。而对于样品的酸价,随保藏时间延长,酸价升高,从初始的（2．01±0．01）mg KOH／g升至试验末期的（2．38±0．02）mgKOH／g。菌落总数及嗜冷菌菌落总数结果相似,都随保藏时间延长而增加,菌落总数从（1．27±0．09）×10^5 cfu／g升至（3．26±0．08）×10^5 cfu／g,而嗜冷菌菌落总数从（2．44±0．06）×10^5 cfu／g升至（3．73±0．15）×10^5 cfu／g。结合对水饺饺皮和饺馅的感官评价表明,速冻水饺的食用品质随保藏时间呈下降趋势,相对来讲,保藏时间越短,样品的食用品质越好。     

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.     

MODELING THE SENSORY QUALITIES OF PROCESSED APPLES AFTER CONTROLLED ATMOSPHERE STORAGE AND FROZEN STORAGE1

Durational effects of controlled atmosphere storage (CA) and frozen storage on apple quality were studied for commercially processed pies made from Northern Spy, Idared and Nova Spy apples. Sensory tests on apple pie quality indicated that the duration of apples in CA significantly affected the quality of the processed apple. Extending the CA duration of the apples to 45 weeks resulted in a pie filling with reduced apple flavor, tartness and astringency, and with increased sweetness and off‐flavor. To minimize flavor/taste changes throughout the processing season, close attention must be given to the product's sugar/acid formulation: by week 27 for Idared apples and by week 33 for Northern Spy and Novaspy apples. The texture and appearance of processed Novaspy and Idared fruits were affected earlier in CA than Northern Spy apples. The frozen product was relatively stable for all three varieties, especially for apples processed early in the storage season (15–27 weeks). A strategy that utilizes short‐ to medium‐term CA with longer‐term frozen storage would optimize quality across the season.     

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.     

SENSORY QUANTIFICATION OF BITTERNESS AND FLAVOUR OF BEER DURING STORAGE*

Sensory techniques were utilized to measure bitterness and degree of liking for commercial lagers, and to quantify aroma and flavour qualities of two sets of experimental lagers. Significant negative correlations were obtained between sensory bitterness and degree of liking for 17 commercial beers, by inexperienced as well as by trained judges. Sensory bitterness was positively correlated with BU values, with both measurements negatively correlated with beer age. In experimental lagers, BU values decreased with increasing time and temperature of storage, but sensory bitterness, as determined by trained judges, decreased only with storage time. Increases in malty, ethanol, and skunky aromas with time of storage were accompanied by decreases in hoppy, musty, and wet cardboard aromas. Baked aroma increased sharply with increasing storage temperature. In a second set of experimental lagers varying in pH (3·7, 4·2, or 4·6) and/or headspace gas, sourness was markedly affected by pH whereas baked flavour was significantly stronger in beers with O₂ than in those with CO₂ headspace. The data are discussed in terms of differences between analytical and consumer-type sensory testing, and in terms of changes in aroma and flavour attributable to iso-α-acid content, pH, headspace gas, and time and temperature of storage.     

EFFECTS OF MODIFIED ATMOSPHERE PACKAGING AND FILM ON SENSORY AND STORAGE PROPERTIES OF FROZEN HAM STRIPS

The effectiveness of modified atmosphere packaging and barrier properties of films upon the product attributes of frozen (IQF) ham strips, that are normally found at salad bars, was studied every 28 days over a period of 196 days. Three gases/mixture were used (CO₂, N₂ and ambient air) for flushing two pouches, one made from normal barrier film (861) and the other from a high barrier film (863). A triangle test and sensory evaluations were performed by a semi-trained panel (six members) for the following traits: freshness, structure, mouth feel, overall evaluation, aroma, appearance and off-flavors. Overall evaluation scores were acceptable up to 140 days of storage, regardless of the pouch used, but from 140 to 196 days, the product would be only marginally acceptable. Ham strips stored in N₂ or CO₂ atmospheres had a higher acceptance level than those stored frozen in ambient air. Panelists distinquished between fresh and stored product more frequently (75%) when the product was stored in ambient air pouches rather than CO₂ or N₂ atmospheres. Pouches made from the higher barrier film had lower (398/g) total aerobic plate counts than pouches (736/g) made from normal barrier film, but these counts are low and would be acceptable in industry.     

PHYSICOCHEMICAL AND SENSORY CHARACTERISTICS OF FLAVORED SOYMILK DURING REFRIGERATION STORAGE1

The goal of this study was to investigate changes in physicochemical, microbiological, and sensory properties of flavored soymilk under refrigeration storage. The soymilk contained 85.7% moisture, 10.5% carbohydrates+ash, 2.2%protein, and 1.6% fat. Sensory analysis showed that chocolate and almond flavorings improved the aroma ofsoymilks (P < 0.05). Addition of gum partially masked the beany flavor and off‐flavor. All the soymilks had less than 10 CFU/mL of total aerobic, coliform, and E. coli counts. After one month's storage, TBARS decreased by about 20% (P < 0.05). All soymilk samples exhibited a pseudoplastic flow, and addition of 0.05% iota‐carrageenan increased their viscosity and shear stress (P < 0.05). Overall, flavored soymilks had improved desirable attributes and reduced undesirable characteristics over plain soymilk, and all were stable for one month at refrigeration condition.     

