Genotypic Variations in Quality and Shelf-Life of Fresh Roots of Philippine Sweet Potato Grown in Two Planting Seasons

Sweet potato breeding in the Philippines has recently integrated root quality and shelf-life attributes in varietal development. In this study, the harvest and post-harvest quality of the fleshy roots of different sweet potato genotypes were determined. These genotypes included the existing recommended varieties and the elite selections from the polycross breeding nursery and were grown during the dry and wet planting seasons. Dry matter, starch, sugar and protein contents of freshly harvested roots were found to differ widely with genotype. During storage at ambient temperatures, starch content decreased, sugar content increased and in some genotypes dry matter increased. Protein content of the stored roots varied only slightly from that of fresh roots. The different genotypes also differed in the degree of weight loss, shrivelling, decay and consequently, shelf-life. Some genotypes had short-lived roots (less than 1 month) while others had roots which were still marketable at the end of the 3-month storage period. Root quality and shelf-life similarly varied with planting season. Some genotypes had increased dry matter, starch and sugar contents and long shelf-life when planted in the dry season while others had these characteristics when produced in the wet months. Protein content generally decreased in wet-season-produced roots. However, a number of genotypes had comparable root quality and shelf-life regardless of planting season.     

低钠盐火腿肠保质期预测及产品致病菌的聚合酶链式反应检测

采用加速破坏性试验模型预测低钠盐火腿肠的保质期,并采用聚合酶链式反应对产品致病菌进行快速检测,同时对贮藏期间火腿肠的质构(嫩度)变化进行分析。结果表明：对照组(3%普通碘盐＋0.3%磷酸盐)、2.5%市售低钠盐＋0.35% TG组、2.0%市售低钠盐＋0.3%磷酸盐组、3%多组分替代盐(NaCl 40%、KCl 35%、CaCl2 15% 和甘氨酸10%)＋0.35% TG组火腿肠在室温(25℃)和低温(4℃)条件下的保质期分别为17.5、17.6、16.9、15.7d和189、208、142、146d;产品在低温(4℃)条件下放置1个月后,各组均无致病菌检出;火腿肠在低温贮藏90d期间,其嫩度变化趋势是先增大后减小。综合比较而言,添加2.5%市售低钠盐+0.35% TG组火腿肠的贮藏稳定性最好。     

大蒜提取物对冷藏蔬菜鱼丸品质的影响

研究蔬菜鱼丸中添加不同量的大蒜提取物(0、100、150、200mg/kg)后在4℃冷藏条件下的品质变化。每5d取鱼丸样品的分析感官特性(感官评分、质构和白度)、微生物(细菌总数)和理化(pH值、TVB-N值和TBA值)等指标。结果表明：添加大蒜提取物的处理组保鲜效果明显优于对照组,其中大蒜提取物添加量在200mg/kg时,保鲜效果最佳,其货架期延长了7～8d。通过处理组与对照组细菌总数、pH值、TBA、TVB-N等品质指标的比较可知,大蒜提取物在鱼丸冷藏保鲜过程中能有效地抑制细菌生长,并减缓蛋白质、脂肪等氧化变质,从而延长了鱼丸的货架期。     

维生素功能饮料在货架期内颜色褐变的研究

研究表明,VC的不稳定和苹果汁中多酚类化合物是引起维生素饮料褐变的主要原因,由于VC分解产生的产物能加速果汁中多酚类化合物的分解和聚合,使得饮料产品颜色在货架期里发生变化,环境温度的升高加速了维生素饮料的褐变。通过添加适当的还原剂保护VC和采用脱色的澄清苹果浓缩汁,降低果汁中的多酚类化合物含量能有效延长轻度褐变的时间,从而延长产品的货架期。     

乳酸链球菌素在烤肉中的应用研究

本文着重论述了乳酸链球菌素在烤肉中的应用.实验证明,乳酸链球菌素能有效地抑制细菌生长繁殖,延长烤肉保质期.     

Effectiveness of Dipping with Phosphate, Lactate and Acetic Acid Solutions on the Quality and Shelf-life of Pork Loin Chop

Extending the shelf‐life of pork loin chops by dipping in 2% acetic acid (AA), 10% sodium lactate (SL), or 10% trisodium phosphate (TSP), compared to the undipped control (CONT), was demonstrated. TSP had the highest pH and water‐holding capacity. However, TSP had a dry and dark visual appearance on the loin chop surface, while AA was similar to pale, soft, and exudative (PSE) pork. CONT and SL had obvious putrid odor with TPC exceeding 10⁷ CFU/g at d 6 and d 9, respectively. Pork loin chops dipped in 10% sodium lactate solution resulted in better visual appearance and lower microbial counts, suggesting a possible extension of the shelf‐life to 6 d under refrigeration.     

冷藏三文鱼片微生物生长动力学模型适用性分析及货架期模型的建立

为研究不同冷藏温度(0,4,10℃)下三文鱼片中菌落总数、明亮发光杆菌、乳酸菌、假单胞菌以及产H2S细菌的生长情况,用不同的微生物生长动力学模型对其微生物生长动态进行非线性拟合,探究动力学模型对冷藏三文鱼片微生物生长的适用性,建立其剩余货架期模型。分别以一级化学反应动力学模型、修正的Gompetz模型、Baranyi and Roberts模型作为一级微生物生长动力学模型,描述微生物在恒定温度下随时间的生长规律;分别以Arrhenius方程和Belehradek方程(平方根模型)为二级模型,描述贮藏温度对微生物生长曲线的最大比生长速率(μmax)及延滞时间(λ)的影响。结果显示:Baranyi and Roberts模型方程能更好地描述冷藏三文鱼片中微生物的生长动态,拟合效果优于一级化学反应动力学模型和修正的Gompertz模型。Baranyi and Roberts模型方程所得参数用Belehradek方程拟合,结果发现冷藏三文鱼片微生物生长的最大比生长速率和延滞时间与贮藏温度呈良好的线性关系。由Belehradek方程建立的冷藏三文鱼片剩余货架期模型相对误差在(±18.90%)内,比Arrhenius方程建立的货架期预测模型预测更准确,可很好地描述菌落总数、假单胞菌、产H2S细菌及明亮发光杆菌随贮藏时间和温度的变化规律,预测冷藏三文鱼片的货架期。     

Retail Shelf-Life of Pork Dipped in Organic Acid before Modified Atmosphere or Vacuum Packaging

Modified atmosphere packaging (MAP) is increasingly popular for meat, but raw, chilled pork in vacuum or anoxic environments has a purple color. The retail shelf‐life of pork chops dipped in 500 ppm ascorbic acid, 250 ppm citric acid, or no acid dip and stored at 1 °C before simulated retail display in MAP with gas exchange or air‐permeable packaging after vacuum pouch storage was determined. The 80% N₂:20% CO₂ in MAP was exchanged with 80% O₂:20% CO₂, and chops were removed from vacuum packages and overwrapped with permeable film (VP‐PVC) on the 7th day before simulated retail display at 4 °C. Shelf‐life traits were determined at 1, 7, 8, 10, 12, and 14 d postpackaging. The pH values changed with time, but returned to post‐dipped, prepackaged levels at the end of simulated retail storage. Weight loss of chops increased (P < 0.05) in VP‐PVC compared with MAP. The a* values increased (P < 0.05) and L* and b* values decreased during simulated retail display, with higher L*, a*, and b* color values for chops in MAP than VP‐PVC. Log numbers of psychrotrophic microorganisms were higher (P < 0.05) on VP‐PVC samples than for chops in MAP on days 12 and 14. Psychrotrophic counts on ascorbic acid‐treated samples were decreased compared with citric acid or no dipping on pork during simulated retail display. Pork chops in MAP with gas exchange had lighter and redder color, increased weight retention, decreased psychrotrophic counts, and increased lipid oxidation compared with conventional vacuum and overwrap packaging systems.     

湿面保鲜工艺研究

湿面属于一种高水分食品(含水量≥60%),它的保藏是生产技术上的关键。面条蒸煮后进行酸洗工艺,可以较好的解决湿面的保鲜问题。本文以面条的酸度、口感和保质期为指标,对酸液槽中酸液的酸度、酸洗时间、酸洗温度三个酸洗工艺参数进行单因素试验和正交试验进行测定和观察,最终得出酸洗的最佳工艺参数。     

复合天然保鲜剂对低温酱鸭保鲜效果的研究

以低温酱鸭为原料，通过对6种天然保鲜剂进行筛选，选出4种抑菌效果较好的，进一步进行组合实验，根据抑菌率得出抑制酱鸭腐败菌的最佳组合为壳聚糖2．00％、乳酸链球菌素（Nisin）0．01％、茶多酚1．00％、桂皮2．40％。采用此最佳组合的复合天然保鲜剂对酱鸭进行保鲜实验，定期测定其微生物指标和理化指标，结果表明利用优选的组合保鲜剂保鲜，加上真空包装、低温水浴杀菌，可使酱鸭保质期冷藏达2-3个月。