A RESEARCH NOTE: SENSORY QUALITY CHANGES OF HIGH MOISTURE PINEAPPLE BITS DURING STORAGE

Minimally processed high moisture pineapple bits prepared in sucrose syrups, in order to decrease water activity to 0.92, 0.95 and 0.97, were stored at 30, 35 and 40C and evaluated by selected and trained sensory panelists using the Karlsrühe Quality Test. Color, flavor and texture changes were significantly lower for the 0.92 a_w product stored at 30C. It can be predicted by shelf‐life estimation that this product will maintain a satisfactory sensorial and microbiological quality for up to 50 days.     

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.     

EFFECTS OF DIETARY SOYBEAN LECITHIN ON SOME SENSORY AND RHEOLOGICAL PROPER TIES OF FROZEN AND NON-FROZEN CHICKEN MEAT

Soy bean lecithin was added to practical rations fed to 144 broiler chicks. The dark and white meats from frozen and non-frozen carcasses were submitted to both mechanical (Warner Bratzler and Instron Universal Testing Machine) and sensory assessments of tenderness. A good correlation was observed between the two types of measurements. Regression equations indicated that higher lecithin contents in the rations decreased sensory toughness of the white meat. Freezing of the meats at – 40°C had little effect on texture.     

USE OF NATURAL PLANT EXTRACTS IN BATTER COATING OF SHRIMP AND THEIR EFFECTS ON THE QUALITY OF SHRIMP DURING FROZEN STORAGE

Commercial extracts of garlic, tomato and grape seed were separately added into batter coating formulation. Quality changes of coated shrimps were investigated during frozen storage. Samples with added extracts had higher pH values than the control group. Higher total volatile basic nitrogen value was found in the sample with tomato extract compared with extract containing garlic and grape seed extracts. The lowest trimethylamine concentration was found in the sample containing garlic extract. Although the most effective extract in retarding oxidation was grape seed extract, garlic extract had protective effect against spoilage. The lowest scores for sensory appearance, odor and taste were found in samples with grape seed extract. It was concluded that use of plant extracts in the coating mixture affected the quality of shrimp during frozen storage. It was also found that the sample with garlic extract was the best product in terms of sensory characteristics.

PRACTICAL APPLICATIONS

Shrimp is a perishable product and it is important to extend its shelf life. Battered products have gained a grown consideration in the field of ready to eat seafood. Most of researches on batter-coated food products have focused on reducing the amount of fat absorbed during frying and improving rheological properties. There is no study on addition of antioxidative, antibacterial agents to coating mix. This is a new approach to improve the quality and shelf life.     

EVALUATION OF MICROBIOLOGICAL, PHYSICOCHEMICAL AND SENSORY QUALITIES OF CHITOSAN TOFU DURING STORAGE

Tofu containing both low and high viscosity chitosan was prepared and changes in the microbiological, physicochemical and sensory properties of the tofu during storage were investigated. The colony forming units of mesophilic and psychrotrophic microorganisms in tofu containing high viscosity chitosan were markedly lower during storage than those in the control tofu as well as the tofu containing low viscosity chitosan. The _pH of the tofu samples increased during storage. The L and a values of the tofu, especially the control tofu, increased during storage. In the sensory test, the roasted nutty and beany aromas of the tofu decreased during storage. Instrumental analysis of hardness and chewiness of the tofu decreased during storage. Overall preference for the tofu gradually decreased during storage, but overall preference for the tofu containing high viscosity chitosan scored higher than the other tofu samples.     

ENZYME ACTIVITY AND QUALITY OF FROZEN GREEN BEANS AS AFFECTED BY BLANCHING AND STORAGE

Effects of different blanching conditions on residual enzyme activities and quality changes in green beans during frozen storage were studied. Green beans were blanched at various temperature and time combinations at both pilot plant and commercial scales. After storage at —23°C for 3, 6, 9 and 12 months they were analyzed for residual activities of catalase, lipoxygenase, polyphenoloxidase and peroxidase; changes in sensory quality as evaluated by a taste panel; and color and firmness as measured with instruments. Most of enzymes were inactivated during normal blanching but the residual activities varied among enzymes. Beans blanched above 82°C for 3.5 min yielded higher sensory scores for the quality attributes tested than those blanched at the lower temperatures. However, there appears to be no direct relationship between the quality attributes measured and the residual enzyme activities during 12 months storage.